[GreenKeys] Diversity reception back in 1959

[Ralph Irish]

When I was a Navy Radio Operator on the USS Hancock in the late 50s, we used diversity as much as we could.

We had to monitor what was called the "Fleet Broadcast" which was general, unclassified or classified-
encrypted messages.  Since the ship was on the move, fading signals was a real problem.  The NavCom shore
stations would broadcast a given signal on as many as 8 HF channels, and using the various antennas we had
on board, several different receivers and AN/URA8-A 'Stacks', we would have a pair of frequencies locked
in and fed to two Teletype converters, (the top and bottom elements of the 'stack') and the Comparator, (the
center element) would select the best signal and send it to the Teletype machine.  That was one area of the
comm. business which was complete magic to me, and fortunately I was never responsible for keeping things
running.  I spent most of my watches looking at a Model 28 or a Model 19, hoping to be able to present clean
copy to the Radio Central NCO.

We used AN/SRR receivers and when we were on deployment to the Far East, we were allocated an extra R-390.
It was picked up at the NavComSta in Hawaii on our way west, and returned when we were heading home.  I have
to tell you that we really hated to give that up!  The other two R-390s were use in conjunction with an
AN/URT-17 multi-mode transmitter in what was called the "High Command Net".  This was a radio circuit that
theoretically kept us in touch with the Chief of Naval Operations 24/7.  THAT  operating position had two
of the 390s and a pair of TMC SSB slicers and the RRS interface to the URT-17.  There was a log kept there,
on a typewriter, and every attempt or complete transmission/exchange was logged for future reference, and
I believe we were responsible for keeping track of the pair of frequencies in use when a successful or
unsuccessful contact was made/attempted.

- - - -

When we went to a scrambled Fleet Broadcast, using first the KW-26 equipment, we comandeered one of the
four URA8A stacks for our use, and a pair of receivers, and we typically had the best of the receiving
antennas available to us.  Missing traffic was not good and continually asking for repeats of particular
messages probably brought some unwanted scrutiny of our operation.

I would guess that this would be considered SPACE DIVERSITY, since the two signals we were copying may have
originated in transmitting stations miles to hundreds of miles apart.

Our plain voice callsign was RAMPAGE, and the CW and RTTY call was NWLD.

- - - -

For now,

Ralph - W8ROI

- - - - - - - -


On Mar 24, 2013, at 5:10 PM, greenkeys-request at mailman.qth.net wrote:

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> Today's Topics:
> 
>   1. Northern Diversity Converter (Larry Tighe)
>   2. Diversity (Jeffrey D Angus)
>   3. Re: Diversity (John Vendely)
>   4. Re: Diversity (Richard Knoppow)
>   5. Re: Diversity (Charles Ring)
>   6. Re: Diversity (Larry Tighe)
>   7. Re: Diversity (Richard Dillman)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Sun, 24 Mar 2013 13:35:42 -0400
> From: "Larry Tighe" <larryradio at att.net>
> To: "Greenkeys Greenkeys" <greenkeys at mailman.qth.net>
> Subject: [GreenKeys] Northern Diversity Converter
> Message-ID: <3F68434B4F7C4E6A9E2C45656F42A6B0 at d2400>
> Content-Type: text/plain; format=flowed; charset="Windows-1252";
> 	reply-type=original
> 
> FWIW
> 
> Vintage NORTHERN RADIO FS DIVERSITY CONVERTER Type 174
> 
> http://www.ebay.com/itm/200907548472?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 
> 
> 
> 
> ------------------------------
> 
> Message: 2
> Date: Sun, 24 Mar 2013 12:49:37 -0500
> From: Jeffrey D Angus <jdangus at att.net>
> To: greenkeys at mailman.qth.net
> Subject: [GreenKeys] Diversity
> Message-ID: <514F3CB1.8050000 at att.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> Looking at that converter Larry posted, does anyone actually RUN
> diversity on reception these days?
> 
> Diversity to me brings up images of a pair of large antenna arrays,
> and two Collins R-390As with a complex "voting" system to decide
> who's got the best bits to decode.
> 
> Which leads to my next question. Is there any "modern" diversity
> software out there. Something that can, for example, talk to a pair
> of CAT enabled transceivers and a pair of sound cards like the USB
> SignaLink series?
> 
> Jeff-1.0
> wa6fwi
> 
> 
> 
> ------------------------------
> 
> Message: 3
> Date: Sun, 24 Mar 2013 16:14:13 -0400
> From: John Vendely <jvendely at cfl.rr.com>
> To: greenkeys at mailman.qth.net
> Subject: Re: [GreenKeys] Diversity
> Message-ID: <514F5E95.5010306 at cfl.rr.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> Hi Jeff,
> 
> Diversity reception is still common on HF, but its implementation has 
> changed a lot since the R-390 era.  Space diversity is much less common 
> now, with frequency or time diversity (or both combined) being more 
> common.  In many cases, such diversity features are built into the modem 
> waveforms themselves, and do not require separate receivers.
> 
> A good example of this is the older BR-6029 time/frequency diversity 
> modems made by Barry Research, in which a binary bit stream was 
> distributed over 8 FSK tone pairs, each shifted one second in time.  The 
> BR system has been virtually abandoned, but there is some occasional 
> amateur use of these modems.
> 
> More sophisticated implementations of the time/frequency diversity 
> concept exist in most of the new DSP-based modems used by the military.  
> Some systems achieve frequency diversity through use of independent 
> sideband, in which the modem signal is transmitted on both sidebands, 
> which tend to fade  independently of each other. Military Link-11 
> systems on HF commonly use ISB for frequency diversity.  Some ISB 
> systems also introduce a time delay into one sideband, to achieve time 
> and frequency diversity.
> 
> Of course, there's relatively little use of binary FSK on HF compared to 
> just10 years ago, but I have recently heard some frequency diversity FSK 
> systems still in use.  The FSK channels were spaced by some 10s of kc, 
> but they were definitely carrying the same (encrypted) data.  And of 
> course, wide shift FSK (850 or 1000 Hz shift) inherently has some 
> diversity of tone fading which the better modems make use of.  The 
> Russian navy still has a few 1kc or 1.2 kc shift FSK systems in use.
> 
> 73,
> 
> John K9WT
> 
> 

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