Based on what I know, for SMTP, JNOS may be an option at less than 300 baud, i.e., 100-110 baud or PAX, using MultiPSK as "soundcard modem".
I have not tested any of it yet. I have had no time and possibilities to test it so far. JNOS can use FBB compression or LZW compressed SMTP on any of its radio ports using KISS protocol to connect to a TNC. I ran both FBB and JNOS simultaneously for several years sharing the same TNC under MSDOS and Linux, and HF mail using compressed FBB protocol or LZW compressed SMTP worked, even when painfully slow, at 300 baud on a shared forwarding frequency. Even FTP worked (I do not remember if it could be compressed as well) on HF. It is not theoretical. JNOS networking works on HF with the known 300 baud weaknesses. How well does it work really matters when nothing else is available? Certainly, that may be an option in an unconnected scenario. I have also read some papers (which are not recent ones) mentioning the possibility of using JNOS for armed forces communications. I believe it should be tried out. Configuring JNOS is not easy, it is command line oriented and learning its options is a steep process not suited for the faint of heart, because along its history, it has been developed and maintained by people familiar with Unix, networking and text mode consoles in a spartan command line environment. Working options may be saved in a configuration file that it reads at the start up. One almost miraculous option it has is the maxwait parameter. It limits the usual TCPIP exponential backoff to a value of your choice (not arbitrary, it basically depends on the signalling speed and channel reliability or congestion), indispensable when running TCPIP on a radio link and not on a high speed, less noisy, wired environment. Other TCPIP implementations fail without this "kludge", particularly, on HF radio. Even Linux with its native TCPIP stack is subject to fail as well. JNOS packet stack is better crafted than the Linux AX.25 support. Alan is right, maybe a kludge between an AX.25 stack and other modes could be devised, but it is not simple. If other sound card modes work at the same speed, why wouldn't PAX or slow packet work? APRS has been tested so far with slower than 300 baud speeds and has worked, even with the nowadays prevalent bad HF propagation. Frugality in message content is *INDISPENSABLE*. Compression is your friend. In a bandwidth limited radio channel, concise, short, text messages are preferable to more voluminous file formats (.doc, .xls, .bmp, etc). If that is not acceptable, then, who needs that should procure a wideband VSAT link. 73, Jose, CO2JA --- John Bradley wrote: > What would be our non VHF options? > > John > VE5MU VI Conferencia Internacional de Energía Renovable, Ahorro de Energía y Educación Energética 9 - 12 de Junio 2009, Palacio de las Convenciones ...Por una cultura energética sustentable www.ciercuba.com
