CA1180055A - Multiband tuning system for a television receiver - Google Patents
Multiband tuning system for a television receiverInfo
- Publication number
- CA1180055A CA1180055A CA000408359A CA408359A CA1180055A CA 1180055 A CA1180055 A CA 1180055A CA 000408359 A CA000408359 A CA 000408359A CA 408359 A CA408359 A CA 408359A CA 1180055 A CA1180055 A CA 1180055A
- Authority
- CA
- Canada
- Prior art keywords
- tuning
- band
- frequency
- signal
- signals
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H03J5/00—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner
- H03J5/24—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H03J5/00—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner
- H03J5/24—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection
- H03J5/242—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection used exclusively for band selection
- H03J5/244—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection used exclusively for band selection using electronic means
Landscapes
- Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
- Channel Selection Circuits, Automatic Tuning Circuits (AREA)
- Superheterodyne Receivers (AREA)
- Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)
- Circuits Of Receivers In General (AREA)
- Filters And Equalizers (AREA)
Abstract
RCA 77,024 ABSTRACT
A multiband tuning system produces an IF signal from RF signals residing in, in the order named, a first broadcast band, a first cable band, a second broadcast band and a second cable band. A control device generates a tuning signal having a magnitude determined by the frequency of a selected channel. A first filter selects RF signals corresponding to channels selected in a first tuning band including the first broadcast band and a lower frequency portion of the first cable band in response to the tuning signal. A second filter selects RF signals corresponding to channels selected in a second tuning band including an upper frequency portion of the first cable band, the second broadcast and the second cable bands in response to the tuning signal. A selection device enables operation of the first filter when the selected channel is within the first tuning band and enables operation of the second filter when the selected channel is in the second tuning band.
A multiband tuning system produces an IF signal from RF signals residing in, in the order named, a first broadcast band, a first cable band, a second broadcast band and a second cable band. A control device generates a tuning signal having a magnitude determined by the frequency of a selected channel. A first filter selects RF signals corresponding to channels selected in a first tuning band including the first broadcast band and a lower frequency portion of the first cable band in response to the tuning signal. A second filter selects RF signals corresponding to channels selected in a second tuning band including an upper frequency portion of the first cable band, the second broadcast and the second cable bands in response to the tuning signal. A selection device enables operation of the first filter when the selected channel is within the first tuning band and enables operation of the second filter when the selected channel is in the second tuning band.
Description
3~
TUNING SYSTEM FOR A TELEVISION RECEIVER
6 This in~ention relates to tuning systems for television receivers for selecting one of a plurality of channels disposed in a plurality of frequency bands.
The tuning systems in commercially available television (TV) receivers commonly employ a plurality of tuners, each including its own mixer, for receiving signals in a plurality of TV frequency bands. For example, a first tuner selects channels in the VHF-TV frequenc~ bands (54-88 MegaHertz (MHz) and 174-216 MHz) while a second tuner selects channels in the UHF-TV frequency bands 16 (470-890 MHz). When it is desired for the TV receiver to also accept cable television (CATV) signals, its tuning system may require the addition of a third tuner and mixer.
Double conversion tuning systems to avoid the complexity and expense inherent in a plurality o~ tuners have been disclosed f;or receiving broadcast (off-the-air) VHF-TV and UHF-TV signals such as that described by D. L. Ash, "High Performance TV Receiver", IEEE Transactions on Consumer Electronics, Volume CE-24, No. 1, February 1978, Pages 39-46. The need still exists, however, for a simple 26 and low-cost tuning system for receiving VHF-TV, UHF-TV
and CATV signals.
In the present invention, a multiband tuning system produces an IF signal from RF signals residing in, in the order named, a first broadcast band, a first cable B0 band, a second broadcast band and a second cable band. A
control device generates a tuning signal having a magnikude determined by the frequency of a selected ahannel.
first ~ilter selects RF ~ignals corresponding to channels selected in a ~irst tuning band including the first 86 broadcast band and a lower frequency portion of the first cable band in response to the tuning signal. A second ~ilter seleats RF signals corresponding to channels selected in a second tuning band including an upper frequency portion of the first cable band, the second ~0 broadcast and the second cable bands in response to the tuning signal. A selection device enables operation of the first filter when the selected channel is within the first S ~uning band and enables operation of the second filter when the selected channel is in the second tuning band.
In the drawings:
FIG~RE 1 is a schematic diagram in block diagram form of including an embodiment of the present invention;
FIGURES 2, 3, 5 and 6 are graphical representations of various amplitude versus frequency response charac-teristics associated with the embodiment of FIGURE l; and FIGURES 4, 7 and 8 are schematic dia~rams of circuits useful in the tuning system of FIGURE 1.
In the double conversion tuning system of FIGURE 1, television signals received at UHF antenna input 10, at VHF antenna input 30A and at CATV input 30B are coupled to diplexer 20 as will be described below. That system is a double conversion tuning system because two frequency conversions ~shifts) are performed. In the United States, those television signals comprise the channel numbers and reside in the frequency bands indicated in the ~ollowing table.
T A B L E
Frequency Range Channel TV Band (Me~aHertz)Number Low VHF Broadcast (L-VHF) 54-88 2-6 Midband Cable (P~B-CATV) 90-174- A-5 to I
High VHF Broadcast (H-VHF) 174-216 7-13 Superband Cable ~SB-CATV) 216-402 J to W ~ 17 UHF Broadcast (UHF) 470-890 14-83 Each channel is alloted about 6 M}lz of bandwidth in the 3B ~requency ~pectrum and has a picture carrier at a frequency 1.25 MHz greater than the ~requency at the lower limit Gf itB
assigned channel bandwidth. Where speciflc channel Prequencies are reEerred to in the Eollowing de~criptions, that frequency will correspond to the frequ,ency to which the picture carrier of the selected televis:ion channel is translated in the particular portion of the tuning s~stem being described.
The frequency spectrum for channel frequencies S in the various TV frequency bands in the United States is shown in FIGURE 2(a). For the L-VHF band 202, H-VHF
band 206, and UHF band 210, the amplitude of received signals is shown as a plurality of levels indicating that broadcast signals can vary in strength over a wide range, for example, between 10 microvolts and 100 millivolts.
Received CATV signals, on the other hand, exhibit a much smaller variation in signal strenyth, typically between 1 and 6 millivolts, as illustrated for the MB-CATV band 204 and the SB-CATV band 208.
FIGURE 2(b) defines the low-band, high-band and UHF-band of radio frequencies (RF) associated with filters 44, 36 and 14, respectively~ of FIGURE 1 to be described below. The first intermediate frequency (IF) i5 selected to be at 415.75 MHz, which is between the SB-CATV and the UHF-TV bands. It is also without the radar band of about 4~0-450 MHz and so is unlikely to interfere wi~h, or be~interfered with by, other signal sources. The second IF is at the standard TV IF frequency of 45.75 MHz.
It is understood that while the present invention is described in termsjof the various broadcast and cable bands presently used in the United States, the invention is not limited to that arrangement. For example, broadcast band signals could in fact be supplied via a cable.
When the TV channel selected is within the UHF
band, it i9 coupled ~rom UH~ antenna 10 to diplexer input ~OA via U~F band ~re~uency selective tunable ~ilter 14 of ~'IGUR~ 1~ Filter 14 receives tuning potential VT at connection 14C so that it pre~erentially passes the 36 Erequencies corresponding to the selected TV channel between its input 14A and its output 14B.
FIGURE 3 shows frequency selective attenuation characteristic 300 corresponding to the selection o~ TV
channels at relatively lower UHF frequency ft~ Filter 14 exhibits a generally low-pass characteri~tic characterized by lesser attenuation at lower frequency portion 302 of curve 300 and relatively greater attenuation at higher frequency portion 304. Filter 14 preferentially passes signals at about ~he selected channel frequency ft as indicated by the peak near that frequency of bandwidth 306. Bandwidth is defined between the intersections of characteristics 300 with phantom lines 308 indicating 3 dB greater attenuation than in the passband. Characteristic 300' corresponds to characteristlc 300 when the selected channel frequency ft is at relatively higher frequency f't- For filter 14, bandwidth 306 is a~out 25 M~z when frequency ft corresponds to UHF channel 14, while bandwidth 306' increases somewhat to about 40 MHz when frequency f't corresponds to UHF channel 83, for the circuit described below with respect to FIGURE 4. A specific embodiment of filter 14 is described ~elow.
Trap 12 reduces the level of any 416 MHz signals received by UHF antenna 10 since the 416 M~z first IF
frequency is near the UHF band. Those undesirable signals could either be externally developed or be leaked from the first IF section. This tends to reduce unwanted signals at the first IF frequency from being applied to the IF circuits.
Trap 12 exhibits high-pass frequency characteristic 500 shown in FIGURE 5 in that it exhibits little attenuation in its portion 504 at frequencies greater than fc which corresponds to the lowest frequency in the UHF band (about 470 MHz) and greater attenuation in portion 502 at lower frequencies. Around the IF frequency fi (416 MHz), trap 12 exhibits greatest attenuation as indicated by portion 506 of characteristic 500.
UHF ampli~ier 16 aouples signals between output 14B o~ ~ilter 14 and input 20A o diplexer 20, exhibits 14 15 dB o~ gAin over the UHF frequency range and ha~
8~ input and output impedances of about 50 ohms. Amplifier 16 i8 operative only when a channel in the UHF band has been selected because its opexating voltage, bandswitch voltage VB3 tabout 18 volts), is present only when channels in the UHF ~requency band have been selected, as indicated by level 260 oE FIGURE 2(f).
~ a'~3~
TV signals in the VHF and CATV bands are partitioned into low and high tuning bands as follows.
