Hi Rick see comments below 5 spaces in Les VK2DSG
From: Rick Sent: Sunday, January 27, 2008 3:38 AM To: digitalradio@yahoogroups.com Subject: Re: [digitalradio] Report on RFSM2400 vs. OFDM I was using the 10/Nov/07BETA of EasyPal which I downloaded fairly recently. I noticed that there are images that are sent with an RS 1 through 4 and then I think it converts them to jpg? I could not open those files with other programs. Perhaps you an give us some tutorial on it. The RS turned out to be Reed-Solomon coding so at least we know what is being used. Always use the latest from the KC1CS site You cannot Open an .rsx file - it is the means to transfer the file encoded and is automatically displayed in its original form at the receiving end Since it was the first time I ever tried EasyPal for transmitting, I don't have much background on this. I don't have a lot of interest in SSTV, per se, but I am using image as a surrogate for the data that I would rather be sending. EasyPal may be used for normal data transfer by loading as an ANYFILE but of course this is limited by the file size and the length of time to to transfer it depending on the mode and conditions existing at the time Because of an active group here in the midwestern part of the U.S. on daytime 40 meter SSTV (7173 kHz) I will sometimes leave SSTV programs on the frequency and automatically receive some of the images when signals are good. When you use the repeater function does that work with one to many as in nets? Or is that intended for one to one? Yes it is one to many - each station individually asking for any corrections to the original transmission by the repeater Can you send chat along with the image? Or at least send chat in between images? You can sent chat by Waterfall text or you can directly send a text message in a separate screen --- Action Send text I did not change anything for conditions and used whatever the defaults are. What are some of the options that you recommend? See prior post Based upon the conditions, and my experience with receiving (not transmitting) DRM type of OFDM data, the roughly 1/6 throughput seems about right. When conditions are very good, such as NVIS daytime on 40 meters or close to NVIS anyway, with maybe 5 or 6 S units between the noise and the signal, it is posible to receive the majority of the packets (blocks) on the first try. Use the correct mode and always use encoding suitable for the noise on the path The question becomes: if you had two modems, one using single tone high baud rate vs. one using multi tone OFDM, which one would perform the best in varying conditions. Maybe the answer is to have available BOTH and use the one which is most suitable at the time to suit the conditions Various documents on the internet suggest that there is not much difference, but there is at least one that does show a difference with computer simulations in favor of the multi tone modems. I tend to discount computer simulations as not adequate and prefer the real world under many different conditions that gives you a more accurate practical feel for what can and can not be done. That same document, done as a PhD paper, admitted that some waveforms that worked well on computer simulation, actually did not work at all in an actual real world test. 73, Rick, KV9U