To: | <rtty@contesting.com> |
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Subject: | Re: [RTTY] Question |
From: | "David G3YYD" <g3yyd@btinternet.com> |
Date: | Sat, 17 May 2014 21:12:44 -0000 |
List-post: | <rtty@contesting.com">mailto:rtty@contesting.com> |
Fred If you want to know more about RTTY then have a look at Chen W7AY web site and in particular this bit of his website http://www.w7ay.net/site/Technical/RTTY%20Transmit%20Filters/index.html Also Andy Flowers K0SM has a very good article on actual TX bandwidths at his web site: http://www.frontiernet.net/~aflowers/k3rtty/k3rtty.html The first thing to know is FSK on most radios have no filtering and as you will see form Andy's web site have very wide signals. The exception to this is the Elecraft K3. The second thing is that correctly adjusted AFSK when used with a good radio has a narrow TX bandwidth without compromise to received performance. If you use MMTTY then the default setting are not good use TX band pass filter on and 512 taps. Many rigs which have too large a AFSK input signal will produce 2nd harmonic output that will cause QRM to other amateurs. This is totally avoidable by attenuating the sound card output by about 20dB, a 10K series resistor and a 1K resistor to ground will do this for you. Also make sure that the tone frequency is above 1500Hz so the SSB filter in the radio will attenuate any harmonic distortion to levels that are unlikely to cause QRM to others. 73 David G3YYD -----Original Message----- From: RTTY [mailto:rtty-bounces@contesting.com] On Behalf Of Fred Souto Maior Sent: 17 May 2014 20:23 To: rtty@contesting.com Subject: Re: [RTTY] Question Can someone pse tell me how many kcs are used by a RTTY signal ?? This is relative to people operating split and receiving up 1 Khz. Usually the TX frequency of the DX station is QRMed by the callers just 1 and some times less then 1 up. And if we have a local stn calling it's impossible to get a decent signal from the DX. Why not put the RX frequency 2 or 3 up ?? Fred - PY7ZZ --- Este email está limpo de vírus e malwares porque a proteção do avast! Antivírus está ativa. http://www.avast.com _______________________________________________ RTTY mailing list RTTY@contesting.com http://lists.contesting.com/mailman/listinfo/rtty _______________________________________________ RTTY mailing list RTTY@contesting.com http://lists.contesting.com/mailman/listinfo/rtty |
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