Those signals span a range of frequencies in excess of seven-to-one; tuning over a range greater than three-to-one is impractical owing ~o the limited range of voltage-variable capacitance diodes. Partitioning that 54-402 MHz range between the MB-CATV and H-VHF bands (at about 174 MHz) would still re~uire a tuning range of about 3 1/4-to-one for the low-band. The present apparatus partitions the tuning bands at a frequency within the MB CATV band at about 150 MHz,as shown in FIGURE 2(b). Thus, each of the high and low tuning bands includes frequencies over a range of less than three-to-one ratio.
; 15 The selection o low and high tuning band frequencies is also influenced ~y design considerations for filters 36 and 44. In filter des~gn, it is more difficult to achieve a given narrow bandwidth at higher frequencies than at lower frequencies; it is also more difficult to obtain constant bandwidth in a filter tunable over a wide ra~ge of frequencies. To minimiæe distortion and adjacent channel interference, a narrower filter bandwidth is necessary where the channel~signal amplitudes vary wi~ely (as ~or VHF-TV broadcast signals) than where there is a lesser amplitude range (as for CATV
signals). Because the boundary between low- and high-~and has been established at 150 MHz within the MB-CATV band, the widely varying h-VHF and H-VHF broadcast TV signals are both at the low frequency ends of the tuning system bands and the more controlled MB-CATV and SB-CATV signals are at the high ends of those bandsO Thus, the frequency paxtitioning o~ the ~ilters employed in the present tuning syYtem desirably provide~ satis~actory performance while ea~ing the di~fiaulty of the design requirements 3~ ~or the tunable filters employed therein.
TV signal~ in the VHF and CATV ~requency bands are coupled to di.plexer 20 as Eollows~ In FIGURE 1, switch Sl~ can be switched to posi~ion BC-~ to apply signals ~rom VHF antenna 30A to input 32A of trap 32 or can be connected to position CA-A to apply CATV siqnals from input terminal 30B thereto. Trap 32 is similar to trap 12 described above with respect to FIGURE 5 except that its maximum attenuation range 502 is at the second IF frequency fi ~about 46 MHz) which is near frequency fc (about 54 MHz) corresponding to the lowest frequency to be received (VHF channel 2)~ Trap 32 couples signals in both the low (54 to 150 MHz) and high (150 to 402 MHz) bands to node 32Bo If the selected channel is in the high-band, then VB2 is applied to render switches 34 and 38 conductive (closed) to thereby couple high-band filter 36 between nodes 32B and 40A. If the selected channel is in the low-band, however, then VBl is applied to switches 42 and 46 which are then r~endered conductive to connect lS low-band filter 44 between nodes 32B and 40A.
High-band tunable filter 36 exhibits the high-pass frequency selective characteristic 600 shown in FIGURE 6 in that greater attenuation occurs in relatively lower frequency portion 602 than in relatively higher frequency portion 604~ As a result, filter 36 not only selects frequencies corresponding to the selected channel ft but also tends to reject signals at lower frequencies, parii-cularly those in the low tuning band range of frequencies.
Bandwidth is indicated for curve 600 with respect to _3 dB line 608. As higher frequency channels are selected, the bandwidth of filter 36 increases. Characteristic 600' corresponds to characteristic 600 when selected channel frequency ft is at relatively higher frequency ft'. When filter 36 is tuned so that ft corresponds to MB-CATV
channel F, bandwidth 606 is about 18 MHz; when f't corresponds to SB-CATV channel W ~ 17, bandwidth 606' is about 40 MHz.
Low-band ~unable filter 44 exhibits low-pass ~re~uency ~elective characteristic 300 shown in FIGURE 3 3~ and described above in relation ~o UHF filter 14 e~cept that its bandwidth i9 allowed to increa~e to a substantially greater degree as higher frequency channels are selected.
Bandwidth 306 is about 8 MHx when ft corresponds to VHF
channel 2, and bandwidth 306' is about 20 M}lz when f't corresponds to MB-CATV channel E. Filter 44 thus not V5~
only selects frequencies corresponding to the selected channel ft but also tends to reject signals at higher frequencies, particularly those in the high tuning band and at the first IF frequency.
S VHF amplifier 40 in FIGURE 1 couples signals from node 40A to input 20B of diplexer 20 and is sub-stantially the same as UHF amplifier 16 described above.
It di~fers, however, in that its operating potential VB12 is applied via a diode "OR" circuit comprising diodes D12 an D14 so that amplif.ier 40 receives as operating potential bandswitch voltage VB1 or VB2 whenever a channel within the low or high tuning bands is selected, but does not receive operating po~ential when a channel in the UHF band is selected. Node 40 can thus be disconnected from diplexer input 20B when a UHF channel is selected.
Diplexer 20 of FIGURE 1 receives RF signals from the UHF band signal path, at its input connection 20A, receives RF signals from the VHF and CATV band signal paths at its input 20B, and combines those signal paths to pass RF signals to its output connection 20C. Within diplexer 20, the circuit path comprises high-pass filter 22 coupling input 20A to a circuit point 24 followed by low-pass filter 26 coupling that circuit point to output 20C. Input 20B is connected to circuit point 24 by a plurality of low-pass filters 28 connected in cascade.
Mixer 50 receives RF signals from diplexer output 20C and local oscillator requency signals from amplifier 52 via point 52A. In response, mixer 50 translates RF signal at the selected channel fre~uency to A s.ignal at the ~lrst IF of about 416 MHæ (i.e., the first ~re~uency conversion). U. S. Patent No. 4,397,037, entitled, ~ , describes suitable implementati.ons of diplexer 20 and mixer 50.
Amplifier 52 provides a relatively higher level frequency slgnal in a range of 10-18 dBm to ~requency mixer 50 and maintains an impedance of about 50 ohms at point 52A. When mixer 50 is driven by such higher level S of frequency signal, RF signal from diplexer 20 can also be of greater relative strength without introducing additional distortion.
It is preferred to select a relatively high IF frequency of about 416 MHz, a high drive level to mixer 50, for the reasons described above. It is also preferred to minimize the distortion in mixer 50 by selecting the gain of the circuits between antennas 10 and 30A and mixer 50 to be just sufficient to obtain an acceptable noise figure in the receiver. In that case, the respective 16 bandwidths of filters 14, 36 and 44 can be relatively greater for the double conversion tuning system as compared to the narrower bandwidths which would be required in a single conversion tuning system, to obtain equivalent distortion-and noise performance. That advantage permits filter bandwidth to be allowed to increase along with the frequency of the selected channel, as described above.
Thi~ first IF signal is then amplified by IF
amplifier 60. Amplifier 60 can include a two-section 26 input filter tuned to the 416 MHz ~F fraquency with about 12 MHz bandwidth, and a three-section output filter also tuned to the 416 MHz IF frequency with about 10 MHz bandwidth. The amplified,IF signal at IF amplifier output 62A is then frequency mixed with a 370 MHz frequency signal '30 from local oscillator 64 by frequency mixer 62 in a second fre~uency conversion to produce the conventional IF signal at 46 MHz. ~he ~econd IF signal is then coupled to IF
output 68 via IF filter 66.
'runing control 70 re~ponds to a channel ~6 selection to.dev~lop tuning poten~ial VT and bandswitch potentials VBl, VB2 and VB3. Tuning potential V~, shown in FIGURE 2(c), typically varies between a low level of about 1.5 volts, indicated by phantom line 220, and a h.igher level of about 24 volts, indicated by phantom line 222.
~ When the selected channel is in the low tuning band, _ 9 _ VT tends toward a low value at point 224 when VHF channel
TUNING SYSTEM FOR A TELEVISION RECEIVER
6 This in~ention relates to tuning systems for television receivers for selecting one of a plurality of channels disposed in a plurality of frequency bands.
The tuning systems in commercially available television (TV) receivers commonly employ a plurality of tuners, each including its own mixer, for receiving signals in a plurality of TV frequency bands. For example, a first tuner selects channels in the VHF-TV frequenc~ bands (54-88 MegaHertz (MHz) and 174-216 MHz) while a second tuner selects channels in the UHF-TV frequency bands 16 (470-890 MHz). When it is desired for the TV receiver to also accept cable television (CATV) signals, its tuning system may require the addition of a third tuner and mixer.
Double conversion tuning systems to avoid the complexity and expense inherent in a plurality o~ tuners have been disclosed f;or receiving broadcast (off-the-air) VHF-TV and UHF-TV signals such as that described by D. L. Ash, "High Performance TV Receiver", IEEE Transactions on Consumer Electronics, Volume CE-24, No. 1, February 1978, Pages 39-46. The need still exists, however, for a simple 26 and low-cost tuning system for receiving VHF-TV, UHF-TV
and CATV signals.
In the present invention, a multiband tuning system produces an IF signal from RF signals residing in, in the order named, a first broadcast band, a first cable B0 band, a second broadcast band and a second cable band. A
control device generates a tuning signal having a magnikude determined by the frequency of a selected ahannel.
first ~ilter selects RF ~ignals corresponding to channels selected in a ~irst tuning band including the first 86 broadcast band and a lower frequency portion of the first cable band in response to the tuning signal. A second ~ilter seleats RF signals corresponding to channels selected in a second tuning band including an upper frequency portion of the first cable band, the second ~0 broadcast and the second cable bands in response to the tuning signal. A selection device enables operation of the first filter when the selected channel is within the first S ~uning band and enables operation of the second filter when the selected channel is in the second tuning band.
In the drawings:
FIG~RE 1 is a schematic diagram in block diagram form of including an embodiment of the present invention;
FIGURES 2, 3, 5 and 6 are graphical representations of various amplitude versus frequency response charac-teristics associated with the embodiment of FIGURE l; and FIGURES 4, 7 and 8 are schematic dia~rams of circuits useful in the tuning system of FIGURE 1.
