Coded coherent transponder

• US 4,218,680 A
• Filed: 01/12/1979
• Issued: 08/19/1980
• Est. Priority Date: 01/12/1979
• Status: Expired due to Term

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Kennedy, Peter D.
• Primary Examiner(s): Tubbesing, T. H.
• Application Number:
  US06/002,821
• Time in Patent Office: 585 Days
• Field of Search: 343/6.8 R, 343/6.8 LC
• US Class Current: 342/51
• 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

Abstract

A transponder including a receiver and transmitter for receiving an interrogation signal and transmitting a coherent response with circuitry for modulating the coherent response to include a predetermined coded complex phase and/or amplitude shift therein to convey information, such as the identity of the transponder.

Claims

1. A coded coherent transponder with a receiver and a transmitter for receiving an interrogation signal and transmitting a coherent response including predetermined coded information, said transponder including means for introducing a predetermined coded complex phase shift into the coherent response representative of a simultaneous plurality of Doppler frequency components.

2. A coded coherent transponder as claimed in claim 1 wherein the transponder further includes means for introducing a predetermined amplitude shift into the coherent response.

3. A coded coherent transponder with a receiver and a transmitter for receiving an interrogation signal and transmitting a coherent response including predetermined coded information, said transponder including means for introducing a predetermined coded amplitude shift into the coherent response representative of a simultaneous plurality of Doppler frequency components.

4. A coded coherent transponder comprising:

(a) a receiver for receiving an interrogation signal from a remotely positioned, pulsed radar;

(b) delay means coupled to said receiver for delaying the interrogation signal;

(c) phase shifting means coupled to said delay means for introducing a predetermined coded complex phase shift into the interrogation signal representative of a simultaneous plurality of Doppler frequency components; and

(d) a transmitter coupled to receive the delayed and phase shift coded signal for transmitting a coherent coded response to the remotely positioned, pulsed radar, said delay means introducing sufficient delay to allow the reception of a substantially complete interrogation signal prior to transmission of the response.

5. A coded coherent transponder as claimed in claim 4 wherein the phase shifting means includes circuitry for dividing the interrogation signal into in-phase and quadrature components, first and second attenuators coupled to operate on the in-phase and quadrature components, respectively, in response to a code applied thereto, and circuitry for recombining the components into a resultant, phase shift coded signal.

6. A coded coherent transponder as claimed in claim 5 wherein each of the first and second attenuators includes a double-balanced diode mixer.

7. In a coherent transponder including a receiver and a transmitter for receiving an interrogation signal and transmitting a coherent response, a method of coding the response to represent predetermined data, said method comprising the steps of:

(a) receiving the interrogation signal;

(b) phase modulating the receiver signal in accordance with a predetermined code by introducing a predetermined complex phase shift into the signal to represent a plurality of simultaneous predetermined responses; and

(c) transmitting the modulated signal.