RECEIVER TUNING SYSTEM

• US 3,736,513 A
• Filed: 06/28/1971
• Issued: 05/29/1973
• Est. Priority Date: 06/28/1971
• Status: Expired due to Term

• Current Assignee: Donald A. Wilson
• Original Assignee: Donald A. Wilson
• Inventors: Wilson, Donald A.
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US05/157,539
• Time in Patent Office: 701 Days
• Field of Search: 325/418-423,464,468-471 331/4,19,40,179 328/134 334/11,16,13,18,26
• US Class Current: 455/164.1
• CPC Class Codes: H03J 7/06 using counters or frequency dividers
• CPC Class Codes: H03J 7/28 using counters or frequency dividers

Abstract

A harmonic generator produces simulated station signals which are heterodyned in the mixer stage of a receiver. A local oscillator of the receiver is swept through its frequency bandwidth, producing an IF pulse each time the receiver tunes one of the simulated stations. The IF pulses are counted, and upon reaching a number preset on station selection switches, convert the sweep circuit to an AFC amplifier, maintaining the receiver tuned to a desired station frequency.

Claims

1. In a receiver having receiver local oscillator means for generating different frequency oscillations to tune the receiver to different tunable frequencies, receiver detector means responsive to received signals and said oscillations to produce detected signals, and utilization means coupled to said receiver detector means for utilizing in said receiver said detected signals, an automatic frequency selector, comprising:

generator means for generating a plurality of reference signals coupled to said receiver detector means and each having a different frequency representing said different tunable frequencies;

sweep means for sweeping the oscillations of said receiver local oscillator means through a band of frequencies to cause said receiver detector means to produce an output signal for each reference signal tuned by the receiver local oscillator means;

counter means coupled to said receiver detector means for counting said output signals; and

recognition means responsive to a predetermined count in said counter means for disabling said sweep means and maintaining a selected frequency.

2. The automatic frequency selector of claim 1 wherein said recognition means includes switch means actuable to select different predetermined counts, and circuit means for disabling said sweep means when the count from said counter means corresponds to the predetermined count set on said switch means.

3. The automatic frequency selector of claim 2 wherein said switch means includes a plurality of groups of individual switch elements in which at least one switch element in each group is actuated to select a predetermined count, and said circuit means includes a plurality of gate means each associated with a different one of said groups of switches, each gate means being actuated when the count in said counter means corresponds to the individual actuated switch element, and combining means responsive to actuation of all of said gate means for disabling said sweep means.

4. The automatic frequency selector of claim 2 wherein said switch means comprise a plurality of switch elements, said counter means comprises a ring counter having a plurality of stages, and said circuit means connects each stage of said ring counter to a different one of said switch elements.

5. The automatic frequency selector of claim 1 wherein said sweep means includes ramp means for generating a ramp signal for sweeping said local oscillator means until disabled by said recognition means, and hold means responsive when said ramp means is disabled for holding the instant value of said ramp signal to maintain said receiver tuned to the selected frequency.

6. The automatic frequency selector of claim 5 wherein said receiver includes AFC means for generating an AFC signal to lock said receiver to received signals adjacent the selected tunable frequency, and said hold means includes bias means for causing the signal value maintained by said hold means to follow said AFC signal.

7. The automatic frequency selector of claim 6 wherein said hold means includes a first amplifying device, capacitor means connected to said amplifying device for generatinG thereacross said ramp signal, power supply means coupled to said amplifying device for causing said amplifying device to charge said capacitor means, and said bias means is responsive to said predetermined count for converting said amplifying device to an AFC amplifier.

8. The automatic frequency selector of claim 5 including an adjustable voltage source, and reset means actuated when said automatic frequency selector is to begin operation for connecting said adjustable voltage source to said ramp means to establish the initial frequency tuned by said local oscillator means.

9. The automatic frequency selector of claim 8 wherein said reset means includes an additional reset section, and means connecting said additional reset section to said counter means to clear the count recorded therein.

10. The automatic frequency selector of claim 8 wherein said reset means includes an additional reset section, and means responsive to said additional reset section for enabling said generator means when said automatic frequency selector is to begin tuning said receiver.

11. The automatic frequency selectOr of claim 10 wherein said recognition means includes means responsive to said predetermined count for disabling said generator means.

12. The automatic frequency selector of claim 1 wherein said generator means comprises oscillator means for generating a primary frequency signal and a plurality of harmonic frequency signals spaced apart by said primary frequency, said harmonic frequency signals forming said plurality of reference signals.

13. The automatic frequency selector of claim 12 wherein said generator means includes differentiator means coupled between said oscillator means and said detector means for differentiating said harmonic frequency signals to produce reference signals of short time duration.

14. The automatic frequency selector of claim 13 wherein said generator means includes clipping diode means coupled to said differentiator means for eliminating differentiated harmonic frequency signals of predetermined polarity.

15. The automatic frequency selector of claim 1 including level trigger means coupled between said detector means and said counter means, said level trigger means producing a trigger pulse which is counted by said counter means when the level of said output signal from said detector means exceeds a predetermined minimum amplitude.

16. The automatic frequency selector of claim 15 wherein said detector means includes mixer means for heterodyning said received signals with said oscillations to produce IF signals and IF amplifying means responsive to said IF signals for producing said output signals which are coupled to said level trigger means.