In the double conversion tuning system of FIGURE 1, television signals received at UHF antenna input 10, at VHF antenna input 30A and at CATV input 30B are coupled to diplexer 20 as will be described below. That system is a double conversion tuning system because two frequency conversions ~shifts) are performed. In the United States, those television signals comprise the channel numbers and reside in the frequency bands indicated in the ~ollowing table.
T A B L E
Frequency Range Channel TV Band (Me~aHertz)Number Low VHF Broadcast (L-VHF) 54-88 2-6 Midband Cable (P~B-CATV) 90-174- A-5 to I
High VHF Broadcast (H-VHF) 174-216 7-13 Superband Cable ~SB-CATV) 216-402 J to W ~ 17 UHF Broadcast (UHF) 470-890 14-83 Each channel is alloted about 6 M}lz of bandwidth in the 3B ~requency ~pectrum and has a picture carrier at a frequency 1.25 MHz greater than the ~requency at the lower limit Gf itB
assigned channel bandwidth. Where speciflc channel Prequencies are reEerred to in the Eollowing de~criptions, that frequency will correspond to the frequ,ency to which the picture carrier of the selected televis:ion channel is translated in the particular portion of the tuning s~stem being described.
The frequency spectrum for channel frequencies S in the various TV frequency bands in the United States is shown in FIGURE 2(a). For the L-VHF band 202, H-VHF
band 206, and UHF band 210, the amplitude of received signals is shown as a plurality of levels indicating that broadcast signals can vary in strength over a wide range, for example, between 10 microvolts and 100 millivolts.
Received CATV signals, on the other hand, exhibit a much smaller variation in signal strenyth, typically between 1 and 6 millivolts, as illustrated for the MB-CATV band 204 and the SB-CATV band 208.
FIGURE 2(b) defines the low-band, high-band and UHF-band of radio frequencies (RF) associated with filters 44, 36 and 14, respectively~ of FIGURE 1 to be described below. The first intermediate frequency (IF) i5 selected to be at 415.75 MHz, which is between the SB-CATV and the UHF-TV bands. It is also without the radar band of about 4~0-450 MHz and so is unlikely to interfere wi~h, or be~interfered with by, other signal sources. The second IF is at the standard TV IF frequency of 45.75 MHz.
It is understood that while the present invention is described in termsjof the various broadcast and cable bands presently used in the United States, the invention is not limited to that arrangement. For example, broadcast band signals could in fact be supplied via a cable.
When the TV channel selected is within the UHF
band, it i9 coupled ~rom UH~ antenna 10 to diplexer input ~OA via U~F band ~re~uency selective tunable ~ilter 14 of ~'IGUR~ 1~ Filter 14 receives tuning potential VT at connection 14C so that it pre~erentially passes the 36 Erequencies corresponding to the selected TV channel between its input 14A and its output 14B.
FIGURE 3 shows frequency selective attenuation characteristic 300 corresponding to the selection o~ TV
channels at relatively lower UHF frequency ft~ Filter 14 exhibits a generally low-pass characteri~tic characterized by lesser attenuation at lower frequency portion 302 of curve 300 and relatively greater attenuation at higher frequency portion 304. Filter 14 preferentially passes signals at about ~he selected channel frequency ft as indicated by the peak near that frequency of bandwidth 306. Bandwidth is defined between the intersections of characteristics 300 with phantom lines 308 indicating 3 dB greater attenuation than in the passband. Characteristic 300' corresponds to characteristlc 300 when the selected channel frequency ft is at relatively higher frequency f't- For filter 14, bandwidth 306 is a~out 25 M~z when frequency ft corresponds to UHF channel 14, while bandwidth 306' increases somewhat to about 40 MHz when frequency f't corresponds to UHF channel 83, for the circuit described below with respect to FIGURE 4. A specific embodiment of filter 14 is described ~elow.
Trap 12 reduces the level of any 416 MHz signals received by UHF antenna 10 since the 416 M~z first IF
frequency is near the UHF band. Those undesirable signals could either be externally developed or be leaked from the first IF section. This tends to reduce unwanted signals at the first IF frequency from being applied to the IF circuits.
Trap 12 exhibits high-pass frequency characteristic 500 shown in FIGURE 5 in that it exhibits little attenuation in its portion 504 at frequencies greater than fc which corresponds to the lowest frequency in the UHF band (about 470 MHz) and greater attenuation in portion 502 at lower frequencies. Around the IF frequency fi (416 MHz), trap 12 exhibits greatest attenuation as indicated by portion 506 of characteristic 500.
UHF ampli~ier 16 aouples signals between output 14B o~ ~ilter 14 and input 20A o diplexer 20, exhibits 14 15 dB o~ gAin over the UHF frequency range and ha~
8~ input and output impedances of about 50 ohms. Amplifier 16 i8 operative only when a channel in the UHF band has been selected because its opexating voltage, bandswitch voltage VB3 tabout 18 volts), is present only when channels in the UHF ~requency band have been selected, as indicated by level 260 oE FIGURE 2(f).
~ a'~3~
TV signals in the VHF and CATV bands are partitioned into low and high tuning bands as follows.
Those signals span a range of frequencies in excess of seven-to-one; tuning over a range greater than three-to-one is impractical owing ~o the limited range of voltage-variable capacitance diodes. Partitioning that 54-402 MHz range between the MB-CATV and H-VHF bands (at about 174 MHz) would still re~uire a tuning range of about 3 1/4-to-one for the low-band. The present apparatus partitions the tuning bands at a frequency within the MB CATV band at about 150 MHz,as shown in FIGURE 2(b). Thus, each of the high and low tuning bands includes frequencies over a range of less than three-to-one ratio.
; 15 The selection o low and high tuning band frequencies is also influenced ~y design considerations for filters 36 and 44. In filter des~gn, it is more difficult to achieve a given narrow bandwidth at higher frequencies than at lower frequencies; it is also more difficult to obtain constant bandwidth in a filter tunable over a wide ra~ge of frequencies. To minimiæe distortion and adjacent channel interference, a narrower filter bandwidth is necessary where the channel~signal amplitudes vary wi~ely (as ~or VHF-TV broadcast signals) than where there is a lesser amplitude range (as for CATV
signals). Because the boundary between low- and high-~and has been established at 150 MHz within the MB-CATV band, the widely varying h-VHF and H-VHF broadcast TV signals are both at the low frequency ends of the tuning system bands and the more controlled MB-CATV and SB-CATV signals are at the high ends of those bandsO Thus, the frequency paxtitioning o~ the ~ilters employed in the present tuning syYtem desirably provide~ satis~actory performance while ea~ing the di~fiaulty of the design requirements 3~ ~or the tunable filters employed therein.
TV signal~ in the VHF and CATV ~requency bands are coupled to di.plexer 20 as Eollows~ In FIGURE 1, switch Sl~ can be switched to posi~ion BC-~ to apply signals ~rom VHF antenna 30A to input 32A of trap 32 or can be connected to position CA-A to apply CATV siqnals from input terminal 30B thereto. Trap 32 is similar to trap 12 described above with respect to FIGURE 5 except that its maximum attenuation range 502 is at the second IF frequency fi ~about 46 MHz) which is near frequency fc (about 54 MHz) corresponding to the lowest frequency to be received (VHF channel 2)~ Trap 32 couples signals in both the low (54 to 150 MHz) and high (150 to 402 MHz) bands to node 32Bo If the selected channel is in the high-band, then VB2 is applied to render switches 34 and 38 conductive (closed) to thereby couple high-band filter 36 between nodes 32B and 40A. If the selected channel is in the low-band, however, then VBl is applied to switches 42 and 46 which are then r~endered conductive to connect lS low-band filter 44 between nodes 32B and 40A.
High-band tunable filter 36 exhibits the high-pass frequency selective characteristic 600 shown in FIGURE 6 in that greater attenuation occurs in relatively lower frequency portion 602 than in relatively higher frequency portion 604~ As a result, filter 36 not only selects frequencies corresponding to the selected channel ft but also tends to reject signals at lower frequencies, parii-cularly those in the low tuning band range of frequencies.
Bandwidth is indicated for curve 600 with respect to _3 dB line 608. As higher frequency channels are selected, the bandwidth of filter 36 increases. Characteristic 600' corresponds to characteristic 600 when selected channel frequency ft is at relatively higher frequency ft'. When filter 36 is tuned so that ft corresponds to MB-CATV
channel F, bandwidth 606 is about 18 MHz; when f't corresponds to SB-CATV channel W ~ 17, bandwidth 606' is about 40 MHz.
Low-band ~unable filter 44 exhibits low-pass ~re~uency ~elective characteristic 300 shown in FIGURE 3 3~ and described above in relation ~o UHF filter 14 e~cept that its bandwidth i9 allowed to increa~e to a substantially greater degree as higher frequency channels are selected.
Bandwidth 306 is about 8 MHx when ft corresponds to VHF
channel 2, and bandwidth 306' is about 20 M}lz when f't corresponds to MB-CATV channel E. Filter 44 thus not V5~
only selects frequencies corresponding to the selected channel ft but also tends to reject signals at higher frequencies, particularly those in the high tuning band and at the first IF frequency.
S VHF amplifier 40 in FIGURE 1 couples signals from node 40A to input 20B of diplexer 20 and is sub-stantially the same as UHF amplifier 16 described above.
It di~fers, however, in that its operating potential VB12 is applied via a diode "OR" circuit comprising diodes D12 an D14 so that amplif.ier 40 receives as operating potential bandswitch voltage VB1 or VB2 whenever a channel within the low or high tuning bands is selected, but does not receive operating po~ential when a channel in the UHF band is selected. Node 40 can thus be disconnected from diplexer input 20B when a UHF channel is selected.
