GB1145706A - An automatic frequency control system - Google Patents
An automatic frequency control systemInfo
- Publication number
- GB1145706A GB1145706A GB46624/65A GB4662465A GB1145706A GB 1145706 A GB1145706 A GB 1145706A GB 46624/65 A GB46624/65 A GB 46624/65A GB 4662465 A GB4662465 A GB 4662465A GB 1145706 A GB1145706 A GB 1145706A
- Authority
- GB
- United Kingdom
- Prior art keywords
- transistors
- filter
- oscillator
- frequency
- output
- 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
- 239000003990 capacitor Substances 0.000 abstract 1
- 238000005070 sampling Methods 0.000 abstract 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/04—Synchronising
- H04N5/12—Devices in which the synchronising signals are only operative if a phase difference occurs between synchronising and synchronised scanning devices, e.g. flywheel synchronising
- H04N5/126—Devices in which the synchronising signals are only operative if a phase difference occurs between synchronising and synchronised scanning devices, e.g. flywheel synchronising whereby the synchronisation signal indirectly commands a frequency generator
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
Abstract
1,145,706. Automatic frequency control; transistor circuits. THORN ELECTRONICS Ltd. 2 Nov., 1966 [3 Nov., 1965], No. 46624/65. Headings H3A and H3T. In an automatic frequency control system in which an oscillator is compared with a reference signal to produce an output at point X which is fed through a filter R1, R2, C2 to control the oscillator frequency, an amplifier is connected in parallel with the filter to reduce the time constant of the filter circuit when slip occurs between the two frequencies. The amplifier comprises transistors VT1 . . . VT4. When the two signals are at the same frequency, the base collector junctions of transistors VT1, VT2 are forward biased holding their emitters to near base potential so that these transistors and the two following transistors VT3, VT4 are cut-off. Under this condition the output from the phase comparator 4 is fed via the low pass filter R1, R2, C2 to control the frequency of the oscillator 1 so as to correct the phase difference. When slip occurs, an A.C. output at the slip frequency is produced by the phase comparator and this results in the capacitors C3, C4 charging until the collectors, of VT1, VT2 are at about 0 volts and - V volts respectively. Under these conditions the transistors all become conductive and the signal is fed from point X to point Y via the amplifier, thus reducing the effective time constant of the filter. The R circuit is applied to a television line synchronization system in which a circuit 3 produces trapezoidal pulses from the oscillator output, and circuit 5 produces sampling pulses from the reference signal.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB46624/65A GB1145706A (en) | 1965-11-03 | 1965-11-03 | An automatic frequency control system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB46624/65A GB1145706A (en) | 1965-11-03 | 1965-11-03 | An automatic frequency control system |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1145706A true GB1145706A (en) | 1969-03-19 |
Family
ID=10441974
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB46624/65A Expired GB1145706A (en) | 1965-11-03 | 1965-11-03 | An automatic frequency control system |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB1145706A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2123229A (en) * | 1982-06-28 | 1984-01-25 | Gen Electric | Control circuits for phase locked loops |
EP0519562A2 (en) * | 1991-06-21 | 1992-12-23 | Koninklijke Philips Electronics N.V. | Phase-locked loop receiver |
EP0730071A1 (en) * | 1995-03-03 | 1996-09-04 | Siemens Aktiengesellschaft | Anti-theft system for a motor vehicle |
-
1965
- 1965-11-03 GB GB46624/65A patent/GB1145706A/en not_active Expired
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2123229A (en) * | 1982-06-28 | 1984-01-25 | Gen Electric | Control circuits for phase locked loops |
US4506233A (en) * | 1982-06-28 | 1985-03-19 | General Electric Company | Bandwidth control circuit for a phase locked loop |
EP0519562A2 (en) * | 1991-06-21 | 1992-12-23 | Koninklijke Philips Electronics N.V. | Phase-locked loop receiver |
EP0519562A3 (en) * | 1991-06-21 | 1993-08-04 | N.V. Philips' Gloeilampenfabrieken | Phase-locked loop receiver |
EP0730071A1 (en) * | 1995-03-03 | 1996-09-04 | Siemens Aktiengesellschaft | Anti-theft system for a motor vehicle |
US5889471A (en) * | 1995-03-03 | 1999-03-30 | Siemens Aktiengesellschaft | Anti-theft system for a motor vehicle |
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