RADIO TRANSMITTER-RECEIVED INCLUDING MEANS FOR AUTOMATICALLY ADJUSTING THE TRANSMISSION LEVEL

• US 3,732,496 A
• Filed: 10/05/1970
• Issued: 05/08/1973
• Est. Priority Date: 10/03/1969
• Status: Expired due to Term

• Current Assignee: Marcel Louis Boyer
• Original Assignee: Marcel Louis Boyer
• Inventors: Boyer, Marcel Louis
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US05/078,100
• Time in Patent Office: 946 Days
• Field of Search: 325/15,21,62,183 343/6.5R,6.5LC,6.5SS,7.5,177
• US Class Current: 455/69
• CPC Class Codes: H04B 1/40 Circuits
• CPC Class Codes: H04W 52/362 Aspects of the step size
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range

Abstract

A radio transmitter-receiver including means for automatically adjusting the transmission level so as to bring the reception level in an associated transmitter-receiver receiving such transmission into a range limited at a lower end by a reference reception level by means of an attenuator providing a stepped variable attenuation level and controlled by a signal frequency received from the associated transmitter-receiver; and means for transmitting a signal frequency selected from a set of such frequencies in accordance with the level at which a transmission from the associated transmitter-receiver is received by means of a selector device comprising a set of threshold circuits corresponding to thresholds between said reference reception level and a saturation level limiting the range at an upper end.

Claims

1. A radio transmitter-receiver including a transmitter section and a receiver section, control means for adjusting the level of transmission of said transmitter section to another transmitterreceiver in accordance with one of a plurality of different level signals received from that other transmitter-receiver indicative of the level at which the transmission is received, said transmitter section including signalling means for transmitting to said other transmitter-receiver one of a plurality of different level signals comprising a selected one of a set of signal frequencies each significant of a preselected range of reception levels, said control means including filter circuit means for identifying the signal frequency of a received level signal and variable attenuator means responsive to the detection of a particular signal frequency for attenuating the transmission level of said transmitter section by a predetermined amount associated with that frequency, wherein said signalling means includes threshold circuit means connected to sample the instantaneous level at which the transmission from the other transmitterreceiver is received for providing an output significant of a preselected range in which the instantaneous level lies, and frequency selector means arranged to select an individual signal frequency for transmission to the other transmitter-receiver in accordance with the output of said threshold circuit means, said threshold circuit means having its input connected to the output of a radio frequency amplifier of the receiver section through a rectifying circuit and said frequency selector means including first logic circuit means connected to receive the output of said threshold circuit means for controlling operation of a switching unit for selecting said level frequency, said control means including second logic circuit means connected to receive the output of said filter circuit means which is connected to receive the level signal from the other transmitter-receiver via a band pass filter, said second logic circuit means providing an output applied to the variable attenuator to select the amount of attenuation associated wiTh the identified signal frequency and including a respective first bistable circuit associated with each instantaneous level range and a first AND gate associated with each first bistable circuit, the outputs of said first AND gates being connected to respective inputs of a first OR gate providing at its output an authorization signal for said first logic circuit means.

2. A transmitter-receiver as claimed in claim 1, wherein said filter circuit means includes a filter for each signal frequency connected in series with a respective rectifier and threshold circuit to a respective input of said second logic circuit means, all threshold circuits having the same threshold value.

3. A transmitter-receiver as claimed in claim 1, wherein said frequency selector means includes a set of fixed frequency oscillators each providing one individual signal frequency through said switching unit to a modulator of the transmitter section.

4. A transmitter-receiver as claimed in claim 3 wherein the receiver section is a heterodyne receiver including a radio frequency amplifier and an intermediate frequency amplifier, part of said threshold circuit means being connected to receive the radio frequency amplifier output and the remainder being connected to receive the intermediate frequency amplifier output.

5. A transmitter-receiver as claimed in claim 4, wherein said threshold circuit means includes respective threshold circuits corresponding to each of a preselected set of reception levels.

6. A transmitter-receiver as claimed in claim 5, wherein selected threshold circuits are connected to receive the radio frequency amplifier output, the remainder of said threshold circuits being connected to receive the intermediate frequency amplifier output.

7. A transmitter-receiver as claimed in claim 6, wherein said signalling means includes signal generators providing a plurality of signal frequencies which lie in a narrow band at one end of a modulation band in which they are transmitted, the maximum depth of modulation employed for this transmission being 10%.

8. A transmitter-receiver as claimed in claim 7, wherein said transmitter section includes means for transmitting said signal frequencies in double modulation by means of an auxiliary sub-carrier, said signal frequencies being located at the upper end of the modulation band.

9. A transmitter-receiver as claimed in claim 8, wherein said first logic circuit means of said frequency selector means includes a respective second bistable circuit associated with each of the thresholds between adjacent instantaneous level ranges and a respective second AND-gate associated with each of the ranges, each second AND-gate being connected to receive selected second bistable circuit outputs and the set of second AND-gates providing the switching unit for selecting the level frequency.

10. A transmitter-receiver as claimed in claim 9, wherein the output of second AND-gate is connected to energize a respective fixed frequency oscillator.

11. A transmitter-receive as claimed in claim 10, including a manually operable device for selecting one of the signal frequencies.

12. A transmitter-receive as claimed in claim 11, wherein said manually operable device is a switch selectively connecting a voltage source to a second input of a first OR-gate whose other input is connected to the output of the second AND-gate corresponding to that one signal frequency, the second OR-gate output signal serving to select that one signal frequency either in response to operation of that second AND-gate or in response to operation of the switch.

13. A transmitter-receiver as claimed in claim 12, wherein each input of said second logic circuit means consists of the input of one of said first bistable circuits.

14. A transmitter-receiver as claimed in claim 13, including a noise discriminator circuit with an input connected in parallel with that of said filter circuit means and arranged to inhibit operation of said second logIc circuit means in response to a predetermined noise level.

15. A transmitter-receiver as claimed in claim 14, wherein said noise discriminator circuit comprises a rectifier whose input constitutes the circuit input and whose output is connected to the input of each first AND-gate of said first logic circuit means.

16. A transmitter-receiver as claimed in claim 12, wherein said second logic circuit means includes means for controlling the operation of switching circuitry connected to receive the outputs of at least one of the first AND-gates of said second logic circuit means through respective differentiator circuits.

17. A transmitter-receiver as claimed in claim 16, wherein said switching circuitry includes three third bistable circuits each connected to receive a respective first AND-gate output through a respective differentiator circuit.

18. A transmitter-receiver as claimed in claim 17, wherein the third bistable circuit outputs are connected to the input of a digital-to analog converter whose output is applied via a direct current amplifier to said variable attenuator means.

19. A transmitter-receiver as claimed in claim 18, wherein the output of each third bistable circuit is connected to an individual attenuator circuit in said variable attenuator means.

20. A transmitter-receiver as claimed in claim 17, wherein each third bistable circuit is connected to receive said authorization signal so as to inhibit said third bistable circuits operating in response to said differentiator circuit outputs when the authorization signal is not present.