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Re: [RTTY] AFSK to FSK converter

To: "Joe Subich, W4TV" <lists@subich.com>
Subject: Re: [RTTY] AFSK to FSK converter
From: Frank <frankkamp@att.net>
Date: Mon, 17 Sep 2012 08:41:57 -0500
List-post: <rtty@contesting.com">mailto:rtty@contesting.com>
I used an AFSK to FSK converted box in the mid 70's to run a model 15 RTTY machine.

It took the tones from the speaker of the receiver (AFSK)(analog) and converted them to digital pulses to drive the printer. Those pulses could just as easily have been used to shift the frequency of an oscillator and generate FSK. OMG they were! The transmit signal was generated by using a relay in the loop of the printer/keyboard to turn the digital pulses into FSK.

That AFSK to FSK converted was better known as a TU (terminal unit for you novices).

Nowdays we use sound cards to do the same thing

Now anyone want to admit that this entire thread was an April fools joke?

AFSK to FSK converter indeed!

Joe Subich, W4TV wrote:


On 9/17/2012 6:40 AM, Doug Faunt wrote:
>

But the K4DSP unit should be simple enough to wire up on perf-board-
there are only a dozen components aside from the connectors.


The question is whether the K4DSP unit (QST article here for members:
http://p1k.arrl.org/pubs_archive/139117) will even work with 2Tone.

The developer of 2Tone refuses to adopt a fixed frequency mode - it's
AFSK only with AFC running all the time.  Since the K4DSP interface
expects to decode fixed frequency tones (2125/2295 or 1275/1445) how
well does it work with "drifting" inputs?

The lack of *fixed* inputs may be a serious limitation with any
regenerator - whether it be the K4DSP design of a simple PLL tone
decoder:
www.electroniq.net/radio-frequency/fsk-demodulator-using-lm565.html

73,

   ... Joe, W4TV


On 9/17/2012 6:40 AM, Doug Faunt wrote:

It's not been mentioned on the RTTY list before, just N1MM-digital, and
I'm not getting those emails (not enough bandwidth most of the time).

But the K4DSP unit should be simple enough to wire up on perf-board- there
are only a dozen components aside from the connectors.

73, doug


ORIGINAL MESSAGE:
On Mon, 17 Sep 2012 02:41:15 -0400, Doug wrote:

Obviously, I've missed something- what's "2 Tone" in this context?
Google
isn't being helpful.

73, doug


REPLY:
It's a new program which can replace MMTTY but only with N1MM.

Check the archives back a week or two.

73, Bill W6WRT
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