[GreenKeys] ITTY 850 shift?

[Harold Hallikainen]

Great stuff! I remember the Lenkurt demod sitting on the shelf under the
model 15 at the radio stations I worked at. Also, the school newspaper at
a model 20 with a reperf. It was not a typing reperf. Something I thought
was very clever on the model 20 was that there was a bunch of overprint
garbage at the start of each story on the page printer. On the punched
tape, this garbage showed up as a dot matrix story number. The editor
would select stories from the page printer, then find the story on punched
tape using the dot matrix story number. That punched tape then drove the
Linotype.

I also remember RCA Service company coming to maintain the machines. The
guy drove a station wagon full of Teletype parts. He'd tear the machine
down, clean, lube, and replace any worn parts. It would work perfectly for
the year  until his next visit.

One station got one of those new Extel machines. The Teletype sound was
replaced by a zip-zip sound. It, like many of the dot matrix machines at
the time, would print a full line at a time. You could not see the line
until it was complete. This was fine for RO printing like wire services,
but I think would be difficult for KSR operation.

Mixing threads a bit here, I also did a lot with the Teletype 43. One of
the first products I designed was a program logging system for automated
radio stations. We bought a lot of model 43s to sell with that system (
https://bh.hallikainen.org/uploads/harold/ProgramLoggingSystem.pdf and
https://bh.hallikainen.org/index.php/HallikainenAndFriends ). I always
thought the print quality on the 43 was the best among all dot matrix
printers. It also had "last character visibility" where the print head
would move to the right on a pause in receive data so the last character
was visible. The Extel printers I saw tended to have light "wavy" caps
only text. The 43 made dark fully formed characters.

Fun stuff!

