DCS is a FSK signal centered around 5 kHz. See here: http://mmi-comm.tripod.com/dcs.html All you need is a high pass filter at 300 Hz and a low pass at 4 kHz to remove it. Do you need to decode the DCS signal?
Steffan Von meinem iPhone gesendet > Am 30.07.2014 um 21:09 schrieb Bjorn Roche <bj...@xowave.com>: > > Thanks for all the info so far. I should have been more careful when I said > DCS > is a square wave. It's probably more accurately described as an NRZ code. > Nevertheless, these suggestions are very useful. > > thanks > > bjorn > > >> On Wed, Jul 30, 2014 at 2:36 PM, Bogac Topaktas <bo...@bteaudio.com> wrote: >> >> The most efficient way is to use adaptive noise cancellation. See: >> >> >> http://people.ece.cornell.edu/land/courses/ece4760/FinalProjects/s2008/rmo25_kdw24/rmo25_kdw24/index.html >> >> http://www.dsprelated.com/showmessage/5838/5.php >> >> http://www.cs.cmu.edu/~aarti/pubs/ANC.pdf >> >> It works perfectly for removing 50/60Hz hum from single coil >> pickups of electric instruments, where static notch filtering >> is not adequate (see first reference above). >> >> In the worst case, i.e., if you can't construct a perfect cancellation >> signal, you may recover spoken words with a robust speech recognizer and >> then synthesize a clean speech afterwards. >> >>> On Tue, July 29, 2014 6:32 pm, Bjorn Roche wrote: >>> Hey all, >>> >>> >>> I'm dealing with a non-music but still audio-related DSP issue. I need >>> to remove a DPL/DCS signal from a recording. Roughly speaking, a DCS >> signal >>> is a low frequency (67.15Hz) square wave sent at the same time, over the >>> same carrier, as speech. Because it is a square wave, it has many strong >>> harmonics that overlap with speech. Obviously, the speech must be >>> preserved as well as possible and the goal is to reject the DCS as much >> as >>> possible because it's annoying as all get-out. >>> >>> On the surface, this seems like a problem that might be solved the same >>> way as removing 60Hz power-line noise: lots of notch filters. However, >>> power-line noise tends to be weaker and comes from a source that is much >>> closer to a sine wave. >>> >>> So, my question is: is there a better way to do this? (preferably >>> something someone has experience with) >>> >>> This link contains more info about DCS: >>> http://onfreq.com/syntorx/dcs.html It >>> mentions "Since DCS creates audio harmonics well above 300 Hz (i.e. into >>> the audible portion of the band from 300 to 3000 Hz), radios must have >>> good filters to remove the unwanted DCS noise." Ha! I've asked this also >> on >>> stack exchange here: >> http://dsp.stackexchange.com/questions/17462/filtering-out-unwanted-squar >>> e-wave-radio-dcs-dpl-signal >>> >>> TIA! >>> >>> >>> bjorn >>> >>> -- >>> --------------------- >>> Bjorn Roche >>> bjornroche.com <http://blog.bjornroche.com> @xonamiaudio >>> -- >>> dupswapdrop -- the music-dsp mailing list and website: subscription info, >>> FAQ, source code archive, list archive, book reviews, dsp links >>> http://music.columbia.edu/cmc/music-dsp >>> http://music.columbia.edu/mailman/listinfo/music-dsp >> >> >> -- >> dupswapdrop -- the music-dsp mailing list and website: >> subscription info, FAQ, source code archive, list archive, book reviews, >> dsp links >> http://music.columbia.edu/cmc/music-dsp >> http://music.columbia.edu/mailman/listinfo/music-dsp > > > > -- > --------------------- > Bjorn Roche > bjornroche.com <http://blog.bjornroche.com> > @xonamiaudio > -- > dupswapdrop -- the music-dsp mailing list and website: > subscription info, FAQ, source code archive, list archive, book reviews, dsp > links > http://music.columbia.edu/cmc/music-dsp > http://music.columbia.edu/mailman/listinfo/music-dsp -- dupswapdrop -- the music-dsp mailing list and website: subscription info, FAQ, source code archive, list archive, book reviews, dsp links http://music.columbia.edu/cmc/music-dsp http://music.columbia.edu/mailman/listinfo/music-dsp
