Patent EP0179620A2 successfully refreshed from Google Patents.
EP0179620A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Automatic fine tuning system
Assignee: RCA Licensing Corp
•
Filing: 1985-10-17
•
Granted: —
•
Expires: 2005-10-17
Abstract
Abstract In automatic fine tuning (AFT) apparatus in a superheterodyne receiver, the IF carrier is selectively filtered and is applied to a signal multiplier arrangement (156). An auxiliary heterodyning signal (158) is also applied to the multiplier arrangement so as to produce an offset signal having a frequency proportional to the frequency difference between the IF carrier and the heterodyning signal. The offset signal is applied to a microprocessor (112) programmed to produce a control signal for controlling the local oscillator (106) to reduce frequency deviation between the IF signal and a nominal IF frequency.
Inventors
- 👤 Charles Martin Wine
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 20:38
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/44; H04N5/50; H03; H03J; H03J7/00; H03J7/02; H03J7/04; H03J7/06
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
202 words
Apparatus for fine tuning a superheterodyne receiver, said receiver including controllable local oscillator (LO) means (106) for producing a local oscillator signal and having a control input; intermediate frequency (IF) amplifier means (108) for processing an IF signal; and automatic fine tuning (AFT) control means (158,156,134,140, 116,112) for automatically controlling said LO means so as to reduce a frequency deviation between said IF frequency and a predetermined nominal IF frequency, said apparatus characterized by: auxiliary heterodyne oscillator means (158) for providing a heterodyning signal; carrier selective filter means (134,140) coupled to said IF amplifier for deriving a carrier representative signal at the IF carrier frequency; signal multiplier means (156) coupled to said heterodyne oscillator and said carrier selective filter means for producing an offset frequency signal proportional to the difference frequency between said carrier representative signal and said auxiliary heterodyning signal; a source of a clock signal (116); and control means (112) coupled to said signal multiplier means for receiving said offset frequency signal and to said source of a clock signal for receiving said clock signal for applying a control signal representative of said difference frequency to said controllable LO means control input in a sense to reduce said frequency deviation.
Claim 2
Dependent Claim
202 words
Apparatus for fine tuning a superheterodyne receiver, said receiver including controllable local oscillator (LO) means (106) for producing a local oscillator signal and having a control input; intermediate frequency (IF) amplifier means (108) for processing an IF signal; and automatic fine tuning (AFT) control means (158,156,134,140, 116,112) for automatically controlling said LO means so as to reduce a frequency deviation between said IF frequency and a predetermined nominal IF frequency, said apparatus characterized by: auxiliary heterodyne oscillator means (158) for providing a heterodyning signal; carrier selective filter means (134,140) coupled to said IF amplifier for deriving a carrier representative signal at the IF carrier frequency; signal multiplier means (156) coupled to said heterodyne oscillator and said carrier selective filter means for producing an offset frequency signal proportional to the difference frequency between said carrier representative signal and said auxiliary heterodyning signal; a source of a clock signal (116); and control means (112) coupled to said signal multiplier means for receiving said offset frequency signal and to said source of a clock signal for receiving said clock signal for applying a control signal representative of said difference frequency to said controllable LO means control input in a sense to reduce said frequency deviation.
Claim 3
Dependent Claim
40 words
Apparatus as recited in Claim 1 wherein said carrier selective filter means (134,140) comprises narrow band filter means (140) for exhibiting relatively low attenuation at said IF carrier frequency and relatively high attenuation at sideband frequencies of said IF signal.
Claim 4
Dependent Claim
23 words
Apparatus as recited in Claim 1 or 2 wherein the frequency of said auxilary heterodyning signal is substantially greater than said difference frequency.
Claim 5
Dependent Claim
80 words
Apparatus as recited in Claim 1, 2 or 3 wherein said signal multiplier means includes first signal multiplier means (142) coupled to said carrier filter means (134,140) for detecting the amplitude modulation of said IF signal to produce a baseband video signal; and second signal multiplier means (156) coupled to said heterodyne oscillator and to said carrier filter means for producing an offset frequency signal proportional to the difference frequency between said carrier representative signal and said auxilary heterodyning signal.
Claim 6
Dependent Claim
21 words
Apparatus as recited in Claim 4 wherein said first and second signal multiplier means are incorporated in a single integrated circuit.
Claim 7
Dependent Claim
59 words
Apparatus as recited in Claim 1, 2, 3, 4 or 5 wherein said control means comprises microprocessor means for generating an output signal representative of said frequency deviation and signal integrating means coupled between said microprocessor means and said LO means control input for integrating said output signal and thereby producing said control signal representative of said frequency deviation.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.