Harold
https://w6iwi.org




On Sun, February 5, 2023 7:49 am, Jeffrey Golas wrote:
>
> This is awesome, thanks! So where I see a reference to "VF", like "VF
> Demodulator", is that "voice frequency"?
>
>
> It also sounds like one they were using the Lenkurt gear they were using
> 110baud by then.
>
>
> Jeff KC3GJX
>
> On Feb 5, 2023, at 1:37 AM, Sheldon Daitch  wrote:
>
>
> 
>          I can't speak for the UPI services, because I never worked for
> UPI, but I
> did spend a year with the AP in the Raleigh bureau.
>
>
> When my hometown radio station went on the air in 1960, the AP wirefeed
> to the M-15 was a DC loop from the telco in town.  Just another copper
> pair.
>
>
> Either in the late 1960s or early 1970s, the AP went from the DC loop
> system
> to a Lenkurt 25A tone carrier system
>
> See page 15 at this link:
>
> https://worldradiohistory.com/Archive-TV-&-Communications/TV-and-Communications/TV&C-1966-03.pdf
>
>
>
> The Raleigh bureau had the rack mount system for transmission, and as best
> as I remember, the
> system had nearly all or all 25 channels populated.   Too far back for me
> to remember.
>
>
> The AP had upgraded the slow speed wire circuits to 66WPM and the Lenkurt
> system didn't seem
> to have any problems with carrying those circuits at that speed.
>
> Do a word search on the below link for a reference to the Lenkurt use by
> AP and UPI:
>
>
> https://www.smecc.org/extel_-__printers_and_reuters_and_more___.htm
>
>
>
>
>
> The AP typically used the stand alone Lenkurt box on the shelf below the
> M-15 or M-20.
>
>
> UPI was a bit more modern as they typically used the Extel printers and
> the demodulator
> was a card in the back section of the printer.  I don't remember seeing
> any Extel printers on
> the AP circuits, but since it cost extra for the AP subscriber, maybe no
> one was willing to
> pay.
>
>
> The telco line was a standard voice grade circuit.  Far too many years
> ago, I was working at
> a UPI station and the news director wanted to do live reporting from the
> county's election
> office and he also wanted the UPI feed.   I contacted the UPI and telco
> for the price to have
> a second loop at that office and was, well, astonished at the price.  It
> dawned on me that the
> UPI circuit was a simple tone multiplex system, I verified the audio with
> a telephone butt set
> and decided the cheapest route was to simply have a copper pair from the
> telco from the
> radio station to the election office.  I took the UPI tone audio, back fed
> it to the telco loop,
> took the Extel to the election office for a test, it printed perfectly and
> I satisfied the need of the
> news director for that election reporting.
>
>
> Whether the tone demodulator was UPI or AP equipment, the unit was set up
> with one tone
> filter card, with the frequency (or frequencies!) for the wire service the
> subscriber was paying for.
>
>
> Sheldon
>
>
>
>
>
>                      On Sunday, February 5, 2023 at 01:06:10 AM EST,
> Jeffrey Golas  wrote:
>
>
>
>
>
>
>
> Were those demod units a particular make and model at all? Be curious to
> learn about them. Was it truely a standard pots line or a T1?
>
>
>
> Jeff
>
>
>
>> On Feb 4, 2023, at 9:55 PM, Harold Hallikainen via GreenKeys  wrote:
>
>>
>
>> When I worked in radio stations (1970s), the AP and UPI wire services
>> had
>
>> a bunch of different TTY channels on the single telco pair. The
>
>> demodulator was tuned to whatever service you were subscribed to.
>
>>
>
>> I still plan on doing some experimenting with 850 Hz vs 170 Hz shift.
>> I'm
>
>> currently thinking that the error rate would be about the same on 170 Hz
>
>> shift with use of either a limiter or dynamic threshold control. With
>> 850
>
>> Hz shift, I think dynamic threshold control would do better since the
>
>> wider apart frequencies would fade differently (at least more
>> differently
>
>> than with 170 Hz shift). I think a fade of 170 Hz shift signal would
>
>> frequently take both tones below the noise level while with 850 Hz
>> shift,
>
>> perhaps only one would go below the noise level at a time.
>
>>
>
>> My DSP TU ( https://w6iwi.org/rtty/DspTU/ ) has a simple error counter.
>
>> The number of valid start bits is compared to the number of valid stop
>
>> bits (in a software UART). With a high error rate, the ratio of valid
>> stop
>
>> bits to valid start bits will be lower.
>
>>
>
>> It would be interesting to also implement this on a computer for testing
>
>> different terminal units under impaired channel conditions. I know the
>
>> FTDI USB/UART bridge won't go down to 45.55 bps. It looks like hardware
>
>> serial ports on PC compatible computers can hit 44.956 bps, so that
>> would
>
>> be something to try. The error rate would be the number of frame errors
>
>> divided by the number of bytes received.
>
>>
>
>> Anyway, I think there may be advantages to 850 Hz shift with selective
>
>> fading and dynamic threshold control.
>
>>
>
>> Harold
>
>> https://w6iwi.org
>
>>
>
>>
>
>>> On Sat, February 4, 2023 7:30 pm, W2HX wrote:
>
>>> Interesting idea. I'd be happy to test it. I can demodulate both
>>> shifts.
>
>>> Very interesting experiment!
>
>>>
>
>>>
>
>>> 73 Eugene W2HX
>
>>> Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos
>
>>>
>
>>>
>
>>> -----Original Message-----
>
>>> From: greenkeys-bounces at mailman.qth.net
>
>>>  On Behalf Of Harold Hallikainen via
>
>>> GreenKeys
>
>>> Sent: Saturday, February 4, 2023 9:10 PM
>
>>> To: Daniel Jones
>
>>> Cc: Greenkeys
>
>>> Subject: Re: [GreenKeys] ITTY 850 shift?
>
>>>
>
>>> I wonder if those tones (2 kHz +/- 425 Hz) are far enough away from the
>
>>> 170 Hz shift tones that both could be sent on the same channel and the
>
>>> terminal unit would demodulate the correct ones.
>
>>>
>
>>> Harold
>
>>> https://w6iwi.org
>
>>>
>
>>>
>
>>>> On Sat, February 4, 2023 6:57 pm, Daniel Jones wrote:
>
>>>> As a fellow military user I concur.
>
>>>>
>
>>>>
>
>>>>
>
>>>> Daniel
>
>>>>
>
>>>> www.K6YIC.com
>
>>>> DJones at K6YIC.com
>
>>>>
>
>>>> HH#11973
>
>>>>
>
>>>>
>
>>>>
>
>>>>> On Feb 4, 2023, at 17:54, Nick England  wrote:
>
>>>>
>
>>>>
>
>>>> Paul, definitely use these military tones and not the ham ones
>
>>>> that
>
>>>> Jim Haynes discussed. No one is running 850 shift any more except us
>
>>>> guys running military gear. Our equipment is not retunable to the ham
>
>>>> tones.
>
>>>> Thanks
>
>>>> Nick
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>> On Sat, Feb 4, 2023 at 8:29 PM W2HX  wrote:
>
>>>>
>
>>>>        That would be cool! Center freq 2000 Hz, shift is +/- 425 Hz
>
>>>> so that means the tones are 1,575 Hz and 2,425 Hz. Mark is low.
>
>>>> Someone correct me if I’m wrong.
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>> 73 Eugene W2HX
