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Re: Topband: Digital mode spurious issues

To: topband@contesting.com
Subject: Re: Topband: Digital mode spurious issues
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Mon, 30 Dec 2013 14:17:57 -0800
List-post: <topband@contesting.com">mailto:topband@contesting.com>
You're both right -- it is either JT65 or JT9. WSJT software, based on protocols developed by K1JT, will decode both modes. Another software package called JT65-HF will decode only JT65.

And yes, the trash Tom was hearing was either overdriven audio or a crummy radio or both. Some of the newer hams using these modes are also using pretty crummy radios -- all-banders in the $900 price range. OTOH, most are running flea power -- 20W is QRO for this crowd.

I've done a fair amount of JT65, mostly on 6M and 160M, using my K3. I've also used other K1JT modes designed for meteor scatter (FSK441) and ionospheric scatter (SCAT). JT9 is Joe's latest and greatest protocol, requiring a fraction of the bandwidth of JT65.

73, Jim K9YC

On 12/30/2013 10:30 AM, Mike Waters wrote:
I believe the mode that operates at 1873-1838 is JT65, and WSJT is needed
to decode it. I never tried it. It was developed by K1JT for weak-signal
and EME work.
http://www.physics.princeton.edu/pulsar/K1JT/wsjt.html

A common scenario with digital modes is that the audio into the mic input
is too high, causing unwanted spurs.

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