User Guide

PAMS
Technical Documentation
NHD–4
System Overview
Page 3–16
Original 11/97
An Audio Analyzer is used to determine the phones SINAD response. Minimum
receiver sensitivity is defined as the RF level (–116 dBm) that, when modulated in a
specified manner (8 kHz deviation with a 1 kHz tone) will result in a SINAD of at
least 12 dB. SINAD is an acronym for Signal, Noise and Distortion, not just the
signal to noise ratio.
The frequency scheme illustrated mixes the UHF VCO with the 90 MHz VHF VCO
and uses the difference frequency to arrive at the final transmit frequency. Transmit
voice is digitialized by the CODEC. This data is processed by the DSP then sent to
the CDSB for further processing. The analog data stream is converted to an analog
signal in the CDRFI. This analog data signal then frequency modulates the 180
MHz VHF VCO.