Gary, LF,
I just had a look at MMTTY and it seems pretty easy to set it to 50Hz
shift and 22Bd baudrate.
The way I did it:
1. As a start select 23Hz RTTY (in "Profiles")
2. In "Options" select "Setup MMTTY"
3. In the tab "Demodulator" change "Shift" from 23 tot 50 (it is not
a standard option, but you can just type 50 into the field)
4. In the tab "Demodulator" change "Mark" to a suitable value (that
is the audio frequency you get)
5. In the tab "Demodulator" change "Discriminator Type" from VCO to FIR BPF
6. In the tab "Demodulator" change "Tap" from 72 to 256
7. In the tab "Demodulator" click on "OK"
8. In the tab "Decode" change "BaudRate" from 45 tot 22 and click "OK"
Steps 5-7 set demodulator type, the values above are the result of
some brief dry tests and can most likely still be optimized. You can
do that in the main screen.
If WX permits (no rain) I intend to run some tests between 20:30 and
21:30 UTC on 503.5kHz in mode USB (so if you listen in LSB don't
forget to select reverse mode).
I will announce the exact hours later this evening.
Between transmissions I will listen on the same frequency.
All reports (or replies) are welcome.
73, Rik ON7YD - OR7T
At 14:14 5/05/2009, you wrote:
Hello Gary,
I had a closer look at the 23Hz shift option of MMTTY and it seems
to run at 45Bd what is on the edge regarding the shift/baudrate
ratio. That is most likely the reason why it is not so robust.
Using 45Bd at 85Hz shift would exceed the 100Hz bandwidth limit.
I guess the best option for RTTY would be a shift around 50Hz and a
lower baudrate (say 20Bd) what would well fit within the 100Hz
bandwidth and would have a sufficient shift/baudrate ratio to
provide a robust signal.
I will see if I can get such signal out of MMTTY and - if time
permits - run some tests tonight.
73, Rik ON7YD - OR7T
At 12:22 5/05/2009, you wrote:
Hi Rik,
You have experienced the same as I did with 23Hz shift, the signal needs to
be very strong to decode. It was in the last 2 minutes that I got the
partial decode.
A much better shift to use is the 85Hz which will fit into your spec.
I have had good QSO's with Chris G3XIZ in Biggleswade both of us using 85Hz.
Give that a try next time & I believe I will get a much better decode
judging by the strength of your signal.
73
Gary - G4WGT.
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Rik Strobbe
Sent: 04 May 2009 22:37
To: [email protected]
Subject: Re: LF: RE: rtty test
Hello Gary,
call the is almost right, locator completely.
But not really impressive for 500mW ERP.
I could see my signal on your grabber, some slow QSB but strong for
the last 2 minutes or so.
I used MTTY with the profile "23Hz RTTY (MTTY)" without any further
changes, not sure that this is the best mode.
So any advice is welcome.
I have also installed MultiPSK, but am still overwhelmed by the colors
and options.
I am allowed to use any digital mode as long as I stick to max. 100Hz
bandwidth.
73, Rik ON7YD - OR7T
Quoting Gary - G4WGT <[email protected]>:
> Hi Rik,
>
> This is the best I could do, it looks like almost your call sign & locator
> :-
>
> RHTQHTST DE TC(TIOJ7T OR1T JO20IX
>
> 73
>
> Gary - G4WGT.
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Rik Strobbe
> Sent: 04 May 2009 21:10
> To: [email protected]
> Subject: LF: rtty test
>
> dear all,
>
> I will run a short (10 minute) rtty test (23Hz shift) on 503.500 at 21UTC
> Reports and/or reply welcome.
>
> 73, Rik ON7YD - OR7T
>
>
>
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