[aprssig] PSK31 and OLPC?

Scott Miller scott at opentrac.org
Mon Nov 12 17:15:02 EST 2007

I was really just talking about the BPSK and QPSK modulation formats, 
not PSK31 as a whole, with varicode and everything.  Yeah, it'd need 
FEC, compression (LZW maybe), and a lot of other stuff.  But BPSK still 
seems like a good modulation choice for a low-power HF uplink.  It's 
certainly not the only option.

Assuming your coordinating/downlink stations are running a whole lot 
more power, you could use some other format on that side.


Jim Lux wrote:
> While the idea of a little HF modem that hooks up to the OLPC is interesting, I don't know that PSK31 is an appropriate modulation format.  Recall that PSK31 was designed with different design constraints than the sort of wide area tactical comms that Bob is talking about.  It had to run on a limited horsepower PC (substantially less than the OLPC has), be suitable for ham-to-ham keyboard interaction (not message passing), and, not least, had to be something that the originator felt comfortable implementing.
> Just because it is popular with hams does not mean that it is a good choice for non-ham HF comms.
> For message passing, I think there are better choices. One might want to have some form of FEC, for instance.  With the processing available in the PC, one can probably use more sophisticated signal processing.   Why not use something like MIL-STD-188 ALE?
> Jim, W6RMK
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