[time-nuts] information about the Austron Synchronous Filter 2090A

Tom Van Baak tvb at LeapSecond.com
Tue Feb 7 16:58:47 EST 2017

> Hi, any ideas on what the Austron Synchronous Filter 2090A is for?  I 
> couldn't find it in the '88 catalog.  I recall seeing some hits for it 
> in old unclassified DoD R&D publications in the past, wherein it was 
> used as part of an experimental LORAN reception setup.

>From the data sheet:

The AUSTRON Model 2090A Synchronous Filter is a Loran-C waveform averaging system that extends the range and versatility of the AUSTRON Model 2000C Loran-C Receiver in a variety of time/frequency and propagation applications.

Basically, the Model 2090A obtains a pulse waveform average that is taken over a number of pulse group repetition periods and processed for scope display or stripchart recording.

Loran-C waveform averaging accomplishes two important results:

  First, most types of coherent CW interference (communication signals, etc.) may be cancelled to zero in less than a second. This type of interference can be particularly troublesome when recording Loran-C waveforms in conventional ways.

  Second, averaging improves the waveform signal-to-random-noise ratio in proportion to the effective averaging time. Thus, it is possible to retrieve and analyze Loran-C signal waveforms that are obscured by atmospheric and manmade noise in the normal 20 KHz or 50 KHz receiver RF bandwidth.

For more details, including photo, specs and principles of operation, see:


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