Watkins-Johnson Company WJ-8711A Installation, Operation And Maintenance Manual Download Page 29

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WJ-8711A DIGITAL HF RECEIVER

GENERAL DESCRIPTION

1-9

1.5.9

WJ-871Y/485 485 INTERFACE OPTION

This option provides multidrop interface capability to the receiver via a rear panel connector.

Refer to

Appendix H

for further information on the WJ-871Y/485 option.

1.5.10

WJ-871Y/SEU SPEECH ENHANCEMENT UNIT

The WJ-871Y/SEU Speech Enhancement Unit option uses adaptive filtering techniques to

provide enhancement of audio signals that are received from signals in the HF frequency band. The option
utilizes these filter techniques to accomplish wideband noise reduction and automatic notch filtering of the audio
signals. See

Appendix I

1.5.11

WJ-871Y/IFC125 12.5 kHz IF OUTPUT OPTION

The WJ-871Y/IFC125 12.5 kHz IF Output Option provides a post-filtered IF output on the rear

panel of the WJ-8711A at A2J1. The ouptut center frequency is 12.5 kHz with a bandwidth equal to the
operator-selected IF Bandwidth. Refer to

Appendix J

for further details.

1.5.12

WJ-871Y/FSK FREQUENCY SHIFT KEYING OPTION

The WJ-871Y/FSK Frequency Shift Keying Option adds the FSK demodulation mode to the

standard detection modes available with the WJ-8711A. Refer to

Appendix K

for further details.

1.6

WJ-8711A SOFTWARE VERSION RELEASE HISTORY

To ensure efficient receiver operations, the WJ-8711A uses three microprocessors, each running

its own software code. The front panel microprocessor (A1A1U1) runs the front panel control code, while the
digital microprocessor (A2U1) runs the internal control code, and the digital signal processor (A2U37) runs the
digital signal processing (DSP) code.

1.6.1

WJ-8711A INTERNAL CONTROL SOFTWARE RELEASE HISTORY

The WJ-8711A internal control software is contained in EPROM A2U12. The original internal

control software, version 1.00, was released May 23, 1991.

Version 1.10 was never released.

Version 1.20, released December 20, 1991, added the following RS-232C remote commands and

queries: AGC, AGC?, BFO, BFO?, BWS, BWS?, CDE?, CTL, CTL?, DET, DET?, FRQ, FRQ?, LDE?, REF?,
RFG, RFG?, RFP, RFP?, SGV?, SQL, SQL?, *CLS, *ESE, *ESE?, *ESR?, *RST, *SRE, *SRE?, *STB?, and
*TST?. This release also allowed service request handling on the RS-232C interface. This release improved
BITE by testing the following receiver areas: the front panel, the DSP circuitry, the RF signal path, and the
audio signal path. This release set the default AGC value to FAST AGC, and the IFBW default value to 6 kHz.
This release also temporarily mutes the receiver audio when changing the RF input path. When changing
detection modes from a non-SSB (AM, FM, CW) detection mode to a SSB detection mode (LSB, USB, ISB),
this release stores the non-SSB IFBW value and selects the 3.2 kHz IFBW. When the detection mode is changed
back to a non-SSB detection mode, the previously stored non-SSB IFBW returns. This release disallowed the
preamplifier RF input path when tuned below 500 kHz. This release added the selected RF input path to the
variables stored in a memory channel. This release added the capability of clearing receiver memory by pressing
the clear entry button during power up. This release also displays the actual gain value when in the manual gain
mode.

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