Transponder with reply frequency derived from frequency of received interrogation signal
US5355513A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 28, 1990 |
| Grant date | Oct 11, 1994 |
| Priority date | — |
| Expiry date | Dec 28, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/82
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A transponder includes a receiver for receiving a radio interrogation signal. The transponder also includes a phase locked loop decoder for deriving a reference signal from the received interrogation signal, and a radio transmitter for transmitting a transponder reply signal. The phase locked loop has an output which feeds the AC reference signal to the transmitter. The transmitter includes a frequency doubler which generates a transmitter radio frequency at double the frequency of the reference signal. The transmitter radio frequency is therefore controlled by the radio frequency of the interrogation signal. The phase locked loop includes a divide-by-N counter, where N is a predetermined integer parameter. The parameter N determines the derivation of the reference signal frequency from the interrogation signal frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.