Electronic trigger for a radio frequency source

• US 4,250,454 A
• Filed: 03/26/1979
• Issued: 02/10/1981
• Est. Priority Date: 03/26/1979
• Status: Expired due to Term

• Current Assignee: ITT Corporation (ITT, Inc.)
• Original Assignee: International Telephone and Telegraph Corporation
• Inventors: Sakamoto, Norman Y.
• Primary Examiner(s): Heyman, John S.
• Application Number:
  US06/023,823
• Time in Patent Office: 687 Days
• Field of Search: 328/155, 328/71, 328/72, 328/73, 328/75, 328/55, 343/17.1 R, 331/1 A
• US Class Current: 327/241
• CPC Class Codes: G01R 25/08 by counting of standard pulses
• CPC Class Codes: G01S 7/282 Transmitters
• CPC Class Codes: H03L 7/0814 the phase shifting device being digitally controlled

Abstract

An electronic trigger circuit for an RF source, which electronic trigger may be advantageously used in a radar apparatus, for instance. The trigger employs digital logic devices including a register or counter, a circuit for initiating counting in the register in response to a received pretrigger signal and a circuit responsive to the occurrence of selected count in the register for enabling the RF source. A timing signal is generated, based upon the pretrigger signal in timed relationship to the time at which the RF source should nominally generate its RF signal. Typically, the RF source generates its RF signal at sometime after being enabled. A comparator circuit is provided for comparing the phase relationship of the aforementioned timing signal and the occurrence of the RF signal and is in turn coupled to an arithmetic circuit effective for altering the number of states through which the register counts. Preferably, the arithmetic circuit alters the number of states only when the comparison circuit indicates that the phase relationship differs by some preselected period of time. Thus, each time the RF source is fired, its output is compared with the time at which the output should nominally occur and when this difference exceeds a predetermined amount, the amount of delay between the time the pretrigger signal is received and the time the RF source is enabled is varied by changing the number of states through which the aforementioned register counts.

Claims

1. An electronic trigger controller for an RF source, said controller being responsive to a trigger signal and comprising:

a. a register;

b. means responsive to said trigger signal for enabling counting in said register in response thereto;

c. means responsive to a selected count in said register for enabling said RF source;

d. means for generating a timing signal in a timed relationship to the time which said RF source should nominally generate its RF signal;

e. means for comparing the phase relationship between the occurrence of said timing signal and the initiation of said RF signal; and

f. means responsive to said comparing means for altering the number of states through said register counts when enabled by said trigger.

2. An electronic trigger as defined in claim 1 wherein said altering means only alters the number of states through its said register counts when said comparing means determines that the phase relationship between the occurrence of said trigger signal and the initiation of said RF signal differs by a preselected amount.

3. An electronic trigger as defined in claims 1 or 2, further including a clock generator for generating a first clock of preselected period, a second clock having the same period as said first clock but having a different phase than said first clock and a third clock occurring as a multiple of the first clock, wherein said register counts in time with said third clock, wherein said trigger signal and timing signal occur essentially in time with said first clock, and wherein said altering means is operated essentially in time with said second clock.

4. An electronic trigger controller as defined in claim 1, wherein said altering means include a delay accumulator for storing a number, error latch and means for storing the number stored in said delay accumulator in said register, said error latch being set in one condition when said comparing means determines that said timing signal lags said RF signal and wherein said delay accumulator increments the number stored therein in response to said error latch being set in a selected one of its conditions and decrements the number stored therein in response to said error latch being set to the other one of its conditions.

5. An electronic trigger controller as defined in claim 1, wherein said means responsive to a selected count in said register is responsive to an overflow condition in said register and wherein said altering means includes a delay accumulator for storing a number, an error latch and means for storing the number stored in said delay accumulator in said register said error latch being set to a first condition when said comparing means determines that said timing signal leads said RF signal and being set to a second condition when said comparing means determines that said timing signal lags said RF signal, said delay accumulator in response to said error latch being set to said second condition.

6. An electronic trigger controller as defined in claim 1, wherein said means responsive to a selected count in said register is responsive to an overflow condition in said register and wherein said altering means includes a delay accumulator for storing a number, an error latch and means for storing the number stored in said delay accumulator in said register said error latch being set to a first condition when said comparing means determines that said timing signal leads said RF signal by a preselected amount, and being set to a second condition when said comparing means determines that said timing signal lags by said preselected amount, said delay accumulator being incremented response to said error latch being in said first condition and decremented in response to said error latch being in said second condition.

7. An electronic trigger controller according to claim 5 or 6, further including a clock generator for generating a first clock of preselected period, a second clock having the same period as said first clock but having a different phase than said first clock and a third clock occurring as a multiple of the first clock, wherein said register counts in time with said first clock, wherein said register counts in time with said third clock, wherein said trigger signal and timing signal occur essentially in time with said first clock, and wherein said altering means is operated essentially in time with said second clock.

8. An electronic trigger controller as defined in claim 7, wherein said second clock occurs in approximately a 180 degree relationship to said first clock and wherein said third clock has twice the frequency as said first clock.

9. A method of controlling an RF source to output RF energy at a preselected time in response to a pretriggering signal, said method comprising steps of:

a. storing a selected number in a counter;

b. initiating counting by said counter in response to the occurrence of said pretriggering signal;

c. modulating said RF source in response to said counter reaching a preselected count;

d. generating a timing signal in timed-relationship to the time at which the RF signal should nominally generate its RF energy;

e. comparing the time relationship between the occurrence of said timing signal and the generation of RF energy by said RF source; and

f. modifying said selected number based upon results of the comparing step.

10. The method according to claim 9, wherein said modifying step increments or decrements said selected number whenever the time relationship between the occurrence of the timing signal and the generation of RF energy by said RF source differs by a preselected period of time.

11. A method of controlling an RF source to output RF energy at preselected time in response to a pretriggering signal, said method comprising the steps of:

a. storing a selected number in a counter;

b. initiating counting in said counter in response to the occurrence of said pretriggering signal;

c. modulating said RF source in response to said counter reaching a selected count;

d. generating a timing signal in timed relationship to the time at which said RF source should nominally generate its RF energy;

e. comparing the time relationship between the occurrence of said timing signal and the generation of RF energy by said RF source; and

f. changing the number of states through which said counter will subsequently count based upon the results of said comparing step.

12. The method according to claim 11, wherein the changing step increments or decrements the number states through which the counter counts whenever the time relationship between the occurrence of said timing signal and the generation of RF energy by said RF source differs by a preselected amount.

13. The method according to claim 12 wherein the changing step increments said number whenever the timing signal leads the RF energy and decrements said number whenever the timing signal lags the RF energy.