Diplexer 20 of FIGURE 1 receives RF signals from the UHF band signal path, at its input connection 20A, receives RF signals from the VHF and CATV band signal paths at its input 20B, and combines those signal paths to pass RF signals to its output connection 20C. Within diplexer 20, the circuit path comprises high-pass filter 22 coupling input 20A to a circuit point 24 followed by low-pass filter 26 coupling that circuit point to output 20C. Input 20B is connected to circuit point 24 by a plurality of low-pass filters 28 connected in cascade.
Mixer 50 receives RF signals from diplexer output 20C and local oscillator requency signals from amplifier 52 via point 52A. In response, mixer 50 translates RF signal at the selected channel fre~uency to A s.ignal at the ~lrst IF of about 416 MHæ (i.e., the first ~re~uency conversion). U. S. Patent No. 4,397,037, entitled, ~ , describes suitable implementati.ons of diplexer 20 and mixer 50.
Amplifier 52 provides a relatively higher level frequency slgnal in a range of 10-18 dBm to ~requency mixer 50 and maintains an impedance of about 50 ohms at point 52A. When mixer 50 is driven by such higher level S of frequency signal, RF signal from diplexer 20 can also be of greater relative strength without introducing additional distortion.
It is preferred to select a relatively high IF frequency of about 416 MHz, a high drive level to mixer 50, for the reasons described above. It is also preferred to minimize the distortion in mixer 50 by selecting the gain of the circuits between antennas 10 and 30A and mixer 50 to be just sufficient to obtain an acceptable noise figure in the receiver. In that case, the respective 16 bandwidths of filters 14, 36 and 44 can be relatively greater for the double conversion tuning system as compared to the narrower bandwidths which would be required in a single conversion tuning system, to obtain equivalent distortion-and noise performance. That advantage permits filter bandwidth to be allowed to increase along with the frequency of the selected channel, as described above.
Thi~ first IF signal is then amplified by IF
amplifier 60. Amplifier 60 can include a two-section 26 input filter tuned to the 416 MHz ~F fraquency with about 12 MHz bandwidth, and a three-section output filter also tuned to the 416 MHz IF frequency with about 10 MHz bandwidth. The amplified,IF signal at IF amplifier output 62A is then frequency mixed with a 370 MHz frequency signal '30 from local oscillator 64 by frequency mixer 62 in a second fre~uency conversion to produce the conventional IF signal at 46 MHz. ~he ~econd IF signal is then coupled to IF
output 68 via IF filter 66.
'runing control 70 re~ponds to a channel ~6 selection to.dev~lop tuning poten~ial VT and bandswitch potentials VBl, VB2 and VB3. Tuning potential V~, shown in FIGURE 2(c), typically varies between a low level of about 1.5 volts, indicated by phantom line 220, and a h.igher level of about 24 volts, indicated by phantom line 222.
~ When the selected channel is in the low tuning band, _ 9 _ VT tends toward a low value at point 224 when VHF channel
2 is selected and tends towara a high value at point 226 when MB-CATV channel E is selected. When the selected channel is in the high tuning band, VT also tends toward a low value at point 228 when MB-CATV channel F is selected and tends toward a high valu~ at point 230 when SB-CATV
channel W + 17 is selected. Similarly, VT tends toward a low value at point 232 when UHF channel 14 is selected and toward a high value at point 234 when UHF channel 83 is selected. Bandswitch signals VBl, VB2 and VB3 are at a high level of about 18 volts as indicated by characteris-tics 240, 250 and 260 of FIGURES 2(d), 2(e) and 2(f) only when a channel in the band to which they correspond has been selected, and are at zero volts when a channel outside that particular band is selected.
` . ~ .
;
Three tunable voltage controlled local oscillators (VCO) 54, 56 and 58 are provided to develop the local oscillator frequency signals in the three tuning bands. That is done so that the frequency of a particular oscillator (54, 56, 58) can be conveniently made to track the frequency tuning of its associated filter (14, 36, 44, respectively), responsive to the same tuning potential VT.
The range of frequencies at which frequency signals must be supplied to amplifier 52 at point 52B can be seen from the ollowin~ table.
--~L~
Local Oscillator 5 B _ Channel Number Frequenc~ (MegaHertz) Low Band 2tL-VHF) 471 (VCO 58) 6(~-VHF) 499.
A-5 (MB-CATV) 507 E(MB-CATV) 561 10 High Band F(MB-CATV) 557 (VCO 56) I(MB-CATV) 585 7 (H-VHF) 591 13(L-VHF) 627 J(SB-CATV) 633 16 W + 17(SB-CATV) 813 UHF Band 14 (UHF) 887 (VCO 54) 83(UHF) 1301 ..
Oscillators 54, 56 and 58 respectively receive bandswitch potentials VBl, VB2 and VB3 as their operating potential, so to be operative only when the channel selected falls within the frequency band with which the particular oscillator is associated.
Suitable implementations for filters 14, 36 and 2~ 44, shown in FIGURES 4 and 7,will now be described.
UHF-band filter 14, shown in FIGURE 4, is a double-tuned, low-pass ilter with "high-side inductive coupling" provided between its input 14A and its output 14B by the serial connection of inductors L402, L406, L408, L410 and L414. C408 serves as a DC blocking capacitor with negligible AC impedance at UHF frequencies. Inductors L404 and L406 serve as a tapped inductor configuration Eor maintai.ning the impedance at input 14~ at about 50 ohms.
Simlla~ly, inductor~ L410 and ~412 ~erve a~ a tapp~d
channel W + 17 is selected. Similarly, VT tends toward a low value at point 232 when UHF channel 14 is selected and toward a high value at point 234 when UHF channel 83 is selected. Bandswitch signals VBl, VB2 and VB3 are at a high level of about 18 volts as indicated by characteris-tics 240, 250 and 260 of FIGURES 2(d), 2(e) and 2(f) only when a channel in the band to which they correspond has been selected, and are at zero volts when a channel outside that particular band is selected.
` . ~ .
;
Three tunable voltage controlled local oscillators (VCO) 54, 56 and 58 are provided to develop the local oscillator frequency signals in the three tuning bands. That is done so that the frequency of a particular oscillator (54, 56, 58) can be conveniently made to track the frequency tuning of its associated filter (14, 36, 44, respectively), responsive to the same tuning potential VT.
The range of frequencies at which frequency signals must be supplied to amplifier 52 at point 52B can be seen from the ollowin~ table.
--~L~
Local Oscillator 5 B _ Channel Number Frequenc~ (MegaHertz) Low Band 2tL-VHF) 471 (VCO 58) 6(~-VHF) 499.
A-5 (MB-CATV) 507 E(MB-CATV) 561 10 High Band F(MB-CATV) 557 (VCO 56) I(MB-CATV) 585 7 (H-VHF) 591 13(L-VHF) 627 J(SB-CATV) 633 16 W + 17(SB-CATV) 813 UHF Band 14 (UHF) 887 (VCO 54) 83(UHF) 1301 ..
Oscillators 54, 56 and 58 respectively receive bandswitch potentials VBl, VB2 and VB3 as their operating potential, so to be operative only when the channel selected falls within the frequency band with which the particular oscillator is associated.
Suitable implementations for filters 14, 36 and 2~ 44, shown in FIGURES 4 and 7,will now be described.
UHF-band filter 14, shown in FIGURE 4, is a double-tuned, low-pass ilter with "high-side inductive coupling" provided between its input 14A and its output 14B by the serial connection of inductors L402, L406, L408, L410 and L414. C408 serves as a DC blocking capacitor with negligible AC impedance at UHF frequencies. Inductors L404 and L406 serve as a tapped inductor configuration Eor maintai.ning the impedance at input 14~ at about 50 ohms.
Simlla~ly, inductor~ L410 and ~412 ~erve a~ a tapp~d
3~ Lndu~tor con~igura~ion ~or maintaining th~ :Lmp~dance a~
outpu~ 14~ at about 50 ohms. Inpu~ and output inductors ~402 and ~414 ai~ in maintaining a sub~antially con~tant bandwidth over the broad tuning rang~ o iLter ~4.
Capacitor C404 is connected in parallel with inductor L408 to resonate at about 1,000 MHz. Variable fre~uency , ~ :
' ~ .
tuning is provided by variable capacitance diodes CD42 and CD44, respectively connected from the ends of the L408-C404 tuned circuit to ground via coupling capacitors C402 and C406 which exhibit a very low impedance at the frequencies of television signals passed by filter 14. Tuning potential VT at terminal 14C is applied to vary the capacitance of diodes CD42 and CD44 via isolation resistors R402 and R404, respectively. VT can vary between about ~0 1.5 and 24 volts for UHF channels 14-83.
FIGURE 7 is a detailed diagram of switches 34, 38, 42 and 44 and of tunable filters 36 and 44. Switch 34 conducts TV signals from node 32B to input 36A via DC
blocking capacitors C702 and C704 when PIN diode SD72 is rendered conductive by the application of bandswitch voltage VB2 through RF choke L702. Resistor R702 controls the forward current flowing through SD72 when a channel in the high-band is selected. During that time, PIN diode SD74 is held reverse-biased by the potential across resistor R702. When the channel selected is in a band other than the high-band, diode SD74 is forward-biased by either VBl applied through diode D84 or by VB3 applied through diode D78. The forward current flowing in SD74 is determined by resistorl R702, and the potential thereacross applies 2S reverse-bias to SD72. Resistor R704 provides a return path when SD74 is reverse-biased. Capacitor C706 is a DC blocking capacitor providing a low impedance connection at TV frequencies between the cathode of SD72 and ground when SD74 is conductive.
