Aircraft traffic alert and collision avoidance device

• US 5,388,047 A
• Filed: 03/18/1992
• Issued: 02/07/1995
• Est. Priority Date: 01/09/1990
• Status: Expired due to Fees

• Current Assignee: Ryan International Corp. (Avidyne Corporation)
• Original Assignee: Ryan International Corp. (Avidyne Corporation)
• Inventors: Brodegard, William C., Ryan, Dean E., Ryan, Paul A.
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): LOUIS JACQUES, JACQUES H
• Application Number:
  US07/853,147
• Time in Patent Office: 1,056 Days
• Field of Search: 364/461, 364/516, 364/554, 364/439, 364/443, 364/460, 364/424.06, 364/452, 342/455, 342/30, 342/29, 342/31, 342/32, 340/961, 340/967, 340/968, 340/974, 340/975
• US Class Current: 701/301
• CPC Class Codes: G01S 13/74 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
• CPC Class Codes: G01S 13/767 Responders; Transponders teaching or practice apparatus for gun-aiming or gun-laying using reflecting targets or active targets F41G3/26
• CPC Class Codes: G01S 13/933 of aircraft or spacecraft

Abstract

A proximity warning device for aircraft responds solely to transmissions from transponders. The host aircraft has a host transponder and a signal is generated therein and coupled to the device to indicate transmission of a host reply. Selective suppression is implemented based on presence of an SSR beam which is indicated by the signal. Suppression pulses have a fixed duration but randomly selected intervening durations. Data collection proceeds without regard for suppression or the presence of host replies. The shaping of data collection intervals free of interference from suppression provides for improved efficiency for later data decoding and processing. The signal is used to specially mark collected data generated by a host reply. The ability to discriminate between host and other replies allows completely new performance monitoring functions. In one case, the health of the receiver is deduced from the amplitude of host replies. In another case the effectiveness of suppression is noted by capturing host replies in the presence of a suppression pulse.

Claims

1. Apparatus for proximity alerting an operator of a transponder equipped host aircraft to the presence of other aircraft based on receipt of replies of aircraft carried transponders to interrogation by an SSR comprising:

a) a receiver tuned to receive transponder replies;

b) a processor coupled to said receiver for decoding received replies and processing information extracted therefrom for operator alerting;

c) means coupling a signal from said host transponder to said processor to indicate transmission of a reply by said host transponder; and

d) means in said processor responsive to said signal for initiating generation of a suppression signal pulse train.

2. Apparatus as recited in claim 1 further including:

e) timer means in said processor responsive to said signal for timing a predetermined period following said signal; and

f) means included in said processor and responsive to expiration of said predetermined period for terminating generation of said suppression signal pulse train.

3. Apparatus as recited in claim 2 wherein said means responsive to expiration of said predetermined period resets said timer means on each said signal whereby said timer means expires only after expiration of said predetermined period in the absence of said signal.

4. Apparatus as recited in claim 1 wherein said means for initiating a suppression signal pulse train comprises:

d1) means for creating a suppression pulse of a predetermined duration;

d2) means responsive to termination of a suppression pulse for selecting a random delay; and

d3) means responsive to termination of said random delay for creating a further suppression pulse of said predetermined duration.

5. Apparatus as recited in claim 4 wherein each of suppression pulses has a duration of approximately 35 μ

s.

6. Apparatus as recited in claim 4 wherein said random delay is selected as lying in a range of about 190 μ

s to about 860 μ

s with a mean duration of about 525 μ

s.

7. A method of passively collecting, in a transponder equipped host aircraft, information on proximity of other aircraft based on receipt of transponder replies from other aircraft comprising the steps of:

a) providing a receiver responsive to transmissions of aircraft transponders;

b) providing a processor coupled to said receiver for decoding and processing replies received by said receiver from aircraft transponders;

c) coupling an output from said host transponder to said processor; and

d) initiating suppression of said transponder in response to detection, by said processor of the output from said host transponder coupled to said processor.

8. A method as recited in claim 7 including the further step of:

e) initiating a timer, for timing out a predetermined period, on detection of said output from said host transponder, resetting said timer on detection of the output from said host transponder during a timing operation of said timer; and

f) terminating suppression to said transponder in the event said timer completes timing out said predetermined period.

