Mark, I think I understood you to say earlier that the baud rate is based upon the total waveform. I am having difficulty grasping what that really means. I have spent a LOT of time researching this on the internet and not really finding something that I can picture in my mind like I can with rtty and Clover, etc. which I think I sorta understand.
If I gave you some parameters of a waveform, what would you use to base your measurement of baud rate? Are you saying that the reason that packet performs so poorly is due the fact that it has no convolutional coding or interleaving? All along what Walt and I have pointed out was that ISI becomes intolerable with difficult propagation conditions (e.g., doppler, polar flutter, etc.) with short symbol lengths. The longest symbol length possible for 300 baud is 1000/baud or 1000/300 = 3.33 ms. That is a very short pulse for HF. That is why Pactor chose 100 baud = 10 ms minimum pulse length (assuming they are continuous with no gaps). That 10 ms length is about the right amount, particularly with some DSP enhancements. If the baud rate of a waveform was 2400 as Steve has often mentioned, wouldn't the longest possible symbol length be about 0.42 ms? If this really can work on HF, it is completely contrary to what I have learned over the past few decades, particularly when Pactor was first on the scene. Even with extensive DSP, can you overcome that large of an ISI issue? 73, Rick, KV9U Mark Miller wrote: >After further reading I understand now how it works. The symbol rate is >2400 Baud. The coded (rate 1/2 convolutional ) data rates have differing >interleaving depths. 75 has the highest interleaving depth, and 2400 has >the lowest interleaving depth. 4800 is not coded nor interleaved. Olivia >does something very similar. It has multiple Baud rates, and interleaving >depths. Packet has no convolutional coding, and does not interleave data. > >73, > >Mark N5RFX > >At 11:51 AM 9/1/2006, Mark Miller wrote: > > >>>The 2400 and 4800 baud is a composite baud rate for the mode/protocol NOT >>>the discrete baud rate of any individual component of the waveform. >>> >>> >>Can you explain further? I saw that: >> >>"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. >> >>The symbol rate is 2400 Baud, so what makes this perform better than >>Packet at 300 Baud? >> >>73, >> >>Mark N5RFX >> >> >> >> > > > >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/
