GB1456643A - Decoding a coded signal - Google Patents
Decoding a coded signalInfo
- Publication number
- GB1456643A GB1456643A GB5303873A GB5303873A GB1456643A GB 1456643 A GB1456643 A GB 1456643A GB 5303873 A GB5303873 A GB 5303873A GB 5303873 A GB5303873 A GB 5303873A GB 1456643 A GB1456643 A GB 1456643A
- Authority
- GB
- United Kingdom
- Prior art keywords
- address
- bit
- channel
- command
- secure
- 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
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/10—Adaptations for transmission by electrical cable
-
- 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
- H03J5/246—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 using electronic means
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/16—Analogue secrecy systems; Analogue subscription systems
- H04N7/173—Analogue secrecy systems; Analogue subscription systems with two-way working, e.g. subscriber sending a programme selection signal
- H04N2007/1739—Analogue secrecy systems; Analogue subscription systems with two-way working, e.g. subscriber sending a programme selection signal the upstream communication being transmitted via a separate link, e.g. telephone line
Abstract
1456643 Selective signalling COLUMBIA PICTURES INDUSTRIES Inc 15 Nov 1973 [15 Nov 1972 (2)] 53038/73 Heading G4H [Also in Division H4] An address portion of a bit serial coded signal is compared with a serial reference address from one output of a read-only memory which (assuming agreement) also produces at least one enabling signal to enable decoding of a command portion of the serial coded signal. Fig. 1 shows a converter-tuner unit of a subscription TV system. The cable at the left carries standard broadcast TV signals, and a plurality of secure TV channels (each modulated on to a respective carrier) and a command carrier. A multi-bit address followed by an operation bit and command bits may be modulated on to the command carrier using a tone in split phase mark fashion, viz. a transition between presence and absence of the tone at each bit cell boundary and such a transition in the middle of each "1" bit cell. The address, operation and command bits are amplified and detected, with A.G.C., at 20, 29, 35 to feed the tone signals to logic circuitry 30 (see below) which, if it recognizes the address as being that of this converter-tuner, decodes the remaining bits to specify for each secure TV channel whether it may be received. A diode switch 10 is used to pass standard or secure channel TV signals to the TV receiver. Assuming that one of the secure channels is selected by a selector switch 38 and reception of it is permitted by the logic circuitry 30, the signals for all the secure channels, passed by a band-pass filter 40, go to a varactor tuned filter which selects the required secure channel (under control of the selector switch 38) for mixing in a double balanced mixer 60 with a frequency (lower than that of the channel carrier) from a local oscillator. The local oscillator uses a common transistor controlled by one of a plurality of crystals (one per channel) selected by diode switches controlled by the selector switch 38. The output of mixer 60 goes via a channel 12 amplifier 90 and filter 80 to the receiver (via diode switch 10). Local oscillator frequency harmonics which are close to a secure channel carrier frequency are cancelled by a resonant circuit providing anti-phase feedback from filter 50 to filter 40. Details of logic circuitry 30 (including address recognition).-The tone sequence representing the address, operation and command bits passes to a monostable tone burst detector 100 followed by an edge detector 110 and a data and clock converter 120 which supplies data pulses and a bit clock. The bit clock drives a counter 140 which addresses a read-only memory 150. During the address reception, memory 150 enables a compare (EX-OR) gate 160 and a data change latch 190, and supplies the address of the unit to compare gate 160 serially-by-bit for comparison with the address received. Any mismatch resets the counter 140, except that this is inhibited by the data change latch if the address is all zero (which addresses all the tunerconverter units). If the counter is not reset, then for command bit reception, the memory 150 in conjunction with the operation bit sets an operation bit latch 200 to partially enable a latch 210, 220 for each channel, these being also partially enabled in turn by memory 150 directly, to receive respective command bits. The outputs of these latches go via capacitor storage to the selector switch which can select one of them. Resetting at the end of the message is performed by a monostable data presence detector 130 responsive to the edge detector 110.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US05/306,869 US3935534A (en) | 1972-11-15 | 1972-11-15 | Converter-tuner for information transmission system |
US00306830A US3835387A (en) | 1972-11-15 | 1972-11-15 | Control circuitry for information transmission system |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1456643A true GB1456643A (en) | 1976-11-24 |
Family
ID=26975391
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB5303873A Expired GB1456643A (en) | 1972-11-15 | 1973-11-15 | Decoding a coded signal |
Country Status (2)
Country | Link |
---|---|
GB (1) | GB1456643A (en) |
IL (1) | IL43706A0 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2454736A1 (en) * | 1979-04-16 | 1980-11-14 | Yarbrough Charles | METHOD AND APPARATUS FOR SELECTIVE RECORDING OF A BROADCAST OF A SOUND AND / OR VISUAL PROGRAM |
GB2156556A (en) * | 1984-03-23 | 1985-10-09 | Philips Electronic Associated | Electrical circuit unit and circuit arrangement including a plurality of such units |
-
1973
- 1973-11-15 GB GB5303873A patent/GB1456643A/en not_active Expired
- 1973-11-26 IL IL43706A patent/IL43706A0/en unknown
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2454736A1 (en) * | 1979-04-16 | 1980-11-14 | Yarbrough Charles | METHOD AND APPARATUS FOR SELECTIVE RECORDING OF A BROADCAST OF A SOUND AND / OR VISUAL PROGRAM |
GB2156556A (en) * | 1984-03-23 | 1985-10-09 | Philips Electronic Associated | Electrical circuit unit and circuit arrangement including a plurality of such units |
Also Published As
Publication number | Publication date |
---|---|
IL43706A0 (en) | 1974-05-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4481489A (en) | Binary signal modulating circuitry for frequency modulated transmitters | |
US4408349A (en) | Receiver provided with a frequency synthesizer capable of storing fine tuning information | |
US3497813A (en) | Multi-frequency receiver with automatic channel selection and priority channel monitoring | |
US4910467A (en) | Method and apparatus for decoding a quadrature modulated signal | |
US4723310A (en) | Digital data transmission system by coherent light wave modulation | |
ES294582A1 (en) | Multilevel vestigial sideband suppressed carrier data transmission system | |
US5179446A (en) | Radio transmitting and receiving circuits of a video camera having a detached view finder | |
JPS627728B2 (en) | ||
US4123715A (en) | Program apparatus for radio receiver using frequency synthesizer | |
US4305157A (en) | Tuning circuit using a phase-locked loop | |
US4606049A (en) | Remote transmitter control system | |
GB1456643A (en) | Decoding a coded signal | |
KR920017379A (en) | Receiver automatic frequency control method and apparatus for implementing the method | |
US2507735A (en) | Automatic tuning control apparatus | |
US4047227A (en) | Auxiliary signal processing circuit | |
GB1146865A (en) | Improvements in or relating to synchrodyne receivers | |
US6643499B1 (en) | Apparatus and method for controlling a phase-locked loop circuit | |
US4380826A (en) | Control system for channel selection | |
US4270217A (en) | Processor controlled, service selecting, AM/FM scanning radio receiver | |
GB1024250A (en) | Data transmission system by phase leading and lagging | |
US4398304A (en) | Scanning radio receiver including detector circuit for AM and FM reception | |
US4654705A (en) | Two channel audio scrambling system | |
US4389644A (en) | Asynchronous type multichannel signal processing system | |
CA1136052A (en) | Multiplexed central dictation system | |
JP2967025B2 (en) | Wireless beacon receiver |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PS | Patent sealed [section 19, patents act 1949] | ||
PCNP | Patent ceased through non-payment of renewal fee |