REMOTE CONTROL SYSTEM FOR OPERATION OVER SAME AUDIOCHANNEL PROVIDING VOICE SIGNALS BETWEEN REMOTE STATION AND BASE STATION

• US 3,577,080 A
• Filed: 12/20/1968
• Issued: 05/04/1971
• Est. Priority Date: 12/20/1968
• Status: Expired due to Term

• Current Assignee: Gary A. Cannalte
• Original Assignee: Gary A. Cannalte
• Inventors: Cannalte, Gary A.
• Application Number:
  US04/785,526
• Time in Patent Office: 865 Days
• US Class Current: 340/13.36
• CPC Class Codes: G08C 19/12 in which the signal transmitted is frequency or phase of ac

Abstract

Remote control system for controlling radio at base station from remote point over single audio channel which provides voice signals between remote and base stations, and which does not require DC continuity and operates within a fixed maximum frequency. A short burst of high amplitude guard tone is applied over the channel from the remote station to the base station to actuate a control at the base station which renders the controls thereat operative and blocks transmission of audiosignals from the base station to the channel. The remote station then applies lower amplitude tones to the audiochannel to actuate controls at the base station, with guard tone being applied continuously at low level during application of audio signals from the remote station to the base station. The base station responds to termination of tone signals (or to disconnect tones) to provide disconnect action, reset the controls and permit the base station to apply signals to the audio channel.

Claims

1. A remote control system for providing signals over an audio channel wherein the efficiency of transmission decreases above a given frequency, including in combination:

oscillator means for producing guard tone oscillations at a first frequency below the given frequency and at a first amplitude level, said oscillator means selectively producing tone oscillations at a number of frequencies below the given frequency and different from the first frequency and at a second amplitude level below said first amplitude level, control means including timer means and control switch means connected to said timer means initiating remote control operation, said timer means including a first portion for producing a first control during a first time period and a second portion for producing a second control during a second time period following said first time period, and means connecting said timer means to said oscillator means for applying said first and second controls thereto, said control switch meAns being operable to initiate operation of said timer means to cause said oscillator means to provide guard tone oscillations of said first amplitude level in response to said first control during said first time period and to cause said oscillator means to provide oscillations at a different frequency and at said second amplitude level in response to said second control during said second time period.

2. The remote control system of claim 1 wherein said oscillator means includes a first portion for producing guard tone oscillations and a second portion for selectively producing tone oscillations of different frequencies.

3. The system of claim 2 wherein said control means includes selector means connected to said second portion of said oscillator means to control the frequency of oscillations produced thereby.

4. The system of claim 1 wherein said oscillator means includes a tuned circuit having a coil, and further switch means connected to said coil to provide current through said coil and to block the flow of current therethrough to thereby produce an oscillation in said tuned circuit to start said oscillator means.

5. The system of claim 4 wherein said control means includes a plurality of capacitors and selector means for selectively connecting said capacitors to said tuned circuit for controlling the frequency of said oscillator means.

6. The system of claim 1 wherein said oscillator means includes attenuator means for reducing the amplitude of said guard tone oscillations, and said first portion of said timer means applies said first control to said attenuator means to inhibit the same so that said guard tone oscillations are applied to the audio channel at said first amplitude level during the first time period.

7. The remote control system of claim 1 wherein said oscillator means includes muting means and attenuator means coupled to said timer means for controlling the guard tone oscillations, and wherein said timer means inhibits said muting means and said attenuator means during the first time period to provide guard tone oscillations and inhibits said muting means at the end of the second time period so that guard tone oscillations are provided at reduced level.

8. The remote control system of claim 7 wherein said second portion of said timer means actuates said muting means to block the transmission of guard tone during the second time period.

9. The remote control system of claim 1 including further means responsive to release of said control switch means for causing said oscillator means to provide tones which alternate between two different frequencies for disconnect action.

10. The remote control system of claim 9 wherein said further means includes a timer operated in response to release of said switch means, astable means coupled to said timer, means coupling said timer to said oscillator means to cause operation thereof for a third time period, and means coupling said astable means to said oscillator means for alternately changing the frequency of the tone produced thereby between a pair of frequencies.

11. A remote control system for applying control signals from a remote station to a base station over a channel on which audiosignals are applied from said remote station to said base station and from said base station to said remote station, and wherein the efficiency of transmission of the channel decreases above a given frequency, with audio signals above a given amplitude level being permitted on said audiochannel for only a limited time duration, said system including in combination:

apparatus at the remote station including generator means for providing first oscillations of a first frequency at an amplitude level above said given amplitude level, and for providing second oscillations at a frequency different from said first frequency at an amplitude level below said given amplitude level, and control means for selectively applying said first oscillations to the audiochannel for a first time duration less than said limited time duration and for applying second oscillations thereto following said first oscillations; and

apparatus at the base station including first means for applying audiosignals to the audiochannel, second means for receiving signals from the audiochannel, and means coupled to said second means and responsive to said first oscillations for rendering said first means inoperative to apply signals to the audiochannel, so that said second oscillations are applied to the audiochannel at the remote station in the absence of signals applied thereto from the base station.

12. The remote control system of claim 11 wherein said generator means at the remote station includes means for changing the frequency of said second oscillations so that control signals of different frequencies are produced, and including detector means at the base station responsive to the frequency of said second oscillations to provide different control operations.

13. The remote control system of claim 12 including gate means at the base station responsive to said first oscillations for applying the second oscillations to said detector means.

14. The remote control system of claim 12 including means at the base station coupled to said second means and responsive to the termination of said first and second oscillations to provide disconnect action to enable said first means to apply audiosignals to the audiochannel and to condition said detector means for a further control action.

15. The remote control system of claim 11 including push-to-talk switch means at the remote station connected to said control means and causing operation thereof following the application of second oscillations thereto and for the duration of the operation of said push-to-talk switch means to apply to the audiochannel oscillations of the first frequency at an amplitude level below said given amplitude level.

16. The remote control system of claim 11 wherein said control means causes said generator means to apply to the audiochannel at the termination of the control signal oscillations alternating between second and third frequencies, and wherein said second means at the base station includes detector means responsive to said oscillations alternating between said second and third frequencies to provide disconnect action at the base station and thereby permit said first means to apply audiosignals to the audio channel.

17. The remote control system of claim 11 wherein said apparatus at said base station includes amplifier means coupled to said second means and having selective means tuned to the frequency of said first oscillations to increase the gain at such frequency, first detector means coupled to said amplifier means for providing a control voltage in response to said first oscillations, second detector means responsive to said second oscillations to provide control action in accordance with the frequency of said second oscillations, and gate means coupling said amplifier means to said second detector means and responsive to said control voltage for passing to said second detector means said second oscillations which follow said first oscillations.

18. The remote control system of claim 17 including switch means responsive to said control voltage for disabling said selective means to increase the gain of said amplifier means for said second oscillations. 19 The remote control system of claim 17 including automatic gain control means coupled to said amplifier means for controlling the gain thereof in accordance with the signal at the output of said amplifier means.

20. The remote control system of claim 19 wherein said automatic gain control means includes a first relatively slow acting portion responsive to the level of the oscillations in said amplifier means, and a second relatively fast acting portion responsive to the level of the oscillations in said first detector means.