Pulse sorting apparatus for frequency histogramming in a radar receiver system

• US 7,184,493 B1
• Filed: 10/15/2002
• Issued: 02/27/2007
• Est. Priority Date: 02/05/2002
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Alliant Techsystems Incorporated (Northrop Grumman Corporation)
• Inventors: Pringle, Richard Charles, Quan, Joanna S.
• Primary Examiner(s): Patel; Jay K.
• Assistant Examiner(s): Wang; Ted M.
• Application Number:
  US10/270,864
• Time in Patent Office: 1,596 Days
• Field of Search: 375/316, 375/275, 375/355, 342/111, 342/116, 342/18
• US Class Current: 375/316
• CPC Class Codes: G01S 7/021 Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals

Abstract

Disclosed is a real-time pulse sorting apparatus of a preprocessor in a pulsed radiation detection system. The apparatus, responsive to digital signals generated by a system receiver, uses the instantaneous frequency as the address input to store discrete data groups in main memory. Each data group, comprising the digital data corresponding to a single analog-to-digital converter sample point, includes the RF signal amplitude, inter-channel phase difference, instantaneous frequency as well as a unique pulse number generated by the pulse sorting apparatus. The present invention further includes a TOA memory for storing the time-of-arrival of each pulse at an address given by the pulse number. The main memory, organized in the form of a frequency-based histogram, together with the TOA memory, linked to the main memory by means of the pulse number pointer, sorts and records RF signal data with minimal processor control and intervention.

Claims

1. A pulse sorting apparatus of a preprocessor in a pulsed radiation detection system for acquiring a radio frequency (RF) signal, the radiation detection system including a central processing unit and a RF receiver for generating an instantaneous frequency measurement as well as RF signal data;

the apparatus comprising;

(a) a main memory for recording the RF signal data;

(b) addressing means, responsive to the receiver, for generating an available main memory address to store the RF signal data;

the available main memory address residing within one of two or more frequency bins where each frequency bin corresponds to a substantially unique RF signal bandwidth; and

(c) recording means, responsive to the receiver, for storing the RF signal data at the available main memory address of the main memory within a frequency bin corresponding to the instantaneous frequency measurement of the RF signal;

whereby the RF signal data are sorted in the main memory in the form of a frequency-based histogram.

2. The pulse sorting apparatus of claim 1 wherein the addressing means for generating an available main memory address to store RF signal data comprises a device for retrieving from one of a pair of random access memory (RAM) devices of a memory address of a most recent prior data group stored within said instantaneous frequency bin.

3. The pulse sorting apparatus of claim 1 wherein the recording means comprises a gating signal, latches for the recordation of digital measures of signal amplitude, inter-channel phase difference and receiver temperature and, respective first-in-first-out devices (FIFOs) enabled by said gating signal;

said gating signal being an enabling signal based on qualifying detected RF signals.

4. The pulse sorting apparatus of claim 3 wherein the apparatus further includes pulse counting means for generating a RF pulse number;

said RF pulse number sequentially storable with the RF signal data by the recording means in the main memory.

5. The pulse sorting apparatus of claim 4 wherein the pulse counting means for generating RF pulse number is an incremental add and hold counter.

6. The pulse sorting apparatus of claim 4 wherein the apparatus further includes a time-of-arrival memory that stores a RF signal time-of-arrival at an address location given by the RF pulse number, whereby the RF pulse number in main memory serves as a pointer to the RF signal time-of-arrival in the time-of-arrival memory.

7. The pulse sorting apparatus of claim 3 wherein the apparatus further includes a last address memory for storing two or more previous main memory addresses;

one previous main memory address for each of the frequency bins.

8. The pulse sorting apparatus of claim 7 wherein the main memory comprises two banks of memory devices;

the two banks being alternately written to by the pulse-sorting apparatus and read from by the central processing unit at each radar interrupt cycle.

9. The pulse sorting apparatus of claim 7 wherein the addressing means for generating an available main memory address to store RF signal data further comprises a device for incrementing the last address.

10. A pulse sorting apparatus of a preprocessor in a pulsed radiation detection system for acquiring a radio frequency (RF) signal, the radiation detection system including a central processing unit and a digital receiver for generating an instantaneous frequency measurement as well as RF signal data;

the apparatus comprising;

(a) pulse counting means, responsive to the digital receiver, for generating a unique RF pulse number for each RF signal received;

(b) time of arrival (TOA) memory means, responsive to the pulse counting means, for recording RF signal TOA;

the RF signal TOA being stored in the TOA memory means at an address location given by the RF pulse number; and

(c) a main memory, responsive to the digital receiver and the pulse counting means, for recording the RF pulse number and RF signal data;

the RF signal data comprising one or more RF signal amplitude and phase measurements;

the RF signal data being recorded at a main memory address of the main memory means in one of a plurality of frequency bins where each frequency bin corresponds to a unique RF signal bandwidth;

the RF signal data being recorded in the frequency bin corresponding to the instantaneous frequency measurement of the RF signal;

whereby the RF signal data are sorted in the main memory in the form of a frequency-based histogram.

11. The pulse sorting apparatus of claim 10 wherein the pulse counting means for generating RF pulse number is an incremental add and hold counter.

12. The pulse sorting apparatus of claim 10 wherein the TOA memory means for recording the RF signal TOA comprises one or more memory devices whereby the RF signal TOA of a leading edge of a pulse, the pulse having a pulse number, and the RF signal TOA of a trailing edge of the pulse is storable, each in association with the pulse number.

13. The pulse sorting apparatus of claim 10 wherein the TOA memory means for recording the RF signal TOA comprises one or more memory devices whereby the RF signal TOA of a trailing edge of a pulse, the pulse having a pulse number, is storable in association with the pulse number.

14. The pulse sorting apparatus of claim 10 wherein the TOA memory means for recording the RF signal TOA comprises one or more memory devices whereby the RF signal TOA of a leading edge of a pulse, the pulse having a pulse number, is storable in association with the pulse number.

15. The pulse sorting apparatus of claim 10 wherein the RF signal data of each frequency bin of the main memory is consecutively stored.

16. The pulse sorting apparatus of claim 15 wherein the apparatus further includes a last address means, the last address means comprising:

(a) a last address memory for recording last main memory address used to record RF signal data within each frequency bin of the main memory; and

(b) incrementing means for incrementing the last main memory address used to generate a new main memory address at which current RF signal data are stored in main memory.

17. The pulse-sorting apparatus of claim 16 wherein the incrementing means for incrementing the last main memory address used to generate a new main memory address at which current RF signal data are stored in main memory is an addressing function that increments the last address iteratively until a next data group is located.

18. The pulse-sorting apparatus of claim 16 wherein the apparatus further comprises latching means, responsive to the pulse counting means and digital receiver, for latching the RF pulse number, RF signal data and instantaneous frequency measurement and thereby making the pulse number, signal data and frequency measurement available to the main memory.

19. The pulse sorting apparatus of claim 18 wherein the latching means comprises one or more shift registers and corresponding first-in-first-out (FIFO) memory operatively coupled to the main memory.

20. The pulse-sorting apparatus of claim 19 wherein the apparatus further includes RF signal detection means for qualifying the RF signal received.

21. The pulse-sorting apparatus of claim 20 wherein the FIFO memory receives a write enable signal by way of the RF signal detection means;

the FIFO memory being write enabled in such a way as to store a RF signal leading edge.

22. The pulse-sorting apparatus of claim 21 wherein the main memory comprises two banks of memory devices;

the two banks alternately, with each radar interrupt cycle, writable by the pulse sorting apparatus and readable from the central processing unit.

23. A pulse-sorting apparatus comprising:

(a) a signal detector, wherein the signal detector qualifies a plurality of incoming RF signals from a digital receiver;

(b) a pulse counter, operatively coupled to the signal detector, wherein the pulse counter generates a unique RF pulse number for each RF signal;

(c) a time-of-arrival (TOA) counter, operatively coupled to the signal detector, wherein the TOA counter outputs an RF signal TOA upon qualification of an RF signal;

(d) a TOA memory element having an address input and a data input, the address input operatively coupled to the pulse counter and data input operatively coupled to the TOA counter, whereby the RF signal TOA is stored at an address location given by the RF pulse number;

(e) a latch, responsive to the digital receiver and pulse counter, wherein the latch latches RF signal data, of the RF signal, the RF pulse number and an instantaneous frequency measurement provided by the digital receiver;

(f) a memory addressing element, operatively coupled to the digital receiver, wherein the digital receiver generates a main memory address for storing the RF signal data and the RF pulse number;

the main memory address residing within a frequency bin corresponding to the instantaneous frequency measurement;

the frequency bin being one of two or more frequency bins where each frequency bin corresponds to a unique RF signal bandwidth; and

(g) a main memory recorder, wherein the main memory recorder records the RF signal data, instantaneous frequency measurement and RF pulse number at the main memory address;

the main memory including an address input and a data input;

the data input operatively coupled to the latch and pulse counter;

the address input operatively coupled to the latch and the memory addressing element;

whereby the central processing unit retrieves pre-sorted RF signal data from the main memory and RF signal TOA from the TOA memory.