In the second clone window running XMMT.ocx and MMTTY with the AA6YQ
profile I have set the Mode to 75 baud in RttyRite and in its MMTTY
instance. However, the decoding in this clone window is still not
perfect.
Don't even think abut using the AA6YQ profile for 75 baud. The filters
are simply too narrow for the added bandwidth. You are seeing the
effects of inter-symbol interference from channel (Mark/Space) filters
that are close to optimum for 45.45 baud but have far too much delay
for 75 baud.
The AA6YQ profile has *two* cascaded 512 tap filters in each decoder
channel - the "Dual Peak filter" as a bandpass filter and a second
512 tap FIR resonator for each channel. Each of those resonators is
35 Hz wide - far too narrow for 75 baud.
I'd copy the AA6YQ profile ... *uncheck* the Dual Peak filter on the
Demodulator tab, change the TAP in the Discriminator box to 386 and
increase the FW setting in the Pre-Filter/BPF to 150 as a starting
point for 75 baud work. In addition, I would enable ATC (AFC/ATC
tab) and set sweep to .3
73,
... Joe, W4TV
On 4/25/2013 12:41 AM, Gary AL9A wrote:
Thanks for the help Joe. I followed the new WriteLog and MK II setup
instructions at the support page and I can now send 75 baud using
XMMT.ocx using MMTTY per the instructions. I'm not sure what changed in
the setup I was already using, but obviously something got reset.
So now my situation is this. I can send at 75 baud in the main RttyRite
window and what I'm sending decodes correctly in the blue italic font.
In the clone 2Tone window Setup is set to 75 baud and the RttyRite
window has the Mode set to 75 baud. When I send a macro at 75 baud
2Tone decodes it properly in that clone window. In the second clone
window running XMMT.ocx and MMTTY with the AA6YQ profile I have set the
Mode to 75 baud in RttyRite and in its MMTTY instance. However, the
decoding in this clone window is still not perfect. I can see some of
my macro message decoding, but many of the characters are still
garbled. I'm not sure what will happen with this window under "live"
receive at 75 baud when on the air signals are coming in.
I will continue to try various things with the second RttyRite clone
window and see if I can get it to decode better. Perhaps a different
profile other than the AA6YQ one?
73,
Gary AL9A
----- Original Message ----- From: "Joe Subich, W4TV" <lists@subich.com>
To: <writelog@contesting.com>; "Gary AL9A" <al9a@mtaonline.net>; "DONALD
A HILL" <aa5au@bellsouth.net>
Sent: April 24, 2013 6:41 PM
Subject: Re: [WriteLog] BARTG 75 setup
On 4/24/2013 9:53 PM, Gary AL9A wrote:
So unless I am missing something here, when using the XMMT.ocx interface
it will not be possible to achieve 75 baud unless you use Hardware
generated FSK. But Hardware generated FSK with XMMT.ocx will produce
the buffer timing speed issue that is unacceptable. So now my thinking
is that in order to run 75 baud for the BARTG 75 I must go back and
reinstall the MMTTY plug-in and use that for the RttyRite transmit
window at 75 baud instead of XMMT.ocx? As I am typing this my mind is
now asking should I delete all my RttyRite sections in the ini file an
let WL rebuild those too? Life ain't simple out here on the bleeding
edge!
Gary,
Go to the MK II area at www.microHAM-USA.com/Support.html, download the
updated configuration for Writelog and MK II *and follow it* for the
SM6SRW MMTTY Plug-in for Writelog or the XMMT.ocx interface using FSK.
I have just checked and *both* work perfectly at 75 baud. I was able
to transmit at 75 baud and receive on a different system at 75 baud in
either 2Tone or MMTTY (using WinWarbler) as well as the decoder built
into the K3.
You *must* use MMTTY to generate the FSK - *DO NOT* attempt to use the
WriteLog software (or hardware) generated FSK. It appears that one can
not select 75 baud with *hardware* generated FSK and the SM6SRW MMTTY
Plug-in for WriteLog (although it is possible to use Hardware generated
FSK at 75 baud with XMMT.ocx).
It will be necessary to set the baud rate in MMTTY (Options | Setup
MMTTY | Decode tab) ... I recommend defining a "Profile" for 75 baud
so you can return to it quickly. Also make sure "Fixes 45.45" is *NOT*
checked in HAM Default or every time you chick "HAM" the data rate will
be reset to 45.45 baud.
Software Generated FSK is 45.45 baud only and can not be used for this
contest.
73,
... Joe, W4TV
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