Multiband scanning radio receiver using frequency synthesizer

• US 4,179,662 A
• Filed: 08/04/1978
• Issued: 12/18/1979
• Est. Priority Date: 03/14/1974
• Status: Expired due to Term

• Current Assignee: Masco Corporation Of Indiana (Masco Corporation)
• Original Assignee: Masco Corporation Of Indiana (Masco Corporation)
• Inventors: Pflasterer, Peter W.
• Primary Examiner(s): Safourek, Benedict V.
• Assistant Examiner(s): Chin, Tommy P.
• Application Number:
  US05/931,131
• Time in Patent Office: 501 Days
• Field of Search: 325/470, 325/335, 325/453, 325/455, 325/458, 325/459, 325/460, 325/468, 325/469, 325/421, 325/464, 325/419, 334/18, 331/1 A, 331/1 R, 331/2, 331/4
• US Class Current: 455/165.1
• CPC Class Codes: H03J 5/0281 the digital values being held in an auxiliary non erasable memory
• CPC Class Codes: H03J 7/285 the counter or frequency divider being used in a phase locked loop

Abstract

A scanning FM monitor receiver is disclosed which is of the superheterodyne type and is capable of scanning and receiving a plurality of channels on a plurality of bands. The receiver incorporates a phase-locked-loop frequency synthesizer which eliminates the need for crystals for every channel. The input data that the synthesizer requires to develop the individual preselected frequencies is provided by a random access memory that is programmed by the user for the frequencies desired. Indicator lamps on the receiver illuminate when a channel is being scanned and also provides a visual accuracy check when an operator programs the random access memory with the data codes for producing the various frequencies.

Claims

1. A signal seeking receiver for automatically scanning and monitoring a plurality of channels of predetermined radio frequencies lying in a low RF band and in a plurality of separate and spaced apart higher RF bands, and for tuning a received channel signal having a frequency corresponding to one of said channels, said receiver comprising:

a separate RF section uniquely associated with each of said RF bands and including a RF amplifier and a RF band mixer, each of said RF band mixers having an output;

band switch logic means for producing a band logic signal indicating that a channel being scanned is within a particular one of said RF bands for energizing only one of said RF sections corresponding to said band logic signal;

phase-locked-loop frequency synthesizing means responsive to a predetermined combination of input signals applied thereto for generating a synthesized frequency beating signal at an output of said frequency synthesizing means;

programmable memory means connected to said frequency synthesizing means for storing various preselected combinations of said input signals at predetermined addresses;

means for programming said memory means to enter said various preselected combinations of input signals at predetermined addresses in said memory means, said programming means including means for manually and separately producing each of said various combinations of signals;

means connected to said memory means for selectively addressing said memory means to thereby cause a selected combination of input signals to be applied to said frequency synthesizing means;

a first supplemental mixer connected between the output of said frequency synthesizing means and a first one of said RF band mixers;

a second supplemental mixer connected between the output of said frequency synthesizing means and a second one of said RF band mixers, a third one of said RF band mixers directly connected to the output of said frequency synthesizing means for receiving said synthesized frequency beating signal;

oscillator means responsive to said band logic signal for providing a substantially constant oscillator frequency signal to at least one of said supplemental mixers when said band signal indicates that the channel being scanned is within one of said RF bands corresponding to said first or said second supplemental mixer;

first frequency multiplier means connected between said oscillator means and said first supplemental mixer for multiplying said oscillator signal by a first factor;

second frequency multiplier means connected between said oscillator means and said second supplemental mixer for multiplying said oscillator signal by a factor different from said first factor;

means responsive to said band logic signal for energizing only one of said RF sections to tune a received channel signal and provide an intermediate signal at the output of the RF band mixer of said energized RF section;

an IF section directly connected in common to the output of each of said RF band mixers, and including an IF amplifier for amplifying said intermediate signal;

detector means coupled to said IF amplifier for producing an audio signal in response to said intermediate signal;

an audio amplifier connected to said detector means for driving an audio speaker with said audio signal; and

means for producing an inhibiting signal and for disabiling said audio amplifier when a channel signal is not being received.

2. A receiver as defined in claim 1 further including means for activating said addressing means for sequencing among said preselected combinations of input signals to scan said channels, said activating means being disabled in response to receiving said inhibiting signal, and being subsequently reactivated for resuming scanning of said channels in response to the termination of said inhibiting signal indicating said channel is no longer being received.

3. A receiver as defined in claim 1 wherein said RF section including said third RF band mixer directly connected to the output of said frequency synthesizing means is uniquely associated with said low RF band.