>
>>>> Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>  From: Paul Heller
>
>>>> Sent: Saturday, February 4, 2023 7:58 PM
>
>>>> To: W2HX
>
>>>> Cc: Daniel Jones ; Greenkeys
>
>>>> Subject: Re: [GreenKeys] ITTY 850 shift?
>
>>>>
>
>>>>
>
>>>>
>
>>>> Let me see what I can do. What are the frequencies for 850 shift,
>
>>>> mark and space?
>
>>>>
>
>>>>
>
>>>>
>
>>>> Paul
>
>>>> W2TTY
>
>>>>
>
>>>> ITTY:                      HTTP://INTERNET-TTY.NET:8000/ITTY
>
>>>> ITTY100:               HTTP://INTERNET-TTY.NET:8010/ITTY100
>
>>>>
>
>>>>
>
>>>>
>
>>>> AUTOSTART: HTTP://INTERNET-TTY.NET:8030/AUTOSTART
>
>>>> EUROPE:              HTTP://INTERNET-TTY.NET:8040/EUROPE
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>>  On Feb 4, 2023, at 5:53 PM, W2HX  wrote:
>
>>>>
>
>>>>
>
>>>> 
>
>>>> Thanks, Dan. I can generate the tones ok. I was just hoping that I
>
>>>> could get some news stores to print. It would be great if the ITTY
>
>>>> powers that be could just pipe the same data to both a 170 Hz shift
>
>>>> and an 850 Hz shift audio stream.  Dunno what is involved with that
>>>> but
>
>>>> just curious.
>
>>>>
>
>>>>
>
>>>>
>
>>>> 73 Eugene W2HX
>
>>>> Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos
>
>>>>
>
>>>>
>
>>>>
>
>>>>  From: Daniel Jones
>
>>>> Sent: Saturday, February 4, 2023 7:46 PM
>
>>>> To: W2HX
>
>>>> Cc: Greenkeys
>
>>>> Subject: Re: [GreenKeys] ITTY 850 shift?
>
>>>>
>
>>>>
>
>>>>
>
>>>> I had a cast set up to broadcast tty over the internet.  Let me look
>
>>>> this week and see if it’s still running on my site and the feed
>
>>>> something into it at 850 shift.
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>> You can also change the settings on the itty software to the required
>
>>>> tones to test it in-house.
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>> Daniel
>
>>>>
>
>>>> www.K6YIC.com
>
>>>>
>
>>>> DJones at K6YIC.com
>
>>>>
>
>>>> HH#11973
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>>  On Feb 4, 2023, at 16:34, W2HX  wrote:
>
>>>>
>
>>>>
>
>>>> 
>
>>>> Anyone know if there is a URL for ITTY for 850 shift?
>
>>>>
>
>>>>
>
>>>> 73 Eugene W2HX
>
>>>> Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos
>
>>>>
>
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>
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>>>>
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>>>>
>
>>>>
>
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>
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>
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>
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>
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>>>>>>> 2002-to-present greenkeys archive:
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>>>> --
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>>>>
>
>>>>
>
>>>> Nick England K4NYW
>
>>>> www.navy-radio.com
>
>>>>
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>>>>
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>>>>
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>>>>
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>>>>
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>>>>
>
>>>> ______________________________________________________________
>
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>>>>
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>>>> Jordan Spencer Cunningham's GreenKeys Search Tool:
>
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>
>>>> 2002-to-present greenkeys archive:
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>
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>
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>
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>
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>>>>
>
>>>>>>> Jordan Spencer Cunningham's GreenKeys Search Tool:
>
>>>>>>> https://teletype.net/gksearch
>
>>>>>>> 2002-to-present greenkeys archive:
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>>>>>>> http://mailman.qth.net/pipermail/greenkeys/
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>>>>>>> 1998-to-2001 greenkeys archive:
>
>>>>>>> http://mailman.qth.net/archive/greenkeys/greenkeys.html
>
>>>>>>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
>
>>>>>>> http://comcents.com/tty/greenkeyssearch.html
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>>>>
>
>>>> This list hosted by: http://www.qsl.net Please help support this email
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>
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>
>>>
>
>>>
>
>>> --
>
>>> FCC Rules Updated Daily at http://www.hallikainen.com Not sent from an
>
>>> iPhone.
>
>>> ______________________________________________________________
>
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>>>
>
>>>>>> Jordan Spencer Cunningham's GreenKeys Search Tool:
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>>>>>> https://teletype.net/gksearch 2002-to-present greenkeys archive:
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>>>>>> http://mailman.qth.net/pipermail/greenkeys/
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>>>>>> 1998-to-2001 greenkeys archive:
>
>>>>>> http://mailman.qth.net/archive/greenkeys/greenkeys.html
>
>>>>>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
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>>>>>> http://comcents.com/tty/greenkeyssearch.html
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>>
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>>
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>> --
>
>> https://w6iwi.org
>
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>
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>>>>> Jordan Spencer Cunningham's GreenKeys Search Tool:
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>
>>>>> 2002-to-present greenkeys archive:
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>>>>> 1998-to-2001 greenkeys archive:
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>>>>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
>>>>> http://comcents.com/tty/greenkeyssearch.html
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>
>>>> Jordan Spencer Cunningham's GreenKeys Search Tool:
>>>> https://teletype.net/gksearch
>
>>>> 2002-to-present greenkeys archive:
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>>>> Jordan Spencer Cunningham's GreenKeys Search Tool:
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>>>> 2002-to-present greenkeys archive:
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>>>> 1998-to-2001 greenkeys archive:
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>
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