Basically ofdm does the fundamental trick, yes. But that alone doesnt address many issues. When ofdm went mobile, with rayleigh fading paths, such as moving trains/metros, ofdm alone doesn't keep up. Hence vendors had to look for alternatives such as diversity and many others, while facing the never ending issue with the hunger for more bandwidth. You can see the issue described clearly in this article https://cdn.rohde-schwarz.com/pws/dl_downloads/dl_application/application_n= otes/7bm05/7BM05_1E.pdf Cheers, Manu On Thu, Dec 28, 2017 at 1:49 PM, Forrest Christian (List Account) wrote: > The primary benefit of ofdm is to permit the correlation of signals > traversing multiple paths, in may cases turning multipath into a positive > thing. I'm pretty sure that the issues you described with multipath and > higher order modulation is why pretty much every modern spread spectrum > radio runs some form of ofdm modulation. > > Out of curiosity I looked to see what code is out there for ofdm. Seems > like a few options are out there. Of particular interest might be gnu > radio and the various matlab or matlab like sources. Seems to be a few > others as well. > > > > > On Dec 27, 2017 11:59 PM, "Manu Abraham" wrote: > > DVB-T with Diversity switching deploys a single demodulator with multiple > antennae and LNA's. depending upon the feedback from the individual > AGC's the LNA/Antennae are switched correspondingly to avoid reflected > paths and or to look at higher signal strengths. > > The higher the modulation order, the greater the pain you have with > reflections/doppler effect. Diversity was introduced with mobile DVB-T to > address the multipath issue to a certain extend. > > Cheers, > > Manu > > > On Thu, Dec 28, 2017 at 8:10 AM, Harold Hallikainen > wrote: >> Both interesting ideas. Our current receivers have photodiodes pointing = in >> all directions. It would be interesting to have them pointed in only one >> direction to minimize reflections. Also, short high speed transmissions >> with a gap to allow for reflections to die out is interesting. >> >> Harold >> >>> Would it help to have a high / central location reflector (or just plac= e >>> the tx/rx there) that gave a good line of sight 1st path at all times. >>> >>> Would burst transmission help with fast data rate bursts followed by >>> longer >>> quiet periods to allow echos and longer paths to fade. >>> >>> Russell >>> -- >>> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >>> View/change your membership options at >>> http://mailman.mit.edu/mailman/listinfo/piclist >>> >> >> >> -- >> FCC Rules Updated Daily at http://www.hallikainen.com >> Not sent from an iPhone. >> -- >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .