Correlator and control system for vehicular collision avoidance

• US 3,887,916 A
• Filed: 04/30/1973
• Issued: 06/03/1975
• Est. Priority Date: 06/27/1972
• Status: Expired due to Term

• Current Assignee: Ronald Bruce Goyer
• Original Assignee: Ronald Bruce Goyer
• Inventors: Goyer, Ronald Bruce
• Primary Examiner(s): Hubler, Malcolm F.
• Application Number:
  US05/355,448
• Time in Patent Office: 764 Days
• Field of Search: 343/6.5R,6.5LC
• US Class Current: 342/30
• CPC Class Codes: G01S 13/79 Systems using random coded signals or random pulse repetition frequencies , e.g. "Separation and Control of Aircraft using Non synchronous Techniques" [SECANT]
• CPC Class Codes: G01S 13/933 of aircraft or spacecraft
• CPC Class Codes: G06F 17/15 Correlation function computation including computation of convolution operations arithmetic circuits for sum of products per se, e.g. multiply-accumulators G06F7/5443; digital filters, e.g. FIR, IIR, adaptive filters H03H17/00

Abstract

A system for controlling the transmission of randomly asynchronous probe signals and '"'"''"'"''"'"''"'"'defruiting'"'"''"'"''"'"''"'"' received reply signals from remote aircraft through code division multiplex using both a random coded frequency hopping signal and a random coded repetition rate or PFR. The reply signals are correlated and accumulated by a logic circuit such that only replies of an aircraft within a predetermined range will be designated by an appropriate control signal.

Claims

1. A digital correlator comprising:

a. a source of random digital signals of varying pulse width, b. means for periodically sampling said random signals to generate any one of two interrogation signals each having a distinguishing indicia from the other, b1. said interrogation signals adapted for transmission to the environment once each period for interrogating the presence of remote stations, b2. said remote stations having means responsive to said interrogation signals to generate and transmit to the environment a reply signal corresponding to the respective interrogation signals received by them, b3. said remote stations further having means for periodically transmitting any one of two interrogation signals, corresponding to said first mentioned interrogation signals, generated in response to a random source different from said first mentioned random source, c. means for receiving signals comprising said reply signals and interrogation signals from said remote stations, d. means for discriminating said received signals into signals corresponding to either one of said tWo interrogation signals, e. digital circuit means in synchronism with said periodic sampling means for comparing the transmitted and replied interrogation signals during each sampling period for providing any one of said two signals corresponding, respectively, to like and unlike correlations of the sampled and received signals, and f. digital circuit means responsive to said comparison means for integrating the like and unlike signals.

2. A correlator according to claim 1 wherein said integrating means includes means for sequentially integrating the signals from said comparison means according to the range to said remote stations.

3. A correlator according to claim 2 wherein said integrating means includes means for limiting the integration of like signals to a predetermined value manifesting the presence of a remote station in the environment.

4. A correlator according to claim 3 wherein said limiting means includes a logical comparator circuit having a preset logical number adapted to detect the integration of like signals greater than said preset logical number.

5. A correlator according to claim 4 wherein said comparator circuit includes means for generating a hold signal for locking said integrating means to the preset number when said integrator accumulates like signals corresponding to said preset number.

6. A correlator according to claim 1 including means for jittering said transmitted signals to shift in time the transmitted signal relative to a given period.

7. A correlator according to claim 6 wherein said jittering means includes:

a. means for sampling a plurality of said random signals, b. a counter including means for preloading a count into said counter defining a starting count, c. means for counting said plurality of sampled random signals by said counter so that a predetermined decoded end count occurs in a random time interval from the preloaded start count, d. means for generating a pulse in response to said counter counting to a predetermined number of said plurality of sampled random signals, said pulse defining the periodic rate of comparing the transmitted and received signals.

8. A correlator according to claim 1 including means for providing a tracking signal to tracking means of a remote station identified by said correlator.

9. A digital correlator comprising:

a. a source of random signals of substantially constant amplitude and randomly varying duration, b. means responsive to said signals for generating an interrogation signal for transmission on a random time basis to the environment for interrogating the presence of remote stations seeking thereby reply signals from said remote stations, b1. said interrogation signal generating means including means for shifting in time the transmission of said interrogation signal relative to a given period according to the variation of the duration of said source signals, c. said remote stations having means responsive to said interrogation signals to generate and transmit to the environment a reply signal corresponding to said interrogation signal received by said remote station, and having further means for generating and transmitting interrogation signals corresponding to said first mentioned interrogation signals, d. means for receiving reply signals and interrogation signals from remote stations, e. means for discriminating said received reply signals from received interrogation signals, f. digital circuit means in synchronism with said signal source of random signals for comparing during a given time period transmitted interrogation signals and received reply signals, and g. means for identifying the range of remote stations by the correlation of said received reply signals.