Switch 38 is of the same type as is switch 34 !
and ~he~ are rendered conductive and nonconductive together. Switches 42 and ~6 are also o~ lik~ sor~ to that of ~witch 34, however, they are rendered conductive only when the ~elected channel is in the low-band. Corresponding ~6 elements, which perform similar ~functions in switches 34, 38, 42 and 46, are li.sted on the ~ame line oE the following table.
. ~
~ .
40 ~
p~
.: .
5 Switch 34 Switch 38 Switch 42 Switch 46 C702 C714 C72~ C734 C70g C712 C722 C732 High-band tuna~le filter 36 exhibits a high~pass - characteristic owing to the series connection ofi capacitances C708, C710 and capacitance diodes CD72 and ao CD74 between input 36A and output 36B and the "low-side"
inductive coup~ing of shunt inductances ~706, Lj708 and L710. The section including capacitors. C708, C710 and L708 exhibits a high-pass characteristic tuned to reject signals in the low-band. Variable tuning is pr~vided 2~ by varying the respective capacitances of variable capacitance diodes CD72 and CD74 responsive to reverse-bias applied respectively via resistors R706 and R708 from tuning potential VT at terminal 36C. The capacitance of CD72 resonates with inductors L704 and L706, while that o~ CD74 re~onates with L710 and L712.
Low-band ~unable Eilter 44 is "high-side inductively coupled" and is simllar to UHF ~ilter 14 describ~d above. Inductor ~726 and capacltor C728 Are tuned to resonate at about 200 MHz, thereby to block ~G signals in the high-band. That ~requency is ~urther tuned to lower values by the appliaa~ion oE tuning potential VT
~rom terminal 44C to voltage variable capacitance diodes CD76 and CD78 via resistors R724 and R726. Capaci~ors C726 and C730 provide relatively low impedance paths at TV
frequenaies between the respective cathodes of CD76 and .
'. ' '' - ' ' . ', ' ~ ' .
CD78 and ground. Inductors L722 and L724 serve as a tapped inductance configuration as do inductors L730 and L728.
Modifications to the present invention are contemplated,and the present invention should be limited only by the claims following. For example, switch Sl has been shown as a mechanical switch, because it is presumed that a ~elevision receiver would normally b used with either a VHF antenna 30A or with a CATV connection 30B but not both because VHF channel programming is usually provided by the CATV source as well. However, if full automatic reception were desired, SlA could be replaced with a relay or a PIN diode switch controlled by a bandswitch voltage or by a diplexer.
Furthermore, UHF amplifier 16 and VHF amplifier 40 could be removed,and PIN diode switches of similar sort to switch 34 put in their places if a single amplifier is inserted in connection 20C between diplexer 20 and mixer 50.
A specific modification, desirable when the first IF frequency is about 416 MHz, is shown in FIGURE 8. Broadcast TV signals for VHF channel 12 have a picture carrier at about 205 MHz and a sound carrier at about 210 MHz. Because the second harmonics o~ those 26 carriers, as well as signals at the sum of their frequencies, are close to the IF fre~uency, it is desirable to provide attenuation of those carriers. To that end, L706, described above in relation to FIGURE 7, is selectively coupled to form a trap except at times when channel 12, or adjacent channels 11 and 13, are selected.
Inductance I,806 is located ~o that its coil mutuall~ couples with the two turns o~ the co.tl o~ L706 n~arest to ground G~ ~s a result, capaci~ance C801 i9 re~lected by the trans~ormer coupling between L806 and ~706 to he efEectively in series with the portion o~ L706 ~urthest ~rom ground G. The comblnation serves as a series trap circuit and is tuned to channel 12 providing about 20 dB attenuation at 210 MH2 and about 10 dB at 205 MHz.
A portion oE operating voltage ~V developed by the voltage divider including resistances R801 and R802 is applied to the anode of switch diode SD801. Bypass capacitance C802 couples the upper interconnection of C801 and L806 to ground at TV frequencies at which it exhibits a negligibly 5 small impedance; capacitance C803 similarly couples the cathode of SD801 to ground.
For broadcast reception, switch SlB, which i9 a second pole of switch SlA described above in relation to FIGURE 1, ls in position BC-B to apply voltage ~V to the lO cathode of SD801 via switch S2 and resistance R803 to reverse bias SD801~ Wit~ SD801 reverse biased, C801 is coupled as described abo~e. When any of channels 11, 12 or I3 is selected, S2 transfers from position IN to position IN to forward bias SD801 by groundiny its cathode.
15 As a result, C801 is coupled to ground through the negligibly small impedances of SD801, C803 and C802 essentially short circuiting C801 and thereby disabling the C801-L706 trap circuit just described.
For CATV reception, SlB is transferred to 20 position CA-B to similarly disable the C801-L706-trap circuit.
outpu~ 14~ at about 50 ohms. Inpu~ and output inductors ~402 and ~414 ai~ in maintaining a sub~antially con~tant bandwidth over the broad tuning rang~ o iLter ~4.
Capacitor C404 is connected in parallel with inductor L408 to resonate at about 1,000 MHz. Variable fre~uency , ~ :
' ~ .
tuning is provided by variable capacitance diodes CD42 and CD44, respectively connected from the ends of the L408-C404 tuned circuit to ground via coupling capacitors C402 and C406 which exhibit a very low impedance at the frequencies of television signals passed by filter 14. Tuning potential VT at terminal 14C is applied to vary the capacitance of diodes CD42 and CD44 via isolation resistors R402 and R404, respectively. VT can vary between about ~0 1.5 and 24 volts for UHF channels 14-83.
FIGURE 7 is a detailed diagram of switches 34, 38, 42 and 44 and of tunable filters 36 and 44. Switch 34 conducts TV signals from node 32B to input 36A via DC
blocking capacitors C702 and C704 when PIN diode SD72 is rendered conductive by the application of bandswitch voltage VB2 through RF choke L702. Resistor R702 controls the forward current flowing through SD72 when a channel in the high-band is selected. During that time, PIN diode SD74 is held reverse-biased by the potential across resistor R702. When the channel selected is in a band other than the high-band, diode SD74 is forward-biased by either VBl applied through diode D84 or by VB3 applied through diode D78. The forward current flowing in SD74 is determined by resistorl R702, and the potential thereacross applies 2S reverse-bias to SD72. Resistor R704 provides a return path when SD74 is reverse-biased. Capacitor C706 is a DC blocking capacitor providing a low impedance connection at TV frequencies between the cathode of SD72 and ground when SD74 is conductive.
Switch 38 is of the same type as is switch 34 !
and ~he~ are rendered conductive and nonconductive together. Switches 42 and ~6 are also o~ lik~ sor~ to that of ~witch 34, however, they are rendered conductive only when the ~elected channel is in the low-band. Corresponding ~6 elements, which perform similar ~functions in switches 34, 38, 42 and 46, are li.sted on the ~ame line oE the following table.
. ~
~ .
40 ~
p~
.: .
5 Switch 34 Switch 38 Switch 42 Switch 46 C702 C714 C72~ C734 C70g C712 C722 C732 High-band tuna~le filter 36 exhibits a high~pass - characteristic owing to the series connection ofi capacitances C708, C710 and capacitance diodes CD72 and ao CD74 between input 36A and output 36B and the "low-side"
inductive coup~ing of shunt inductances ~706, Lj708 and L710. The section including capacitors. C708, C710 and L708 exhibits a high-pass characteristic tuned to reject signals in the low-band. Variable tuning is pr~vided 2~ by varying the respective capacitances of variable capacitance diodes CD72 and CD74 responsive to reverse-bias applied respectively via resistors R706 and R708 from tuning potential VT at terminal 36C. The capacitance of CD72 resonates with inductors L704 and L706, while that o~ CD74 re~onates with L710 and L712.
Low-band ~unable Eilter 44 is "high-side inductively coupled" and is simllar to UHF ~ilter 14 describ~d above. Inductor ~726 and capacltor C728 Are tuned to resonate at about 200 MHz, thereby to block ~G signals in the high-band. That ~requency is ~urther tuned to lower values by the appliaa~ion oE tuning potential VT
~rom terminal 44C to voltage variable capacitance diodes CD76 and CD78 via resistors R724 and R726. Capaci~ors C726 and C730 provide relatively low impedance paths at TV
frequenaies between the respective cathodes of CD76 and .
'. ' '' - ' ' . ', ' ~ ' .
CD78 and ground. Inductors L722 and L724 serve as a tapped inductance configuration as do inductors L730 and L728.
Modifications to the present invention are contemplated,and the present invention should be limited only by the claims following. For example, switch Sl has been shown as a mechanical switch, because it is presumed that a ~elevision receiver would normally b used with either a VHF antenna 30A or with a CATV connection 30B but not both because VHF channel programming is usually provided by the CATV source as well. However, if full automatic reception were desired, SlA could be replaced with a relay or a PIN diode switch controlled by a bandswitch voltage or by a diplexer.
Furthermore, UHF amplifier 16 and VHF amplifier 40 could be removed,and PIN diode switches of similar sort to switch 34 put in their places if a single amplifier is inserted in connection 20C between diplexer 20 and mixer 50.
A specific modification, desirable when the first IF frequency is about 416 MHz, is shown in FIGURE 8. Broadcast TV signals for VHF channel 12 have a picture carrier at about 205 MHz and a sound carrier at about 210 MHz. Because the second harmonics o~ those 26 carriers, as well as signals at the sum of their frequencies, are close to the IF fre~uency, it is desirable to provide attenuation of those carriers. To that end, L706, described above in relation to FIGURE 7, is selectively coupled to form a trap except at times when channel 12, or adjacent channels 11 and 13, are selected.
