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 Post subject: Re: Need help identifying military HF transceiver
PostPosted: Jun Wed 05, 2019 3:04 pm 
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Joined: Jan Mon 28, 2013 9:35 pm
Posts: 1463
Location: Santa Rosa, CA
Thanks for the references John. Interesting reading!
I have heard of chirp being used to covey information.
Suspect it was an early form of packet the military used.
In one radar class I took at Stanford the prof did mention
there were ways of modulating the transmitted pulse
to encode info without affecting the performance of the radar.

This thing has bugged me since I bought it ages ago.
Hard to believe no one knows what it is. I've run out
of people to ask.
Steve

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 Post subject: Re: Need help identifying military HF transceiver
PostPosted: Jun Thu 06, 2019 3:47 am 
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Joined: May Wed 23, 2018 6:28 am
Posts: 489
The End

I think I have reached the end of information available related to CHIRP communication prior to 1980. There is no mention of hardware prior to what I included in my previous post. This seems to be the earliest research document on CHIRP communication available:

Quote:
Abstract:
The white Gaussian noise-limited channel so often assumed by system designers is encountered less and less in practice as the density and sophistication of modem communications increase. Long-range radio communications in particular tend to be limited by interference rather than by receiver noise; for that reason, the design of the signal waveform has great impact on system performance. A waveform that shows particular promise for channels such as satellite relay and HF radio is swept FM or "chirp" modulation. The chirp waveform is characterized in Fig. 1. A carrier is swept in frequency over a band W during a sweep interval T. The sweeps shown are linear and assume a square amplitude envelope of unity value, although nonlinear sweeps and shaped envelopes may be used. The sweep slope W/T may be used to convey information in a variety of ways, the simplest being +W/T for binary 1 and -W/T for binary 0 (slope-shift keying SSK). Higher order alphabets can be represented by different slopes, and amplitude can be added if desired. SSK will usually be most efficient, reserving the distinguishability of different slopes for the purpose of defining channels or addresses in multiple-access applications. The value of chirp modulation derives from its efficient use of available bandwidth and transmitter power in combating multipath and other forms of interference, including the "clutter" of other transmissions in multiple-access systems.
Published in: IEEE Transactions on Electromagnetic Compatibility ( Volume: EMC-10 , Issue: 2 , June 1968 )



This is a CHIRP ionosonde image from SDR# around 19MHz:

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19MHz ionosonde.jpg
19MHz ionosonde.jpg [ 233.28 KiB | Viewed 340 times ]


The station in the middle is irrelevant. For communication, the diagonal line would be the carrier. That tell-tale trace may be why that particular form of spread spectrum communication may have had a short life. These days you record the spectrum for use later. Transient signals now have persistence. I ran into some info on detecting spread spectrum, which the first step to deciphering it.

From talking to a former head engineer on AEGIS, there are 2 kinds of chirp it deals with. One is the CHIRP signal it transmits, but the other is the chirp return from a fast moving object. It's like the red shift astronomers deal with. It showed up in the 2012 upgrade.

I have one more unlikely shot at it. I will see someone in a few months who works in a related field. He would have to be 70 to have had personal experience, and he isn't. However, he is in a position to find out, but I don't know that he can disclose anything if he finds anything.


John


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 Post subject: Re: Need help identifying military HF transceiver
PostPosted: Jun Thu 06, 2019 10:18 pm 
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Joined: Oct Tue 11, 2016 4:41 am
Posts: 166
Location: Alexandria, Virginia
Interesting thread I'm seeing for the first time today. Steve, I can't offer anything to help, but the "Chirp" knob caught my attention as well. Close up photos would be great when possible. I'm unable to see much detail when zooming in.

Is that a digital VFO?

Brad K4RT


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 Post subject: Re: Need help identifying military HF transceiver
PostPosted: Jun Fri 07, 2019 2:03 am 
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Joined: Jan Mon 28, 2013 9:35 pm
Posts: 1463
Location: Santa Rosa, CA
Welcome to the discussion Brad. Yes, the VFO is a synthesizer driven by a
rotary pulse generator.
Steve

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 Post subject: Re: Need help identifying military HF transceiver
PostPosted: Jul Mon 01, 2019 2:39 pm 
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Joined: Jan Mon 28, 2013 9:35 pm
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Location: Santa Rosa, CA
Just found something very similar at www.navy-radio.com

Its the R-1414/URR

The internal cosntruction is identical as are some front panel details.

Nothing on the 'net about this receiver. Does anyone have one? Who made it?
Steve

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 Post subject: Re: Need help identifying military HF transceiver
PostPosted: Jul Mon 01, 2019 6:08 pm 
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Joined: Oct Fri 02, 2009 2:41 am
Posts: 124
Location: Chapel Hill NC
Not meaning to hijack a thread but you brought up the similarity - FWIW, the R-1414/URR was made by Sylvania. The R-1414/URR manual is available from www.manualman.com. It was evidently a short-lived NSA unit.
Nick

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 Post subject: Re: Need help identifying military HF transceiver
PostPosted: Jul Mon 01, 2019 6:24 pm 
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Joined: May Wed 23, 2018 6:28 am
Posts: 489
https://www.antiqueradios.com/forums/viewtopic.php?f=5&t=281743&start=20

Nice receiver. Distant cousin, at most.


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 Post subject: Re: Need help identifying military HF transceiver
PostPosted: Jul Mon 01, 2019 8:57 pm 
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Joined: Jan Mon 28, 2013 9:35 pm
Posts: 1463
Location: Santa Rosa, CA
Thanks for posting this on your site Nick. There are many similarities between
my mystery transceiver and the R-1414. The chassis layout and construction is almost identical
as are the knobs and the position of the 'unlock' indicator. So this points to it being
a low production NSA unit made by Sylvania. But much newer than the R-1414
which uses nixies. Still no idea what the model number is though.
Steve

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 Post subject: Re: Need help identifying military HF transceiver
PostPosted: Jul Tue 02, 2019 12:34 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2794
Location: Mt. Airy, Maryland
Yes, I have an R-1414. As others mentioned, made by Sylvania. There's also the R-1451/WLR-6 "Waterboy" made by Sylvania as well. Very similar to the R-1414 but in a different package. Finally Sylvania made an updated WLR-6 (don't remember the R-nomenclature) that had LEDs instead of nixies.

Sorry for the crap picture of the R-1414.


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