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Re: [CQ-Contest] Can you not hear me now?

To: cq-contest@contesting.com
Subject: Re: [CQ-Contest] Can you not hear me now?
From: Jim Brown <k9yc@audiosystemsgroup.com>
Reply-to: k9yc@arrl.net
Date: Thu, 15 Jun 2017 12:27:12 -0700
List-post: <mailto:cq-contest@contesting.com>
On Thu,6/15/2017 10:15 AM, John Geiger wrote:
You bring up a good point about digital modes Tor.  From watching the DX
cluster, it seemed that quite a few stations probably spent most of the
contest on 50.276 running JT65.  Also, how do you keep from QRMing each
other when several stations are all on 50.276?

Because they're NOT all on 50.276 -- each station occupies about 200 Hz of the 2.7 kHz bandpass of a typical USB circuit, AND WSJT-X is capable of decoding stations that overlap each other (and are nearly on top of each other). 50.276 is simply the suppressed carrier frequency -- the signals are spread out between about 50.2763 and 50.2788. JT9 occupies even less bandwidth -- about 20 Hz -- and has a few dB greater noise immunity. JT9 and MSK144 can be used with much shorter TX-RX sequences as well.

These digital protocols and the associated operating practices are well described in the tutorial for the WSJT-X software. Google to find it.

73, Jim K9YC

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