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Abstract

An interface device interacts between a digital data terminal and a frequency modulated analog transceiver module to control data flow between the digital data terminal and the transceiver module and to adapt the transceiver module to transmit digital data signals and to communicate messages containing digital signals to the digital data terminal. The interface circuit includes a digitally implemented signal shaping circuit which samples an analog quiescent state bias signal level of a voltage controlled oscillator circuit of the transceiver module. The signal shaping circuit samples and converts the sampled quiescent bias signal level to an equivalent digital data value. The digital equivalent value is increased by and decreased by a predetermined deviation value, thereby generating equivalent values of high and low modulation bias voltage levels. The interface device includes a programmable memory for storing a number of reference values which allow the interface device to be configured to normalize data signals and control sequences in accordance with operating characteristics of any one of a number of available transceiver modules. The stored reference values control timing sequences for initiating and shutting down a transmit cycle, for storing predetermined maximum deviation values for the modulation bias signal of transmitted data messages, and for demodulating received signals.

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First Claim