Vollie, SCAMP (Sound Card Amateur Messaging Protocol), is a high speed ARQ sound card mode that is currently a "proof of concept" by Rick, KN6KB who is the current main programmer of the Winlink 2000 system. He was able to show in the last year, that 1) digital data protocols can detect a busy channel for any kind of modulation and hold off transmitting until the channel is clear for a period of time, and 2) that a high speed ARQ mode can be accomplished on moderately powerful computers (1 GHz minimum processor) running under Windows XP.
The long term hope is that the amateur community will be able to have a robust, high speed ARQ sound card mode. Because of extensive changes to the Winlink 2000 system, he has not been able to devote much time to this side project since last spring. Rick has stated that he plans to eventually release these technologies under the GPL. (For one thing, the initial underlying protocols come from Linux and RDFT). At this time, the beta programs no longer can be tested as all had self destruct timers to insure that they would not be used beyond a few months for each release. When we did test SCAMP, we found that (as expected by those of us with some previous SSTV experience) that the selected protocols require something around a 10 db S/N ratio to operate. That means that if you have a poor signal you will get zero throughput. If you reach the minimum threshold, the program is superb and can move traffic faster than Pactor 2, although not as fast as Pactor 3 although it does require a fairly wide bandwidth. Because of the pipeline design approach taken, there is minimal throughput penalty for having an ARQ mode vs. an non ARQ mode, particularly with large packet sizes. The latency would make it somewhat more difficult to use as a keyboard mode. I am very much looking forward to when SCAMP might have multiple fall back positions so that even with the worst possible conditions, you could still get some throughput and as conditions improved the modulation schemes would adjust accordingly. 73, Rick, KV9U [EMAIL PROTECTED] wrote: > What is the latest on the SCAMP mode? When will it be available? > 73 > Vollie, W4TDB > Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> 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/
