Thanks for the info David, I'm hoping to find others who are using the SM1000 and FreeDV with the Icom IC-7100 radio and compare what we've done.
I am flying a bit blind with setting the power levels. I'm presuming that both the radio power output meter and my external wattmeter don't "like" the FDMDV modulation to give a true power output indication. I set the radio power output at 25% (once again presuming that 100% is 100W! :-) ), I increase drive so that ALC just indicates and I get around 3-5 W showing on the power output meter... but it's not steady, jumping around all over the place. I'm modulating via the ACC connector on the back of the transceiver, the IC-7100 has Data mode which when selected allows you to take audio from different places... in my case the ACC connector. This also turns off compression and other trickery that might mess with a data transmission. I'm using a Kenwood TS-50, SignaLink (non USB version) and a Cmedia sound card in my shack PC to decode the IC-7100. I get 0 BER, SNR of 17, but the spectrum display looks a little lumpy. I can fiddle with the output of the SM1000 over a fair range with very little change in the displayed signal and received audio. The scatter diagram also doesn't look as nice as I've seen others. The dots are most certainly grouped together, but not as tight as I would have liked. I'm hoping to get more time in the shack this weekend to experiment a bit more. 73 Michael. VK5ZEA On 26/07/2015 7:19 AM, David Rowe wrote: > Hi Michael, > > FB on getting your SM1000 up on the air - lets have a QSO some time! > > Adjusting so your ALC just moves, and 20-25 watts average power for a > 100W PEP rig is a useful rule of thumb for FreeDV 1600. The classic > "rookie mistake" is overdriving the SSB tx, which causes clipping and a > poor bit error rate at the receiver. Make sure any speech compression > is off too. > > The best way to adjust your tx drive is monitor the SNR of the signal > using a 2nd rx and the FreeDV GUI program. For example when I tx with > my IC7200, I have a FT817 nearby with no antenna and the RF gain wound > down. I feed the rx audio into my laptop and monitor the scatter > diagram and SNR. Incidentally, with my IC7200 I can't seem to get > better than 20dB, perhaps due to it's sharp tx filtering. > > I have a video that demonstrates this (and explains scatter plots): > > http://www.rowetel.com/blog/?p=3109 > > Cheers, > > David > > On 25/07/15 23:05, Michael Carey wrote: >> Hi Everybody, >> >> I've been building up a set of SM1000 cables for a few of my different >> HF radios. The main radio I use at home is an Icom IC-7100. >> I understand you set the input level to the radio so the AGC indication >> barely moves and make sure you don't stress the output stage too much... >> I've settled on around 30W output. >> >> I find that the AGC indication on my IC-7100 tends to jump around a >> little when transmitting the FDMDV signal. >> Can I use the test tone to set the transmit level and be confident that >> this is OK for FDMDV? >> >> 73 >> >> Michael. >> VK5ZEA >> >> ------------------------------------------------------------------------------ >> _______________________________________________ >> Freetel-codec2 mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/freetel-codec2 >> > ------------------------------------------------------------------------------ > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > ------------------------------------------------------------------------------ _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
