Watkins Johnson WJ-8711A Technical Data Manual - page 5
5
WJ-8711A
based on operator selection of the receiver’s
parameters:
●
Noise blanking
●
Fine tuning to 1-Hz resolution
●
IF filtering
●
Gain control (AGC Fast, AGC Medium, AGC
Slow, or Manual)
●
Signal strength and squelch functions
●
Signal demodulation and BFO
●
Generation of a multiplexed digital data stream
containing 1 or 2 demodulated audio channels and
a post-filtered IF signal
The IF/audio output subsystem performs the analog
reconstruction of the IF and audio signals provided by
the DSP subsystem in digital form. The analog audio
signals are routed through two distinct signal paths to
accommodate ISB detection mode. In all other
detection modes, both paths contain identical audio
signals. These two audio paths are processed to
provide a 2-channel headphone output, two balanced
600-ohm line audio outputs and an 8-ohm speaker
output containing one or both audio channels in ISB
mode. After analog reconstruction, the IF signal is
upconverted to 455 kHz, passed through a bandpass
roofing filter to remove mixer products, buffered and
routed to the rear panel IF output connector.
The microprocessor-based control subsystem per-
forms the receiver’s internal control, acts as an
interface with the front panel, and provides a remote
control function through either the RS-232 or the
optional RS-485, RS-422, or IEEE-488 interfaces.
The control subsystem also monitors hardware status
within the receiver and, when commanded, performs a
built-in test sequence that isolates circuit faults to the
module level.
WJ-8711A RF Subsystem Functional