9. A method as recited in claim 7 wherein said step of initiating suppression of said transponder includes the further steps of:

d1) creating a suppression pulse of a predetermined duration;

d2) selecting, in response to termination of a suppression pulse, a random delay; and

d3) in response to expiration of said selected random delay, creating a further suppression pulse of said predetermined duration.

10. A method as recited in claim 9 wherein said predetermined duration is about 35 μ

s.

11. A method as recited in claim 9 said random delay is selected as lying in a range of about 190 μ

s to about 860 μ

s with a mean duration of about 525 μ

s.

12. A method of suppressing a host transponder to enable detection, by a host carried proximity warning device of other aircraft where said host carried proximity warning device is based on detection of replies by transponders of other aircraft comprising the steps of:

a) detecting replies from said host transponder;

b) initiating, in response to detection of a reply by said host transponder, alternating periods of listening/suppression and periods of listening/no suppression by timed suppression of said host transponder; and

c) terminating said alternating periods by terminating said timed suppression to said host transponder in the absence of a reply from said host carried transponder for a predetermined period.

13. A method as recited in claim 12 wherein said step a) comprises:

a1) providing a host borne receiver tuned to transponder transmissions;

a2) providing a host borne processor responsive to outputs of said host borne receiver; and

a3) providing an electrical connection between said host borne processor and said host transponder to enable said host borne processor to differentiate replies transmitted by said host transponder from replies transmitted by other transponders.

14. A method as recited in claim 12 wherein said step of initiating alternating periods of listening/suppression with periods of listening/no suppression comprises:

b1) in response to detection of a host transponder reply, initiating a suppression sequence including suppression pulses of a predetermined duration separated by random delays selected within a given range of delays; and

b2) maintaining a listen cycle for the collection of data and transfer of collected data substantially independent of the suppression sequence.

15. A method as recited in claim 14 wherein said predetermined duration is about 35 μ

s and said random delay lies within a range of about 190 μ

s to about 860 μ

s with a mean of about 525 μ

s.

16. Apparatus for proximity alerting an operator of a transponder equipped host aircraft to the presence of other aircraft based on receipt of replies of aircraft carried transponders to interrogation by an SSR comprising:

a) a receiver tuned to receive transponder replies for generating receiver data representing transponder replies;

b) a processor responsive to said receiver data for storing said receiver data, for decoding received replies and processing information extracted therefrom for operator alerting;

c) means coupling a signal from said host transponder to said processor to indicate transmission of a reply by said host transponder; and

d) means responsive to said signal and to concurrent receiver data for uniquely encoding said concurrent receiver data to represent a host transponder reply.

17. Apparatus as recited in claim 16 which further includes:

e) threshold means responsive to said receiver data for indicating whether said receiver data indicates an amplitude below a predetermined threshold; and

f) alarm means jointly responsive to said signal and to an indication from said threshold means indicating an amplitude below said predetermined threshold for indicating a receiver failure.

18. Apparatus as recited in claim 17 wherein said threshold means comprises an analog to digital converter with a particular output and wherein said alarm means includes a gate responsive to said signal and to said particular output for clearing a latch in the presence of said signal and in the absence of an output from said particular output of said analog to digital converter.

19. A method of proximity alerting an operator of a transponder equipped host aircraft to the presence of other aircraft based on receipt of replies of aircraft carried transponders to interrogations by an SSR, said method comprising:

a) generating data from said receiver representing transponder replies received by said receiver;

b) storing said data for processing to identify aircraft proximate to said host aircraft;

c) generating a signal, simultaneous with a host transponder reply;

d) uniquely encoding data from said receiver in the presence of said signal; and

e) storing said uniquely encoded data to discriminate host transponder replies from other replies.

20. A method as recited in claim 19 comprising the further steps of:

f) generating a suppression pulse for suppression of said host transponder; and

g) providing a distinctive indication on receipt of said signal during a duration of said suppression pulse.

21. A method as recited in claim 19 comprising the further steps of:

f) comparing amplitude of data from said receiver concurrent with said signal to a predetermined threshold; and

g) indicating a receiver failure if said amplitude of receiver data concurrent with said signal is less than a predetermined threshold.

22. In an apparatus for alerting an operator of a transponder equipped host aircraft to the presence of other aircraft based on receipt of replies of aircraft carried transponders to interrogation by an SSR, a performance monitor for monitoring operation of the alerting apparatus, the alerting apparatus comprising a receiver tuned to receive replies transmitted by aircraft transponders and a processor responsive to said receiver, said performance monitor comprising:

a) means coupling a signal indicating transmission of a reply by said host transponder from said host transponder to said processor;

b) means for indicating amplitude of a reply from said receiver;

c) means for comparing said indicated amplitude of a reply, concurrent with said signal, to a threshold; and

d) means responsive to said indicated amplitude less than said threshold for indicating a receiver failure.

