Hi All, A Yahoo search on "blanker powerline noise" led me to a thread on this mailinglist in May 2011 so now I now joined this list:-)
Kerry Miller wrote: > I'm not a software guy so pardon me if this is a stupid > question. On my Yaesu FT-990 and pretty much every other > HF rig I've ever used when you turn on the noise blanker > it causes splatter and overload if there are any strong > signals anywhere close. I've noticed the same thing on > my Flex 1500. Powerline noise can be removed efficiently in an SDR. The trick is to first identify and remove strong signals and then apply the blanker to a passband with noise and weak signals only. I is well known that blanker operation fails when strong signals are present. It is easy to demonstrate in a lab environment. I am the author of Linrad and I can demonstrate with lab-generated signals how strong signal do not degrade blanker performance in Linrad (contrary to other SDR softwares.) Performance with "ideal" signals is one thing and real world signals might be something else. The strong signals would be modulated and they would come and go. Pulses may be distorted in various ways etc. I have been searching for a wideband recording which contains powerline noise plus weak and strong signals. A wideband recording that one can play back in the SDR program to run the same sequence with and without blankers and optimize settings for best possible result. What I need is a recording where the best possible result is not very god. It should be very obvious that strong signals degrade blanker operation because the strong signals vary with time. The recording should have some part where the blanker works reasonably well and another part where the blanker does not work well - or not works at all. I would like to come in contact with operators who have a really bad powerline QRM situation and who have an SDR with software that allows recording at 96 kHz or higher. I would like a wideband file as above plus an ordinary .wav file with the best loudspeaker output that can be made with the SDR software. Presumably PowerSDR for members of this list, but for my project any SDR system wouldbe fine. I would like to upload the files on the Internet together with the loudspeaker output from Linrad on the same sequence. In case the differences turn out to not be as large as I hope they should be, such a file would be very valuable for finding out how to improve the algorithms to fix the problem. Files can be up to 700 megabytes and I can supply an FTP site for upload. If you think you can contribute, please send a mail to leif at sm5bsz.com 73 / Leif _______________________________________________ Flexedge mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used for posting topics related to SDR software development and experimentalist who are using beta versions of the software.
