Pulse coherent transponder with precision frequency offset
US4006477A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 6, 1975 |
| Grant date | Feb 1, 1977 |
| Priority date | — |
| Expiry date | Jan 6, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/84
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A radar reply transponder for use with existing radar tracking systems wherein a reply pulse is generated and trasmitted in response to an associated interrogation pulse. The reply pulse is delayed in time and offset in frequency by a precise amount with respect to the interrogation pulse, but it is nevertheless phase coherent therewith so as to preserve the required Doppler frequency information and thereby permit accurate velocity measurements. Phase coherence is effectively maintained by utilizing a single continuously operating local oscillator for down-converting the received interrogation pulse to an intermediate frequency as well as up-converting the signal information to provide the delayed and frequency offset reply pulse. The precision frequency offset is obtained by switching in an additional reactance element in the oscillator-determining circuitry during the time up-converting is being effected. The radar transponder may thus be used in a high-vibration environment with no substantial introduction of error in velocity measurements caused by using two independent oscillators to formulate the frequency offset.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.