Receiver Processing and Control System
The SYS-1 is 4 separate 1U rackmount units
designed to do the following:
1. Control and process several receiver
functions (no DSP)
2. Preselector filter and precondition
incoming RF signals.
3. Control and amplify recovered audio
4. Filter and equalize recovered audio.
This is a computer graphic of the four front
panels. Meter placement is indicated for the
The printout of the first two modules; the Equalizer and the
Note that these are designed, printed, trimmed and applied
to the panel in modular fashion. This makes parts
placement, alignment and assembly much less
complicated. Also, any revisions can easily be done to one
section without affecting the whole panel. Of course,
another reason for the modular technique is that the
panels are 19 inches and the printer only handles 11
This is the Controller panel and its decal from the above
artwork. The individual modules are: Carrier Trigger for
COR (carrier operated relay); Demod Status to detect an
open carrier from a carrier with data; Det Drive to manually
adjust (and monitor) the drive to the demod circuits for
most linear and clean audio; a modulation percentage
meter stage, and finally an audio (line out) gain stage to
drive a console, phone line or studio link.
Bottom Panel: The finished Equalizer in beta-test. It has octave-band filters for +/- 15 dB centered on, 100, 200, 400, 800, 1.6K, 3.2K, and 6.4K Hz. It also has input
and output drive controls with meters.
Top Panel: The Control and System Monitor panel. The carrier Trigger module has a built in 5-second delay to not confuse pauses between words or data with loss
of signal. The Demod Status module is balanced to indicate a dead carrier against one with data (voice, music, Morse Code, Data Streams, etc.) The Balance
control allows for sensitivity adjustment during noisy band conditions, lightning crashes, or adjacent QRM. The Detector Drive controls external feed or local
monitoring. The Modulation meter references average data (signal) to carrier level and is indicated in percentage. The last module is Audio Line Feed, 600 Ohms,
in VU and dB.
Here's the Equalizer in actual use with the EAS-3 receiver.
The control and spectral management of recovered audio
becomes an obvious necessity once experienced.
Modified meter faces for use in the SYS-1 system.
Face decals done in Pagemaker and Corel
Photohouse on peel 'n' stick label stock.
Some of the Preselector component modules
Inside of the Preselector front panel. Components mounted...ready for wiring.
Snaps of the front panel layout
The 1U (1.75 inch) finished panel.