REMOTE CONTROL RECEIVER USING A PHASE LOCKED LOOP

• US 3,701,103 A
• Filed: 04/07/1971
• Issued: 10/24/1972
• Est. Priority Date: 04/07/1971
• Status: Expired due to Term

• Current Assignee: Donald A. Wison, William J. Padgett
• Original Assignee: Donald A. Wison, William J. Padgett
• Inventors: Padgett, William J., Wison, Donald A.
• Primary Examiner(s): Mayer, Albert J.
• Application Number:
  US05/132,129
• Time in Patent Office: 566 Days
• Field of Search: 325/346,349,417,419,420,423,47,465,468 329/122,123,136 340/147,148,149,156,160,180,170-172 179/15AP,15BD,15BL,15BY,15FD 324/82
• US Class Current: 367/199
• CPC Class Codes: G08C 19/12 in which the signal transmitted is frequency or phase of ac

Abstract

A remote control receiver selectively responsive to a plurality of different frequency command signals to control corresponding different command functions. The receiver uses a phase locked loop including a controlled oscillator having a variable frequency output which is compared in a phase comparator with the received command signal. The detected phase difference generates an error voltage which shifts the oscillator from its quiescent frequency to the incoming frequency and phase locks the controlled oscillator to the command signal. The error voltage also activates only one of several DC voltage comparators, with a different comparator corresponding to each command function. Each comparator includes a means of establishing a reference voltage and means for activating a driver stage for the corresponding remote function when the error voltage generated by the phase comparator to lock the receiver to a particular command frequency and equals the corresponding reference voltage.

Claims

1. In a remote control system including a transmitter for generating a command signal having a selectable, one of at least three frequencies and a receiver for actuating a different remote element for each received command signal of different frequency, a decoder for the receiver, comprising;

phase locked loop means for tracking the received command signal including controlled oscillator means for generating an oscillatory signal having a frequency proportional to the amplitude of an error signal, and phase comparator means for comparing the phase difference between the received command signal and the oscillatory signal to generate said error signal, each selectable frequency of said command signal producing a unique amplitude of said error signal when the phase locked loop locks on the received command signal; and

a plurality of detector means coupled to said phase comparator means for individually actuating an associated remote element, each detector means including level comparator means responsive to a different one of said unique amplitudes for acTuating the associated remote element.

2. The apparatus of claim 1 wherein each detector means comprises a level comparator having first and second inputs and an output, means coupled to one of said inputs for establishing a reference signal thereon, means coupling said error signal to the other said inputs, said level detector producing a drive signal at said output having a predetermined given first magnitude when the signals on said first and second inputs are equal and a magnitude different, in the same sense, from said given magnitude when the signal at the said other of said inputs is both greater and less than the reference signal on said one of said inputs and means responsive to said drive signal on said output to actuate the associated remote element only when said driver signal approaches said given first magnitude.

3. The apparatus of claim 2 wherein said level comparator comprises a differential amplifier having a pair of input terminals and a pair of output terminals, one of said input terminals comprising said first level detector input and the other of said input terminals comprising said second level detector input, and drive signal producing means coupled to said pair of output terminals for producing said drive signal on said level detector output.

4. The apparatus of claim 3 wherein said drive signal producing means comprises a four-diode bridge having a pair of diagonally opposite input junctions, a pair of diagonally opposite output junctions and a load impedance coupled between said pair of output junctions, said pair of input junctions being connected to respective ones of said pair of differential amplifier output terminals, one of said pair of output junctions comprising said level detector output.

5. The apparatus of claim 4 wherein said four-diode bridge comprises first, second, third and fourth diodes, means connecting said first diode, said load impedance and said second diode in that order in series between said differential amplifier output terminals, both of said first and second diodes being poled to conduct current from said first output terminal to said second output terminal in a given direction through said load impedance and means connecting in the order named, said third diode, said load impedance and said fourth diode in series between said output terminals, said third and fourth diodes being poled to conduct current from said second output terminal to said first output terminal in said given direction through said load impedance, one end of said load impedance comprising said level detector output.

6. The apparatus of claim 3 wherein said differential amplifier comprises first and second transistors each having base, emitter and collector electrodes and further including means coupling said emitter electrodes in common to a source of reference potential and respective load impedances coupling said collector electrodes to a source of operating potential the base electrodes of said first and second transistors comprising said pair of input terminals and the junction between said collector electrodes and said respective load impedance means comprising said pair of output terminals.

7. The apparatus of claim 5 further comprising a constant current source coupled in series between said common connected emitter electrodes and said reference potential.