Inductance I,806 is located ~o that its coil mutuall~ couples with the two turns o~ the co.tl o~ L706 n~arest to ground G~ ~s a result, capaci~ance C801 i9 re~lected by the trans~ormer coupling between L806 and ~706 to he efEectively in series with the portion o~ L706 ~urthest ~rom ground G. The comblnation serves as a series trap circuit and is tuned to channel 12 providing about 20 dB attenuation at 210 MH2 and about 10 dB at 205 MHz.
A portion oE operating voltage ~V developed by the voltage divider including resistances R801 and R802 is applied to the anode of switch diode SD801. Bypass capacitance C802 couples the upper interconnection of C801 and L806 to ground at TV frequencies at which it exhibits a negligibly 5 small impedance; capacitance C803 similarly couples the cathode of SD801 to ground.
For broadcast reception, switch SlB, which i9 a second pole of switch SlA described above in relation to FIGURE 1, ls in position BC-B to apply voltage ~V to the lO cathode of SD801 via switch S2 and resistance R803 to reverse bias SD801~ Wit~ SD801 reverse biased, C801 is coupled as described abo~e. When any of channels 11, 12 or I3 is selected, S2 transfers from position IN to position IN to forward bias SD801 by groundiny its cathode.
15 As a result, C801 is coupled to ground through the negligibly small impedances of SD801, C803 and C802 essentially short circuiting C801 and thereby disabling the C801-L706 trap circuit just described.
For CATV reception, SlB is transferred to 20 position CA-B to similarly disable the C801-L706-trap circuit.
Claims (18)
1. A multiband tuning system for producing an IF signal from RF signals residing in, in the order named, a first broadcast band, a first cable band, a second broadcast band, a second cable band, and a third broadcast band comprising:
control means for generating a tuning signal having a magnitude determined by the frequency of a selected channel;
first filter means for selecting RF signals corresponding to channels selected in a first tuning band including said first broadcast band and a lower frequency portion of a said first cable band in response to said tuning signal;
second filter means for selecting RF signals corresponding to channels selected in a second tuning band including a higher frequency portion of said first cable band, said second broadcast band and at least the lower frequency portion of said second cable band in response to said tuning signal;
filter selection means for enabling the operation of said first filter means when the selected channel is in said first tuning band and for enabling the operation of said second filter means when the selected channel is in said second tuning band wherein said filter selection means includes:
an input node at which the signals in said first and second tuning bands are received and an output node, first and second diode means respectively connecting respective input connections of said first and second filter means to said input node, third and forth diode. means respectively connecting respective output connections of said first and second filter means to said output node, and second control means for rendering said first and third diode means conductive when said selected channel is within said first tuning band and for rendering said second and fourth diode means conductive when said selected channel is within said second tuning band;
third filter means for selecting RF signals corresponding to channels selected in a third tuning band including said third broadcast band;
combining means for combining RF signals selected by the enabled one of said first and second filter means and RF signals selected by said third filter means;
local oscillator means for generating a local oscillator signal, the frequency of which is responsive to said tuning signal; and mixing means for translating the frequency of the combined RF signal from said combining means in response to said local oscillator signal to produce said IF signal.
control means for generating a tuning signal having a magnitude determined by the frequency of a selected channel;
first filter means for selecting RF signals corresponding to channels selected in a first tuning band including said first broadcast band and a lower frequency portion of a said first cable band in response to said tuning signal;
second filter means for selecting RF signals corresponding to channels selected in a second tuning band including a higher frequency portion of said first cable band, said second broadcast band and at least the lower frequency portion of said second cable band in response to said tuning signal;
filter selection means for enabling the operation of said first filter means when the selected channel is in said first tuning band and for enabling the operation of said second filter means when the selected channel is in said second tuning band wherein said filter selection means includes:
an input node at which the signals in said first and second tuning bands are received and an output node, first and second diode means respectively connecting respective input connections of said first and second filter means to said input node, third and forth diode. means respectively connecting respective output connections of said first and second filter means to said output node, and second control means for rendering said first and third diode means conductive when said selected channel is within said first tuning band and for rendering said second and fourth diode means conductive when said selected channel is within said second tuning band;
third filter means for selecting RF signals corresponding to channels selected in a third tuning band including said third broadcast band;
combining means for combining RF signals selected by the enabled one of said first and second filter means and RF signals selected by said third filter means;
local oscillator means for generating a local oscillator signal, the frequency of which is responsive to said tuning signal; and mixing means for translating the frequency of the combined RF signal from said combining means in response to said local oscillator signal to produce said IF signal.
2. The tuning system of claim 1 wherein said first tuning band includes RF signals at frequencies less than a predetermined partition frequency selected to be in the range between about 90 and 174 megaHertz, and wherein said second tuning band includes RF signals at frequencies greater than said partition frequency.
3. The tuning system of claim 2 wherein said partition frequency is selected to be about 150 megaHertz.
4. The tuning system of claim 1 wherein said control means maintains said first, second, third and fourth diode means nonconductive when said selected channel frequency is without said first and second tuning bands,
5. The tuning system of claim 1 including:
amplifying means interposed between said output node and said combining means, said amplifying means having an input connection to which said output node connects and having an output connection connected to said combining means, and means for applying an operating potential to said amplifying means when any of said first, second, third and fourth diode means are rendered conductive and for removing said operating potential when said first, second, third and fourth diode means are nonconductive.
amplifying means interposed between said output node and said combining means, said amplifying means having an input connection to which said output node connects and having an output connection connected to said combining means, and means for applying an operating potential to said amplifying means when any of said first, second, third and fourth diode means are rendered conductive and for removing said operating potential when said first, second, third and fourth diode means are nonconductive.
6. The tuning system of claim 1 including:
amplifying means having an input connection to which said third filter means connects and having an output connection connected to said combining means; and means for applying an operating potential to said amplifying means when said selected channel frequency is within said third tuning band and for removing said operating potential when said selected channel frequency is without said third tuning band.
amplifying means having an input connection to which said third filter means connects and having an output connection connected to said combining means; and means for applying an operating potential to said amplifying means when said selected channel frequency is within said third tuning band and for removing said operating potential when said selected channel frequency is without said third tuning band.
7. The tuning system of claim 1 wherein said first filter means includes a double-tuned low-pass filter tunable by a first voltage-variable capacitance diode across which said tuning signal is applied, said low-pass filter being characterized in that it preferentially selects RF signals over a bandwidth including the frequency of the selected channel, which bandwidth is substantially greater when a relatively higher channel frequency is selected than when a relatively lower channel frequency is selected.
8. The tuning system of claim 1 wherein said second filter means includes a double-tuned high-pass filter tunable by a second voltage-variable capacitance diode across which said tuning signal is applied, said high-pass filter being characterized in that it preferentially selects RF signals over a bandwidth including the frequency of the selected channel, which bandwidth is substantially greater when a relatively higher channel frequency is selected than when a relatively lower channel frequency is selected.
9. The tuning system of claim 1 wherein said local oscillator means includes a plurality of tunable oscillators in like number to the number of said filter means, each of said tunable oscillators being tunable responsive to said tuning signal for making the frequency of the local oscillator signal track the frequency of the selected channel tuned by said filter means with which it is associated.
10. The tuning system of claim 1 further comprising:
second local oscillator means for generating a second local oscillator signal at a predetermined frequency;
second mixing means for translating the frequency of said IF signal in response to said second local oscillator signal to develop a second IF signal at a second IF frequency less than that of said IF signal.
second local oscillator means for generating a second local oscillator signal at a predetermined frequency;
second mixing means for translating the frequency of said IF signal in response to said second local oscillator signal to develop a second IF signal at a second IF frequency less than that of said IF signal.
11. The tuning system of claim 10 wherein said first, second and third tuning bands include only RF
signals at frequencies greater than that of said second IF frequency.
signals at frequencies greater than that of said second IF frequency.
12. The tuning system of claim 11 wherein said second IF frequency is about 46 megaHertz.
13. The tuning system of claim 1 wherein said third tuning band includes only RF signals at frequencies greater than about 470 megaHertz, said first and second tuning bands include only RF signal frequencies lesser than about 402 megaHertz, and said IF signal is at an IF
frequency selected to be between about 402 and 470 megaHertz.
frequency selected to be between about 402 and 470 megaHertz.
14. The tuning system of claim 13 wherein said IF frequency is about 416 megaHertz.
15. A multiband tuning system for producing an IF signal from RF signals residing in, in the order named, a first broadcast band, a first cable band, a second broadcast band, and a second cable band, comprising:
control means for generating a tuning signal having a magnitude determined by the frequency of a selected channel;
first filter means responsive to said tuning signal for selecting RF signals corresponding to channels selected in a first tuning band including said first broadcast band and a lower frequency portion of a said first cable band, wherein said first filter means exhibits a peaked response tunable over said first tuning band by a first voltage-variable capacitance device across which said tuning signal is applied, said peaked response to preferentially select ones of said RF signals over a relatively narrow bandwidth including the frequency of the selected channel, which bandwidth is substantially greater when a relatively higher channel frequency in said first tuning band is selected than when a relatively lower channel frequency therein is selected;
second filter means responsive to said tuning signal for selecting RF signals corresponding to channels selected in a second tuning band including a higher frequency portion of said first cable band, said second broadcast band and at least a lower frequency portion of said second cable band, wherein said second filter means exhibits a peaked response tunable over said second tuning band by a second voltage-variable capacitance device across which said tuning signal is applied, said peaked response to preferentially select ones of said RF
signals over a relatively narrow bandwidth including the frequency of the selected channel, which bandwidth is substantially greater when a relatively higher channel frequency in said second tuning band is selected than when a relatively lower channel frequency therein is selected;
filter selection means for enabling the operation of said first filter means when the selected channel is in said first tuning band and for enabling the operation of said second filter means when the selected channel is in said second tuning band; and frequency translating means to which said first and second filter means are coupled for producing said IF
signal from said RF signals corresponding to said selected channel.