23. An apparatus for alerting an operator of a transponder equipped host aircraft to the presence of other aircraft based on receipt of replies of aircraft carried transponders to interrogation by an SSR, said apparatus comprising:

a) a receiver tuned to receive replies transmitted by aircraft transponders;

b) a processor responsive to said receiver; and

c) a performance monitor comprising;

c1) means coupling a signal from said host transponder indicating transmission of a reply by said host transponder, to said processor;

c2) means for indicating amplitude of a reply from said receiver;

c3) means for comparing said indicated amplitude, concurrent with said signal, to a threshold; and

c4) means responsive to said indicated amplitude less than said threshold for indicating a receiver failure.

24. Apparatus as recited in claim 23 wherein said means for indicating a receiver failure comprises:

c41) a counter;

c42) first means for changing the contents of the counter in one sense in response to indications of amplitude less than said threshold;

c43) second means for changing the contents of the counter in an opposite sense in response to indications of amplitude greater than said threshold; and

c44) means responsive to a counter in said counter having a predetermined relation to a specified count for alerting an operator to a receiver failure.

25. Apparatus as recited in claim 24 which further includes means responsive to a count in the counter which does not have the predetermined relation to the specified count for cancelling any alert of receiver failure.

26. Apparatus as recited in claim 24 wherein said first means increments the counter, but only up to a first predetermined count and wherein said second means decrements the counter, but only down to a second predetermined count.

27. In an apparatus for alerting an operator of a transponder equipped host aircraft to the presence of other aircraft based on receipt of replies of aircraft carried transponders to interrogation by an SSR, a performance monitor for monitoring operation of the alerting apparatus, the alerting apparatus comprising a receiver tuned to receive replies transmitted by aircraft transponders, a processor responsive to said receiver including a suppression generator for generating a signal to suppress transmissions from said host transponder and an electrical connection between said host transponder and said processor for a signal indicating transmission of a reply from said host transponder, said performance monitor comprising:

a) monitoring means initiated into operation during suppression of said host transponder for monitoring for the presence of said signal from said host transponder indicating transmission of a reply by the host transponder; and

b) means responsive to said monitoring means for indicating a suppression failure in the event said monitoring means detects the presence of said signal from said host transponder indicating transmission of a reply by the host transponder.

28. Apparatus as recited in claim 27 wherein said means for indicating a suppression failure comprises:

d21) a counter;

d22) first means for changing the contents of the counter in one sense in response to detection of the signal from the host transponder;

d23) second means for changing the contents of the counter in an opposite sense in response to failure to detect the signal from the host transponder; and

d24) means responsive to a count in said counter having a predetermined relation to a specified count for alerting an operator to a suppression failure.

29. Apparatus as recited in claim 28 which further includes means responsive to a count in the counter which does not have the predetermined relation to the specified count for cancelling any alert of suppression failure.

30. Apparatus as recited in claim 29 wherein said first means increments the counter, but only up to a first predetermined count and wherein said second means decrements the counter, but only down to a second predetermined count.

31. An apparatus for alerting an operator of a transponder equipped host aircraft to the presence of other aircraft based on receipt of replies of aircraft carried transponders to interrogation by an SSR;

a) a receiver tuned to receive replies transmitted by aircraft transponders;

b) a processor responsive to said receiver including a suppression generator for generating a signal to suppress transmissions from said host transponder;

c) an electrical connection between said host transponder and said processor for a signal from said host transponder indicating transmission of a reply from said host transponder;

d) a performance monitor comprising;

d1) monitoring means initiated into operation during suppression of said host transponder for monitoring for the presence of said signal from said host transponder indicating transmission of a reply by the host transponder; and

d2) alarm means responsive to said monitoring means for indicating an interface failure in the event said monitoring means detects the presence of said signal from said host transponder indicating transmission of a reply by the host transponder.

