> Except for the fact that PSK has no error correction, no compression, no > formatting capabilities and no way to accurately > know if the traffic was > delivered properly other than read back, your figures are fairly accurate.
David, check out our NBEMS system at www.w1hkj.com/NBEMS Many of the modes in fldigi can also be used with our flarq program, which adds ARQ (just like Winlink uses), for assuring that the traffic was delivered error-free. Instead of going into storage at an unmanned robot, we just insist that there be a live operator at both ends of the link, and that the live operator on the receiving end actually confirm delivery so the message does not lie unnoticed in an inbox somewhere. Since there is a live operator at each end, there is someone always present to check for a QSO that might be in progress on the frequency and also negotiate a QSY when necessary, which a robot cannot do. In the next release of NBEMS, we have a unique utility called "Wrap" which calculates a checksum for the file, and allows ZIP compression to be used very effectively. This makes it possible to "broadcast" messages to many (without linking!), instead of having to link on a one-to-one basis. On MARS frequenices(, which are dedicated 3K channels), instead of ham frequencies (which have to be shared by all), MT63-2000 can also be used with our flarq program for relatively fast, error-free transfers at 200 wpm. For formatting, we use"Qforms", or a Word or Excel document zipped up, "wrapped", and sent with all formatting, using any of the modes we recommend for NBEMS on either HF or VHF. We provide a variety of HF modes, hardened against static crashes, of many speeds, from MFSK16 up to MFSK64, which can be used, depending upon the path S/N and available space, without causing QRM to adjacent stations and without taking up excessive bandwidth. Using our MFSK derivatives, we can also transmit images (without error-correction) either as narrowband FAX, or as compressed zip files with error correction. The redundancy to provide error-free reception using the narrow modes is already part of the MFSK modes (i.e. FEC), which can be used together with flarq (adding ARQ) for error-free reception at a reduction in speed of one half compared to not using ARQ, but in the same relatively narrow bandwidth. Because NBEMS is not dependent upon a handfull of PMBO stations that might or might not be in range and not busy, ANY station with Internet connectivity or phone connectivity can serve as the forwarding station, and once NBEMS gets fully deployed, there can be a unlimited number of forwarding stations, drastically cutting down the time to find a station to connect with and dramatically increasing throughput beginning from first connect attempt to final message delivery. This involves as many amateurs as would like to assist, further supporting the interest in preserving the Amateur Radio Service (as an "amateur" service!), instead of moving farther and farther toward becoming a "common carrier" by using automation. Take a good look at what NBEMS has to offer, and I think you will like what you see! 73, Skip KH6TY NBEMS Development Team http://kh6ty.home.comcast.net
