| 摘要 |
A low power density radio system is achieved using a simple FSK transmitter arranged to transmit very short bursts to a receiver at frequent intervals. Such a system can be used between a meter transponder and a reader in an AMR system to eliminate the need for a receiver in the transponder and still achieve extended battery life. The problems of detecting and demodulating the short burst may be overcome by the use of a sample and hold circuit that detects a preamble of reversals (20) to indicate the presence of the burst (22, 24) and to provide the reference value to correct for the DC pedestal voltage (26) that arises as a function of the transmitter and receiver frequency errors.
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