Importance

Loading Importance Indicators...

Abstract

A local data unit (10) provides sequenced acquisition and transmission of data signals received in different signal formats from local and remotely deployed sensors (24, 28). The network uses a microprocessor based stage (42) to sequentially control acquisition of the data signals via an analog multiplexer (16) and conversion of those data signals into a binary format via either a voltage-to-frequency converter (48) and frequency digitizer (58) or, after normalization, directly via the frequency digitizer (58). Data transmission in a normal mode is achieved by using the binary data signals to toggle input reference signals applied to multiplexer (16) between low and high potentials, and applying those potentials to voltage to frequency converter (48) while a data transmitter (52) is held in an enabled conditon. The tone of the resulting frequency shift keyed signal is sensed by a carrier detector (82) which in turn enables a master telemetry receiver (80) to receive the data signals after conversion by a decoder (84). In a fallback mode activated upon failure of the processing unit, the multiplexer is sequentially addressed to apply the incoming data signals to the voltage-to-frequency converter (48) while the data transmitter (52) is held in an enabled condition. After detecting the occurrence of the partial failure, the master processing unit shifts to alternate binary conversion modes to accommodate the formats of the directly transmitted data signals in accordance with the scanning sequence of the fallback mode scanner (74).

Loading the Abstract Image...

First Claim