> I earlier mentioned ARQ in real time, but if you use the programming > technique that KN6KB used when he developed SCAMP, (Sound Card Amateur > Messaging Protocol), he used RDFT. While this was not practical to > decode during each cycle, he was able to work in the background with the > past packet that was received and do the necessary processing. >
In pskmail the receiver tells the sender what to send next. This is necessary to prepend missing blocks to the next frame. This way you can realize a full duplex k-to-k mode. When downloading a file on a good channel you send 8 blocks x 64 = 512 characters in a frame before you listen for the ack. At PSK250 this is faster than reading speed. > I have seen some multiipath, especially when I have tested PSK31 on VHF, > but much of that was from aircraft. I am not sure how I can discern > multipath when on HF. Is there any clue in the waterfall or do you go by > the sound? > You see it in the phase indicator and in the quality indicator (horizontal bar below the phase indicator). Typically happens when F1 and F2 propagation takes place simultaneously, especially in mountainous areas. At home I live near Eindhoven airport and the airplane echo doppler also happens on 30 meters. You don't see it on the S-meter, but the 2 signals corrupt the phase completely which is visible on the quality indicator. At this moment IS0GRB-3 is still S8 on 10148.25, noise (from switching power supplies in neighbouring campers) is S5, with peaks to S9+10. Fldigi log: RX (2008-03-02 22:02Z): - 2e<US><SOH>00uIS0GRB-3:72 Pskmail Server v.0.5.4.1 -Cagliari (Sardinia IT) RX (2008-03-02 22:03Z): - 22:03:02 18FA<EOT> TX (2008-03-02 22:07Z): <US><SOH>00uPA0R:26 &&185C<EOT> RX (2008-03-02 22:07Z): <US><SOH>QSL PA0R de IS0GRB-3<EOT> RX (2008-03-02 22:09Z): <US><SOH>0"kIS0GRB-3:24 DB3CF:1024 5AE26<EOT> RX (2008-03-02 22:09Z): <US><SOH>0"p E5FE<EOT> error-free channel at the moment. The other 3 servers are now gone completely. 73, Rein EA/PA0R/P -- 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/
