[digitalradio] Re: Recent MFSK16 DX
--- In digitalradio@yahoogroups.com, Vojtech Bubnik bubn...@... wrote: In a simple shoot out between olivia 250 x8 and msfk16 , olivia stopped decoding whilst mfsk was still at 100% ... thought that was not supposed to happen ? Hi Graham. I am certainly not surprised and it confirms my Gaussian noise tests. Olivia trades sensitivity for automatic tuning. MFSK16's convolution coding provides for high sensitivity, but does not give sharp enough indicator, whether the data is valid. Basically the Hammond distance of the code is too low to give reliable indicator. Olivia uses Welsh block coding, which provides good data validity indicator, but has not as high coding gain as convolution codes. For explanation of coding gain, see the excellent article from g3ruh http://www.amsat.org/amsat/articles/g3ruh/105.html I believe the perfect weak signal mode for HAM radio is yet to be designed with easy tuning of Olivia and high sensitivity of MFSK16, combining both convolution and block codes. Maybe overlying MFSK16 with Reed-Solomon block code and running multiple MFSK16 decoders with half tone spacing will do the trick. 73, Vojtech OK1IAK The other thing was the initial test was mt63/500 ~ olivia 250 x 8 , MT dident do very well, so ended up with mfsk .. the single tone is handy as well , as many lf stns cannot handle linear modes like psk .. but with the stability of modern rigs I dont see why the original mfsk should not make a come back ? G ..
Re: [digitalradio] Re: No PTT, FLDIGI with ICom 746P and Digikeyer
Contgratulations, Andy! 73, Skip KH6TY - Original Message - From: Andrew O'Brien k3uka...@gmail.com To: digitalradio@yahoogroups.com Sent: Monday, February 16, 2009 7:19 PM Subject: [digitalradio] Re: No PTT, FLDIGI with ICom 746P and Digikeyer Skip, FYI... Success, we have his Digikeyer , FLDIGI and Icom 746 Pro playing together nicely. We have up on RIGCAT and tried HAMLIB again. Using one port for rig control and another for PTT in Microham's device router, we have all going well. Look for Ted W3VG dominating the PSK bands tomorrow :) Andy K3UK Andy K3UK--- In digitalradio@yahoogroups.com, Andrew O'Brien k3uka...@... wrote: Skip, thanks again. I am familar with Microham and its device router, my friend has that installed and working correctly. The Icom and the digikeyer can communicate without problems. It is when we try to set up FLDIGI that the problems begin. Using hamlib we can get frequency read out but no PTT. When we try rigCAT we get neither, and NO CAT is displayed in FLDIGI just above the frequency readout. We will work on it some more tomorrow night Andy --- In digitalradio@yahoogroups.com, kh6ty kh6ty@ wrote: Andy, here you say he has frequency display, but now you say he does not. According to the manual, he has to CREATE virtual ports. I guess you do this and then configure fldigi to use the port of your choice, but it must not be a port already in use. When the ports are created, I think fldigi will detect them, so restart fldigi and then choose the port. 73, Skip KH6TY - Original Message - From: Andrew O'Brien k3ukandy@ To: digitalradio@yahoogroups.com Sent: Sunday, February 15, 2009 4:11 PM Subject: [digitalradio] No PTT, FLDIGI with ICom 746P and Digikeyer I am trying to help a friend set-up FLDIGI on his new laptop using his Microham Digikeyer. Using the device router for the digikeyer (control port 5 and PTT port 6) the digikeyer PTT test button does toggle the PTT. However when using FL-Digi , frequency display corresponds with the Icom 746 but the T/R button fails to place the Icom in to transmit mode. Any ideas ? When configuring FL-DIGI, we did try to use HAMLIB and PTT via CAT control, but that did not produce a PTT wither. Andy K3UK Internal Virus Database is out of date. Checked by AVG - http://www.avg.com Version: 8.0.138 / Virus Database: 270.10.15/1921 - Release Date: 1/28/2009 6:37 AM Internal Virus Database is out of date. Checked by AVG - http://www.avg.com Version: 8.0.138 / Virus Database: 270.10.15/1921 - Release Date: 1/28/2009 6:37 AM
[digitalradio] Comparison of Performance of Digital Modulation in the Presence of adjacent QRM
FYI, anyone have the full articel ? Andy Comparison of Performance of Digital Modulation Techniques in the Presence of Adjacent Channel Interference Milstein, L. Pickholtz, R. Schilling, D. Univ. of California San Diego, La Jolla, CA, USA; This paper appears in: Communications, IEEE Transactions on Publication Date: Aug 1982 Volume: 30, Issue: 8 On page(s): 1984- 1993 ISSN: 0090-6778 Current Version Published: 2003-01-06 Abstract The performance of four digital modulation techniques are compared to one another when each is received in the presence of adjacent channel interference. The interfering waveforms that each modulation format sees are identical to the modulation format under consideration. The four types of modulation are QPSK, 8-PSK, 16QASK, and QPR. Upper bounds to the probability of error are derived and used to evaluate the relative merits of the different schemes. .
