ASYNCHRONOUS PULSE RECEIVER

• US 3,848,191 A
• Filed: 07/07/1972
• Issued: 11/12/1974
• Est. Priority Date: 07/07/1972
• Status: Expired due to Term

• Current Assignee: Leonard Hugo Anderson
• Original Assignee: Leonard Hugo Anderson
• Inventors: Anderson, Leonard Hugo
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Bookbinder, Marc E.
• Application Number:
  US05/269,537
• Time in Patent Office: 858 Days
• Field of Search: 325/326,397,400,401,402,408,479,482,410,473,478,323,324 178/68,88 343/5AG,7A,17.1R 179/15BA,15BS
• US Class Current: 375/345
• CPC Class Codes: G01S 7/28 Details of pulse systems
• CPC Class Codes: G01S 7/34 Gain of receiver varied automatically during pulse-recurrence period, e.g. anti-clutter gain control

Abstract

The use of a broad-band, amplitude-limited IF amplifier, whose gain is controlled in accordance with a fed-back AGC noise voltage, permits a receiver to resolve the pulses of a received stream of asynchronously-occurring short duration pulses whose amplitude distribution among successive pulses varies over a large dynamic range.

Claims

1. An asynchronous pulse receiver for receiving and utilizing as a signal a stream of asynchronously-occurring pulses each consisting of a frequency burst of radiowave energy having a given relatively short duration, the distribution of amplitudes among successive pulses of said stream varying over a relatively large dynamic range;

said receiver comprising;

a. first means responsive to the receipt of said received stream for forwarding said pulses thereof as an output therefrom;

b. a broad-band, amplitude-limiting, gain-controlled radio-wave amplifier having said output of said first means applied as an input thereto, said radio-wave amplifier having a frequency passband sufficiently broad to substantially preserve said short duration of each of said received pulses of said stream passed therethrough, said radiowave amplifier limiting only in response to a received pulse of said stream having an amplitude in an upper portion of said dynamic range being passed therethrough, said radio-wave amplifier producing an output having an asynchronously-occurring pulse signal component and a noise component in response to said received stream of pulses being applied as a signal input thereto from said first means;

c. signal-utilization means which is responsive to said entire signal component of the output from said radio-wave amplifier;

d. noise-responsive means for deriving an AGC voltage having a magnitude in accordance with only the average intensity of noise applied as an input thereto, said AGC voltage being fed back to said radio-wave amplifier to control the gain of said radio-wave amplifier in accordance with the magnitude thereof, and e. second means for applying the output of said radio-wave amplifier as an input to said signal-utilization means and as an input to said noise-responsive means.

2. The receiver defined in claim 1, wherein said radio-wave amplifier is an IF amplifier and said first means includes the front-end circuits of said receiver.

3. The receiver defined in claim 1, wherein the intensity of said noise component is in part determined by the temperature at the input to said receiver, and wherein said second means includes temperature-compensation means for compensating for any effect on the gain of said radiowave amplifier due to said part of said noise component.

4. The receiver defined in claim 3, wherein said second means includes fourth means for directly coupling the output of said radio-wave amplifier to the input of said noise-responsive means, said output of said radio-wave amplifier being coupled to the input of said signal utilization means through said temperature-compensation means.

5. The receiver defined in claim 3, wherein said second means includes fourth means for coupling the output of said radio-wave amplifier to both the input of said noise-responsive means and the input of said signal-utilization means through said temperature compensation means.

6. The receiver defined in claim 1, wherein said passband of said radio-wave amplifier Includes a noise channel characterized by the substantial absence in said noise channel of any components of the frequency spectrum of pulses being amplified by said radio-wave amplifier, and wherein said noise-responsive means includes noise detection means turned only to said noise channel.

7. The receiver defined in claim 6, wherein substantially all components of the frequency spectrum of all pulses applied as an input to said radio-wave amplifier are within said passband thereof.

8. The receiver defined in claim 1, wherein said short duration is substantially one microsecond.

9. The receiver defined in claim 8, wherein said radio-wave amplifier has a passband width extending substantially from nine megacycles to thirty megacycles.

10. The receiver defined in claim 1, wherein said dynamic range is substantially forty-five decibels.

11. The receiver defined in claim 1, further including independent gain control means coupled to said radio-wave amplifier for further controlling the gain of said radio-wave amplifier in addition to and independent of said automatic gain control.

12. The receiver defined in claim 1, wherein said noise-responsive means includes detection means responsive to at least said noise component of the output of said radio-wave amplifier applied as an input thereto to derive a detected voltage, a low-frequency-limited amplifier, a comparator and reference level setting means for producing an output only in response to the input level thereto reaching a reference level, fourth means for applying said detected voltage as an input to both said low-frequency-limited amplifier and said comparator, an integrator having its input coupled to the output of said low-frequency-limited amplifier for integrating the output thereof, fifth means coupled to both said comparator and said low-frequency-limited amplifier for clamping the output of said low-frequency limited amplifier to a fixed return potential only in response to an output from said comparator, and sixth means for applying the output of said integrator as said automatic gain control voltage to said radio-wave amplifier.

13. The receiver defined in claim 12, wherein said reference level is set to produce an output from said comparator in response to said detected voltage indicating that said radio-wave amplifier is limiting, and wherein the value of said fixed return potential is equal to a nominal average noise level at the output of said low-frequency-limited amplifier.

14. The receiver defined in claim 12, wherein said sixth means includes seventh means for amplifying the output of said integrator and applying the output of said seventh means as said automatic gain control voltage to said radio-wave amplifier.