[GreenKeys] ITTY Poll

Thu Sep 23 15:35:54 EDT 2021

Hi Paul,

I can't decipher anything. It looks like the frequencies shifted down to around 1500-1600
Hz, but can't tune the Dovetron to anything that is decipherable.

Bill
KE3BK     On Thursday, September 23, 2021, 12:00:31 PM PDT, Paul Heller <paul0926 at comcast.net> wrote:  

 I have just restarted ITTY100 streaming at the lower sampling rates.  Give it a few minutes to reboot and let me know what happens on your end.
Paul
W2TTYi-Telex: 80003 or 468466

ITTY:   HTTP://INTERNET-TTY.NET:8000/ITTYITTY100:   HTTP://INTERNET-TTY.NET:8010/ITTY100
AUTOSTART:  HTTP://INTERNET-TTY.NET:8030/AUTOSTARTEUROPE:  HTTP://INTERNET-TTY.NET:8040/EUROPE

On Sep 23, 2021, at 12:46 PM, William Wuttke <wcwuttke at att.net> wrote:
 Paul,

Give it a whirl. I'll tune to 100wpm.

Bill
KE3BK
     On Thursday, September 23, 2021, 09:58:15 AM PDT, Paul Heller <paul0926 at comcast.net> wrote:  

 ITTY is sampling the audio at 11025Hz, 16 bits per sample, mono. When I tried going lower some said they were having trouble. I could easily try it again, but that’s where it stood a few years ago and I’ve not touched it since.
8 bit/8kHz would be an interesting test! I’m all for using less bandwith. Maybe I’ll try this on the 100WPM channel and let the users who are using it tell me how it goes. If anyone wants to be in on this test (100WPM) let me know and we will give it a whirl. If it works there, I can move the lower sampling over to the 60WPM channels.
And if you all twist my arm, we can do the test on the 60WPM channel to start with.

Paul
W2TTY

ITTY:  HTTP://INTERNET-TTY.NET:8000/ITTY
AUTOSTART: HTTP://INTERNET-TTY.NET:8030/AUTOSTART
EUROPE:  HTTP://INTERNET-TTY.NET:8040/EUROPE

On Sep 23, 2021, at 10:09 AM, Harold Hallikainen <harold at w6iwi.org> wrote:

Methods of doing AFSK Internet broadcasts like ITTY are interesting. I
thought the idea of splicing together mark and space tone files was very
clever.

I wonder about the need for audio compression. I did a microcontroller
project that streamed live audio using ADPCM and PCM. The PCM used 16 bit
samples at 44.41 kHz. But, I think for RTTY, 8 bit samples at 8 kHz should
be fine (since that's what circuit switched telephone uses). In my
application, on receiving the HTTP request, I sent the WAV header with a
very large file size, then just started sending the samples.

As mentioned, I do think the splicing of tone files is very clever!
Another method that would be interesting is direct digital synthesis.
Depending on the desired frequency, each successive sample would be some
number of steps through a sine table from the previous sample.

Anyway, interesting stuff!

Harold

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