control means for generating a tuning signal having a magnitude determined by the frequency of a selected channel;
first filter means responsive to said tuning signal for selecting RF signals corresponding to channels selected in a first tuning band including said first broadcast band and a lower frequency portion of a said first cable band, wherein said first filter means exhibits a peaked response tunable over said first tuning band by a first voltage-variable capacitance device across which said tuning signal is applied, said peaked response to preferentially select ones of said RF signals over a relatively narrow bandwidth including the frequency of the selected channel, which bandwidth is substantially greater when a relatively higher channel frequency in said first tuning band is selected than when a relatively lower channel frequency therein is selected;
second filter means responsive to said tuning signal for selecting RF signals corresponding to channels selected in a second tuning band including a higher frequency portion of said first cable band, said second broadcast band and at least a lower frequency portion of said second cable band, wherein said second filter means exhibits a peaked response tunable over said second tuning band by a second voltage-variable capacitance device across which said tuning signal is applied, said peaked response to preferentially select ones of said RF
signals over a relatively narrow bandwidth including the frequency of the selected channel, which bandwidth is substantially greater when a relatively higher channel frequency in said second tuning band is selected than when a relatively lower channel frequency therein is selected;
filter selection means for enabling the operation of said first filter means when the selected channel is in said first tuning band and for enabling the operation of said second filter means when the selected channel is in said second tuning band; and frequency translating means to which said first and second filter means are coupled for producing said IF
signal from said RF signals corresponding to said selected channel.
16. The tuning system of claim 15 wherein said second filter means includes a resonant trap circuit for attenuating signals at frequencies at about an integral submultiple of that of said IF signal, and means for disabling said trap circuit when said selected channel is at a frequency near said integral submultiple of that of said IF signal.
17. The tuning system of claim 15 wherein said first tuning band includes RF signals at frequencies less than a predetermined partition frequency selected to be in said first cable band is the range between about 90 and 174 megaHertz, and wherein said second tuning band includes RF signals at frequencies greater than said partition frequency.
18. The tuning system of claim 17 wherein said partition frequency is selected to be about 150 megaHertz.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US294,133 | 1981-08-19 | ||
| US06/294,133 US4408348A (en) | 1981-08-19 | 1981-08-19 | Multiband tuning system for a television receiver |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1180055A true CA1180055A (en) | 1984-12-27 |
Family
ID=23132028
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000408359A Expired CA1180055A (en) | 1981-08-19 | 1982-07-29 | Multiband tuning system for a television receiver |
Country Status (21)
| Country | Link |
|---|---|
| US (1) | US4408348A (en) |
| JP (1) | JPS5875316A (en) |
| KR (1) | KR900002956B1 (en) |
| AU (1) | AU558003B2 (en) |
| BE (1) | BE894135A (en) |
| CA (1) | CA1180055A (en) |
| DD (1) | DD202359A5 (en) |
| DE (1) | DE3230738C2 (en) |
| DK (1) | DK371282A (en) |
| ES (1) | ES8305986A1 (en) |
| FI (1) | FI822816L (en) |
| FR (1) | FR2511821B1 (en) |
| GB (1) | GB2105539B (en) |
| IT (1) | IT1159086B (en) |
| NL (1) | NL8203245A (en) |
| NZ (1) | NZ201635A (en) |
| PL (1) | PL136371B1 (en) |
| PT (1) | PT75360B (en) |
| SE (1) | SE8204674L (en) |
| SU (1) | SU1362409A3 (en) |
| ZA (1) | ZA826004B (en) |
Families Citing this family (52)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI75962C (en) * | 1982-03-30 | 1988-08-08 | Rca Corp | AVSTAEMNINGSSYSTEM FOER EN FLERBANDIG TELEVISIONSMOTTAGARE. |
| DE3212731A1 (en) * | 1982-04-06 | 1983-10-06 | Philips Patentverwaltung | TWO-CIRCUIT RESONANCE BAND FILTER FOR CHANNEL SELECTORS |
| CA1210132A (en) * | 1982-09-16 | 1986-08-19 | Tadao Kubodera | Television receiver |
| US4476583A (en) * | 1983-02-28 | 1984-10-09 | Rca Corporation | Electronic tracking for tuners |
| US4481673A (en) * | 1983-03-28 | 1984-11-06 | Rca Corporation | RF Prom tracking for tuners |
| US4575761A (en) * | 1983-04-28 | 1986-03-11 | Rca Corporation | AFT arrangement for a double conversion tuner |
| US4499602A (en) * | 1983-06-28 | 1985-02-12 | Rca Corporation | Double conversion tuner for broadcast and cable television channels |
| US4581643A (en) * | 1983-07-25 | 1986-04-08 | Rca Corporation | Double conversion television tuner with frequency response control provisions |
| DE3333712A1 (en) * | 1983-09-17 | 1985-04-04 | Standard Elektrik Lorenz Ag, 7000 Stuttgart | Mixer arrangement for mixing electrical radio-frequency oscillations |
| JPS6077580A (en) * | 1983-10-05 | 1985-05-02 | Matsushita Electric Ind Co Ltd | Television tuner |
| US4555809A (en) * | 1983-10-26 | 1985-11-26 | Rca Corporation | R.F. Diplexing and multiplexing means |
| US4590613A (en) * | 1983-12-23 | 1986-05-20 | Rca Corporation | Bipolar AGC with RF transistor DC bias point stabilization |
| US4598425A (en) * | 1984-02-09 | 1986-07-01 | Zenith Electronics Corporation | All-channel television tuning system |
| US4642691A (en) * | 1985-02-28 | 1987-02-10 | Rca Corporation | Television signal input filter |
| DE3509517A1 (en) * | 1985-03-16 | 1986-09-25 | Philips Patentverwaltung Gmbh, 2000 Hamburg | CIRCUIT ARRANGEMENT FOR A TUNER FOR SWITCHING TWO FREQUENCY BANDS |
| JPH0614501Y2 (en) * | 1985-04-26 | 1994-04-13 | シャープ株式会社 | Band-pass filter in converter for CATV |
| DE3538921A1 (en) * | 1985-11-02 | 1987-05-14 | Telefunken Electronic Gmbh | Television tuner |
| US4843358A (en) * | 1987-05-19 | 1989-06-27 | General Electric Company | Electrically positionable short-circuits |
| FR2622054B1 (en) * | 1987-10-16 | 1990-04-13 | Const Electro Sa Et | SWITCHABLE TUNING CAVITY FOR BANDPASS FILTER, IN PARTICULAR FOR DUPLEXER, AND TRANSCEIVER FOR RADIOTELEPHONY COMPRISING SUCH A CAVITY |
| KR910003234B1 (en) * | 1988-05-18 | 1991-05-24 | 삼성전자 주식회사 | Low noise block converter for satellite communications |
| DE3821715A1 (en) * | 1988-06-28 | 1990-01-04 | Telefunken Electronic Gmbh | INPUT CIRCUIT OF A TELEVISION TUNER |
| DE3821716A1 (en) * | 1988-06-28 | 1990-01-04 | Telefunken Electronic Gmbh | TELEVISION TUNER WITH A BAND FILTER CIRCUIT |
| KR900004119A (en) * | 1988-08-09 | 1990-03-27 | 안시환 | LNB for simultaneous reception of C / ku-band satellite broadcasting |
| US5020092A (en) * | 1989-06-23 | 1991-05-28 | Motorola, Inc. | Dual-bandwidth cellular telephone |
| US4972455A (en) * | 1989-06-23 | 1990-11-20 | Motorola, Inc. | Dual-bandwidth cellular telephone |
| KR930007300B1 (en) * | 1989-11-29 | 1993-08-04 | 삼성전기 주식회사 | Automatic tuning method of double conversion tuner |
| US5287556A (en) * | 1990-09-28 | 1994-02-15 | Motorola, Inc. | Interference reduction using an adaptive receiver filter, signal strength, and BER sensing |
| US5355520A (en) * | 1990-11-30 | 1994-10-11 | Motorola, Inc. | In-building microwave communication system permits frequency refuse with external point-to-point microwave systems |
| US5379456A (en) * | 1991-02-05 | 1995-01-03 | Whistler Corporation | Multiplying saw phase shift envelope detector |
| US5146227A (en) * | 1991-05-03 | 1992-09-08 | Whistler Corporation | Sweeping receiver |
| GB2266206B (en) * | 1992-04-03 | 1996-01-17 | Prod Art Co Ltd | Pager |
| US5329370A (en) * | 1993-07-13 | 1994-07-12 | Yazolino Lauren F | Remote control system and method for cable television system |
| US6035185A (en) * | 1995-08-17 | 2000-03-07 | Zenith Electronics Corporation | Selective RF circuit with varactor tuned bandpass switched bandpass filters |
| JPH09270602A (en) * | 1996-04-01 | 1997-10-14 | Matsushita Electric Ind Co Ltd | Receiver |
| JP3250785B2 (en) * | 1996-08-09 | 2002-01-28 | アルプス電気株式会社 | TV tuner |
| DE19705612A1 (en) * | 1997-02-14 | 1998-08-20 | Alsthom Cge Alcatel | Tuner for multi frequency signal reception |
| JP3599951B2 (en) * | 1997-05-12 | 2004-12-08 | アルプス電気株式会社 | Television tuner |
