SIGNAL SELECT IN UNDERGROUND LINE LOCATION

摘要

A transmitter and receiver for performing a signal select algorithm are provided. A transmitter for providing a signal on a line to be located includes at least one direct digital synthesizer, the direct digital synthesizer producing two component frequencies in response to an input square wave signal; and a feedback loop providing the input square wave.

主权项

1. A receiver, comprising
an antenna provides an antenna signal based on a detected signal; an analog filter that filters the antenna signal to generate a filtered signal; an amplifier that amplifiers the filtered signal to generate an amplified signal; a CODEC that receives the amplified signal and provides a decoded signal; and a digital signal processor that analyzes the decoded signal to receive a signal select signal that includes two frequencies, the digital signal processor including
a demodulator to demodulate and downsample the decoded signal to receive an in-phase component and a quadrature component; anda calculation that provides an intensity and a phase of a signal formed from the in-phase component and the quadrature component;wherein the phase of the signal formed from the in-phase component and the quadrature component corresponds to a phase reference of a transmitted frequency shift keyed (FSK) signal.