>Enable your RF attenuation and increase the volume. This can help keep a >strong signal from wiping out the weaker ones. >Attenuation will probably be around 20 dB, but by dropping the noise level, >the signal readability may improve. >AGC (Automatic Gain Control) does nothing for a weak signal; it only levels >the louder ones.
This is a fairly stupid advice, and if you follow it you will miss about 50% of the fun. First thing to do of course is make sure THERE ARE NO STRONGER ONES. In the good old days of CW (an ancient digital mode which was heavily used by older generation hams) we used so-called X-tal filters to filter out signals on a different frequency than the one we worked on. This worked perfectly. Since hams started tuning with clicking a mouse instead of turning a frequency dial this became impossible. QSB on a PSK signal can amount to 80 dB, and using (slow) AGC is a must if you want to copy the weak ones. It also helps to pull weak signals out of noise generated in later stages of the RX. Just using an RF attenuator because there is a strong alien signal within your passband is the WRONG weapon against this. Moreover, NO RX IS LINEAR,so it will produce mixing products which will hit your weak signal. if you want to really take advantage of the small bandwidth why add all that bad stuff on the RX side? To make copy more difficult? Come on, with CW there was an operator who did the decoding. You cannot expect a computer to be as efficient as that. So why not help the poor DSP and filter out noise and crap BEFORE it enters your sound card? 73, Rein EA/PA0R/P (sorry to hit on the same nail over and over...) -- http://pa0r.blogspirit.com Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/sked Check our other Yahoo Groups.... http://groups.yahoo.com/group/dxlist/ http://groups.yahoo.com/group/contesting http://groups.yahoo.com/group/themixwgroup Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
