I have been looking through the internet to find more information on all these alphabet soup modems. Here is a very interesting web site that lists not only the various types of waveform bps rates, but also the S/N ratio for these modems to work properly. Unfortunately, the baud rate is never mentioned:
http://www.rapidm.com/standard_performances.shtml#STANAG%204285 If I am reading this information correctly, these modems don't have much application for what we have been talking about here. They require VERY high S/N ratios to work for any kind of speed. Like 10 to nearly 30 db. In fact, the very best they can do at the 75 bps rate, is around -5 db S/N with the particular modem product. And that is better than the requirements of the standard. After all the talk for weeks about how we need to get out of the technology jail that Bonnie keeps claiming, I question whether we will want to run 2400 baud modems on HF frequencies except in special cases such as when we are operating under the best conditions and very close to the MUF. These modes are supposed to be able to run under multipath spreads of 5 to 10 ms. Even with serious coding, one wonders how you can do that with a baud rate of under 0.4 ms if you use a baud rate of 2400? What would be the point of doing this when we have modes that go way, way, deep into the noise that are already available to us? The typical waveforms are just like the ones we already use, e.g., BPSK, QPSK, 8PSK, 16QAM, etc. Isn't much of this already available with the digital data transfer programs already available to the amateur community? Either RDFT types such as Digtrx, or QAM types such as Windrm? 73, Rick, KV9U 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/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> 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/