| JP2001502876A (en) * | 1997-07-25 | 2001-02-27 | コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ | Multi-standard reception |
| US6504946B1 (en) * | 1998-10-26 | 2003-01-07 | Ncr Corporation | Method of processing misoriented items in an image-based item processing system and an apparatus therefor |
| DE19857303A1 (en) | 1998-12-14 | 2000-06-15 | Thomson Brandt Gmbh | Method for driving a receiving stage |
| DE19932563A1 (en) * | 1999-07-13 | 2001-01-18 | Philips Corp Intellectual Pty | Tuners with at least a first and a second frequency band |
| KR100353861B1 (en) | 1999-11-11 | 2002-09-26 | 한국전자통신연구원 | DTV Tuner Apparatus And Method For Broadband Auto Frequency Channel Selection Using Approximated Frequency Mapping Function |
| GB0122227D0 (en) * | 2001-09-13 | 2001-11-07 | Koninl Philips Electronics Nv | Active tunable filter circuit |
| US7801476B2 (en) * | 2003-09-05 | 2010-09-21 | Gateway, Inc. | Software signal receiver |
| US20060276149A1 (en) * | 2005-06-03 | 2006-12-07 | Microtune (Texas), L.P. | Multi-band broadcast tuner |
| US8494470B2 (en) | 2008-11-25 | 2013-07-23 | Silicon Laboratories Inc. | Integrated receivers and integrated circuit having integrated inductors |
| US8320857B2 (en) | 2009-04-15 | 2012-11-27 | Broadcom Corporation | Method and system for loop through for multi-band TV tuners and set-top box and/or TV set applications |
| US8983417B2 (en) | 2012-01-03 | 2015-03-17 | Silicon Laboratories Inc. | Low-cost receiver using integrated inductors |
| US8725103B2 (en) | 2012-01-03 | 2014-05-13 | Silicon Laboratories Inc. | Receiver including a tracking filter |
| DE102014102518B4 (en) | 2014-02-26 | 2022-04-28 | Snaptrack, Inc. | Package for a tunable filter |
| KR20190107829A (en) | 2018-03-13 | 2019-09-23 | (주)레봇 | Golf swing correcting apparatus |
| KR102591446B1 (en) * | 2021-11-25 | 2023-10-19 | 충남대학교산학협력단 | Dedrift movement A device that corrects posture |
Family Cites Families (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3931578A (en) * | 1973-12-26 | 1976-01-06 | General Electric Company | Multiple frequency band receiver tuner system using single, non-bandswitched local oscillator |
| US3961264A (en) * | 1974-05-02 | 1976-06-01 | Hekimian Laboratories, Inc. | Linear frequency converter with gain independent of circuit parameters |
| US3976943A (en) * | 1974-08-19 | 1976-08-24 | Texas Instruments Incorporated | Phase lock loop AM/FM receiver |
| US3942122A (en) * | 1974-10-15 | 1976-03-02 | Quasar Electronics Corporation | Multiband tuner control system |
| US4002986A (en) * | 1975-03-27 | 1977-01-11 | Zenith Radio Corporation | Television receiver with tuner capable of receiving air and CATV signals |
| JPS5823978B2 (en) * | 1975-11-11 | 1983-05-18 | ソニー株式会社 | Chuyuna |
| FR2371821A1 (en) * | 1976-10-25 | 1978-06-16 | Indesit | TUNING DEVICE FOR TELEVISION RECEIVER |
| US4247953A (en) * | 1977-07-01 | 1981-01-27 | Hitachi, Ltd. | Tunable high-frequency input circuit |
| US4162452A (en) * | 1977-07-05 | 1979-07-24 | Texas Instruments Incorporated | Channel selection for a television receiver having low-gain high frequency RF-IF section |
| GB2000926B (en) * | 1977-07-05 | 1982-04-28 | Texas Instruments Inc | Channel selector for television receiver |
| US4189678A (en) * | 1977-08-18 | 1980-02-19 | Sanyo Electric Co., Ltd. | Combination VHF-UHF tuner for use in a television receiver |
| US4160213A (en) * | 1977-09-29 | 1979-07-03 | Rca Corporation | Mixer injection voltage compensation circuit |
| JPS55121740A (en) * | 1979-03-14 | 1980-09-19 | Alps Electric Co Ltd | Television voice receiving tuner |
| JPS55123229A (en) * | 1979-03-16 | 1980-09-22 | Hitachi Ltd | Tuner for television receiver |
| US4271529A (en) * | 1980-03-20 | 1981-06-02 | Zenith Radio Corporation | Tunable resonant circuits for a multi-band VHF/UHF/CATV tuner |
| US4368540A (en) * | 1981-06-05 | 1983-01-11 | Rca Corporation | Phase locked loop tuning system including a prescaler conditioned to oscillate at an out-of-band frequency |
-
1981
- 1981-08-19 US US06/294,133 patent/US4408348A/en not_active Expired - Lifetime
-
1982
- 1982-07-29 CA CA000408359A patent/CA1180055A/en not_active Expired
- 1982-08-02 PT PT75360A patent/PT75360B/en not_active IP Right Cessation
- 1982-08-12 ES ES514951A patent/ES8305986A1/en not_active Expired
- 1982-08-12 AU AU87121/82A patent/AU558003B2/en not_active Ceased
- 1982-08-12 FI FI822816A patent/FI822816L/en not_active Application Discontinuation
- 1982-08-12 SE SE8204674A patent/SE8204674L/en not_active Application Discontinuation
- 1982-08-17 BE BE0/208832A patent/BE894135A/en not_active IP Right Cessation
- 1982-08-17 GB GB08223587A patent/GB2105539B/en not_active Expired
- 1982-08-18 SU SU823476200A patent/SU1362409A3/en active
- 1982-08-18 DE DE3230738A patent/DE3230738C2/en not_active Expired - Lifetime
- 1982-08-18 IT IT22889/82A patent/IT1159086B/en active
- 1982-08-18 DD DD82242601A patent/DD202359A5/en unknown
- 1982-08-18 NL NL8203245A patent/NL8203245A/en not_active Application Discontinuation
- 1982-08-18 KR KR8203713A patent/KR900002956B1/en not_active IP Right Cessation
- 1982-08-18 ZA ZA826004A patent/ZA826004B/en unknown
- 1982-08-18 DK DK371282A patent/DK371282A/en not_active Application Discontinuation
- 1982-08-18 FR FR8214298A patent/FR2511821B1/en not_active Expired
- 1982-08-18 JP JP57143969A patent/JPS5875316A/en active Granted
- 1982-08-18 NZ NZ201635A patent/NZ201635A/en unknown
- 1982-08-19 PL PL1982237963A patent/PL136371B1/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| NZ201635A (en) | 1985-11-08 |
| PL237963A1 (en) | 1983-02-28 |
| DE3230738A1 (en) | 1983-03-03 |
| FI822816L (en) | 1983-02-20 |
| SE8204674D0 (en) | 1982-08-12 |
| PT75360A (en) | 1982-09-01 |
| IT8222889A0 (en) | 1982-08-18 |
| JPH0322729B2 (en) | 1991-03-27 |
| ES514951A0 (en) | 1983-04-16 |
| ZA826004B (en) | 1983-07-27 |
| SU1362409A3 (en) | 1987-12-23 |
| US4408348A (en) | 1983-10-04 |
| KR900002956B1 (en) | 1990-05-03 |
| PT75360B (en) | 1984-10-31 |
| FR2511821A1 (en) | 1983-02-25 |
| NL8203245A (en) | 1983-03-16 |
| JPS5875316A (en) | 1983-05-07 |
| PL136371B1 (en) | 1986-02-28 |
| ES8305986A1 (en) | 1983-04-16 |
| FR2511821B1 (en) | 1986-11-21 |
| DE3230738C2 (en) | 1998-01-22 |
| AU8712182A (en) | 1983-02-24 |
| SE8204674L (en) | 1983-02-20 |
| GB2105539A (en) | 1983-03-23 |
| AU558003B2 (en) | 1987-01-15 |
| DD202359A5 (en) | 1983-09-07 |
| IT1159086B (en) | 1987-02-25 |
| FI822816A0 (en) | 1982-08-12 |
| BE894135A (en) | 1982-12-16 |
| KR840001418A (en) | 1984-04-30 |
| DK371282A (en) | 1983-02-20 |
| GB2105539B (en) | 1985-01-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1180055A (en) | Multiband tuning system for a television receiver | |
| US4397037A (en) | Diplexer for television tuning systems | |
| US4418427A (en) | Tuning system for a multi-band television receiver | |
| US4555809A (en) | R.F. Diplexing and multiplexing means | |
| US4905306A (en) | Filter switching arrangement for a tuner | |
| US4731877A (en) | Tunable lowpass-highpass switching filter | |
| US6351294B1 (en) | Television signal receiving tuner capable of receiving FM broadcasting signals without being affected by other interference signals | |
| CA1193032A (en) | Tuning system for a multi-band television receiver | |
| US4584544A (en) | Bandswitched interstage coupling network including a high side coupled capacitor | |
| US5054117A (en) | Tunable UHF filter for switchable VHF/UHF receiver | |
| JP3481115B2 (en) | Receiving machine | |
| US4442548A (en) | Television receiver tuning circuit tunable over a wide frequency range | |
| US4363135A (en) | Four band VHF varactor tuner | |
| US7106149B2 (en) | Switchable tuneable bandpass filter with optimized frequency response | |
| KR920002761B1 (en) | Tuning system for a multiband tv receiver | |
| US4573211A (en) | Two-circuit resonant bandpass filter for television tuners | |
| US3794924A (en) | Multi-channel wave receiver | |
| US4598425A (en) | All-channel television tuning system | |
| US3702968A (en) | Am-fm radio receiver having novel rf input circuit | |
| JPH0730456A (en) | Television tuner | |
| JP3614614B2 (en) | Television signal receiving tuner | |
| EP0961407B1 (en) | Television tuner | |
| KR910009483Y1 (en) | Low pass filter of bs tuner | |
| KR940003408Y1 (en) | Uhf/vhf switching filter for tv receiver | |
| KR820000768B1 (en) | Very high frequency tuner |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |