Hi Rick, At 01:24 PM 9/1/2006, you wrote: >Can you explain how it is that you can run a symbol rate of 2400 (baud) >with 188-110A and it works very well running at this extremely high >speed for HF? And yet other modes, such as Packet, don't work very well >at 300 baud, and Walt has pointed out that government studies had show >that under 50 baud was about the optimum for the types of conditions we >often find on HF?
See my reply to Mark. >Why would we not just increase the baud rate of MT-63 or MFSK16 to get a >similar speed boost if it can work that well? There is a lot of differences here, if you focus on the MT-63 part of your query that is more like the FSK aspect of MIL-STD-188-110 that we have not coded but in only BRD and at a fixed data rate. >How tight do you need the frequency tolerance to be to enhance weak >signal modes? The ICOM Pro rigs run at around 0.5 ppm, which seems >several orders of magnitude better than what some of the digital mode >programs require. I wonder how much better a weak signal/difficult >condition mode we could come up with if there was a tighter frequency >tolerance. That more than good in my book, it would be nice if everyone used such a radio, but you have guys using 1980's rigs that were the first to offer RS-232 control. /s/ Steve, N2CKH >You might recall the early developement of Clover I, by Ray, W7GHM. If I >remember right, the signal was phaselocked to WWV or other time standard >frequency. Later this was abandoned with DSP developed as a bus card and >the computer mostly being used as a dumb terminal, but it will never be >as tight a frequency tolerance as 10 e -6 or so:) > >73, > >Rick, KV9U > > >Steve Hajducek wrote: > > >Hi Rick, > > > >ALE itself is 8FSK, 125 baud, all protocols on that modem. > > > >After an ALE link, any protocol, be it an ALE 8FSK or other can be > >utilized via other modems. Built into PC-ALE/MARS-ALE is a > >MIL-STD-188-110 modem, MARS-ALE also actively supports external > >TNC/Modems. PC-ALE passive provides this support as well using any > >third party program. > > > >The MIL-STD-188-110A serial tone modem is just that, a single PSK > >carrier frequency that by the standard is locked at 1800hz using a > >constant 2400bps Symbol Rate. Then coded data rates from 75-2400bps > >and 4800bps un-coded, this is what is supported by PC-ALE. MARS-ALE > >supports 1200hz, 1500hz and 1800hz selections for the PSK carrier and > >a symbol rate as low as 1600bps (the only one that can be used with > >the 1200hz PSK carrier) to achieved lesser IF BW requirements from > >the standard 300-3300hz (3Khz). I could not make less than a 1600bps > >symbol rate work when I last was focused on that modem. Later > >standards and newer versions of '188-110 and DLP's and waveforms that > >have developed that are implemented in new hardware are much faster > >and some modems will auto adjust to different PSK carriers and symbol > >rates I have learned. At present in MARS we have all the speed we > >need with the 2400bps coded until faster CPU's come along and more > >consistent external PCSDM's are used by all stations and radios with > >better frequency accuracy and stability are being used. > > > >/s/ Steve, N2CKH/AAR2EY > > > > > > > > > > > >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 > > > > 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/
