On 11 May 2012 05:40, Bruce Perens <br...@perens.com> wrote: > On 05/10/2012 09:33 PM, David Rowe wrote: >> >> However I think any form of PSK would still require a SSB tcvr, so no HT. > > When no part of the signal is carried as an amplitude variation, it can be > amplified using a non-linear amplifier. GMSK is very definitely used this > way.
Just for the point of reference. The documentation I'm working on (it stalled a bit lately, as I've had some busy days of work, and a fair few other things stealing my time away) works with the same GSMK modem as D-star (using ON1ARF's modem implementation as a reference). But with different sync markers and frame layout. A lot of the error correction/bit scrambling ideas are being lifted straight from D-star specs (again with adjustments to suit the 2500 codec bit rate). I'd like to think I'm implementing a few improvements over D-star too. Although time will tell. But that's another story. For sure I think HF and VHF need very different approaches. We're heading in that direction. As for the issue of clipping. I'm not totally sure whether this is as applicable with your modulation or not. But, the ALC on a radio clipping a single BPSK31 signal has the effect of 1: Reducing the intelligibility of the signal at the other end and 2: Causing spurious emissions further up and down the band. This is both a waste of the power (probably causing problem 1) and will cause interference to other stations operating in the already crowded HF bands. I'll see how well I can get my target output power without ALC indication a bit later with my real world test modulation, and report back here. Best regards, Peter. ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