32. A method of monitoring operation of an apparatus for alerting an operator of a host aircraft, with its own host transponder, to proximity of other aircraft based on detection of replies, transmitted by aircraft carried transponders, to interrogations by an SSR, comprising the steps of:

a) receiving and digitizing replies from transponders to SSR interrogations;

b) indicating those of the replies which originated from the host transponder;

c) comparing a digitized reply which is indicated as originated from the host transponder to a threshold; and

d) indicating a receiver failure in the event the digitized reply operated on in step (c) is found to be less than said threshold.

33. A method of monitoring operation of an apparatus for alerting an operator of a host aircraft, with its own host transponder, to the proximity of other aircraft based on detection of replies, transmitted by aircraft carried transponders, to interrogation by an SSR, comprising the steps of:

a) receiving and recording replies from transponders to SSR interrogations, said recording including recording an indication of the amplitude of the reply;

b) detecting replies which originated from the host transponder;

c) selectively suppressing the host transponder;

d) detecting the simultaneous occurrence of transponder suppression and receipt of a transponder reply from the host transponder; and

e) indicating a suppression failure in the event the detecting step d) indicates the simultaneous occurrence of transponder suppression and receipt of a transponder reply from the host transponder.

34. Apparatus for proximity alerting an operator of a transponder equipped host aircraft to the presence of other aircraft based on receipt of replies of aircraft carried transponders to interrogation by an SSR, where a transponder reply has a duration no less than a predetermined period, said apparatus comprising:

a) a receiver tuned to receive transponder replies;

b) processor means coupled to said receiver for decoding received replies and processing information extracted therefrom for operator alerting;

c) said processor means including;

c1) an analog to digital converter responsive to an output of said receiver;

c2) a memory selectively responsive to an output of said analog to digital converter;

c3) detecting means responsive to an output of said analog to digital converter for detecting a predetermined period containing no significant output from said receiver;

c4) enabling means responsive to said detecting means for thereafter enabling said high speed memory to respond to said output of said analog to digital converter by recording said output;

whereby operation is improved by preventing memory response to trailing portions of transponder replies.

35. Apparatus as recited in claim 34 wherein said processor means further comprises:

c5) timing means initiated into operation by said detecting means for timing a first period;

c6) data detecting means responsive to said output of said analog to digital converter for detecting the presence or absence of significant output during operation of said timing means; and

c7) control means responsive to said data detecting means detecting the absence of significant output during said first period of said timing means for re-initiating said timing means.

36. Apparatus as recited in claim 35 wherein said control means responds to said data detecting means detecting the presence of significant output during said first period of said timing means for initiating a second control means into operation, said processor means further including:

c8) said second control means for monitoring during time succeeding the first period;

if said succeeding time contains no significant output from said receiver, said second control means terminates responsiveness of said memory to said analog to digital converter and initiates decoding of data recorded in said memory;

if said succeeding predetermined period does contain significant output from said receiver then said control means terminates responsiveness of said memory to said analog to digital converter and initiates decoding of data recorded in said memory either on;

detection of said a further predetermined period with no significant output from said receiver;

or

on expiration of a second fixed period measured from initiation of said first fixed period.

37. Apparatus as recited in claim 36 wherein said predetermined period is on the order of 21 μ

s, said first period is on the order of 100 μ

s and the second fixed period is on the order of 300 μ

s.

38. A method of passively collecting, in a transponder equipped host aircraft, information on proximity of other aircraft based on receipt of transponder replies from other aircraft, wherein the transponder replies extend over at least a predetermined period in time, said method comprising the steps of:

a) providing a receiver responsive to transmissions of aircraft transponders;

b) providing a memory coupled to said receiver for selectively recording data from said receiver;

c) providing a processor coupled to said memory for identifying replies within said recorded data, decoding identified replies and processing decoded replies for identification of proximity information; and

d) inhibiting said memory from responding to receiver output for an initial predetermined period of no significant receiver output whereby said memory operation is improved by preventing recording of trailing portions of transponder replies.

39. A method as recited in claim 38 which includes the further steps of:

e) enabling said memory to record data from said receiver following said predetermined period of no significant receiver output for at least a first fixed period;

f) initiating a timer at the expiration of said first fixed period for detecting either;

a predetermined period of no significant receiver output;

or

expiration of a second fixed period measured from initiation of said first fixed period; and

g) terminating responsiveness of said memory to said receiver output and initiating decoding of data recorded in said high speed memory.

40. A method as recited in claim 39 wherein said predetermined period is on the order of 21 μ

s, said first fixed period is on the order of 100 μ

s and the second fixed period is on the order of 300 μ

s.