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.
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. 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? Can you send chat along with the image? Or at least send chat in between images? I did not change anything for conditions and used whatever the defaults are. What are some of the options that you recommend? 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. 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. 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 Leskep wrote: > Re EasyPal > > Did you use the latest version from the KC1CS site? > > Did you use the RS encoding which is available in the program? > > Did you have one end in Repeater mode which would give you a Quasi > ARQ type system? > > Did you use a transmission mode suitable for the band conditions at > the time? > > There are many features in EasyPal which which are not well understood > by many > > I feel you should have come up with better figures than you did for > the tests > There is also a difference in transmitting a compressed picture or > sending > the file as an Anyfile which is the complete - uncompressed file > > Les VK2DSG > >
