An effective fade reduction antenna is to have one vertical and one horizontal antenna. Due to changes in the ionosphere the signals can arrive with constantly changing polarisation.
Barry VK2AAB David Rowe wrote: > Hi Daniel, > > Yes I have wondered if a separate rx with separate antenna might help > get around fades. I imagine there needs to be a certain separation > (certain number of wavelengths) between the antennas. > > Some other ways to get that 6dB are coding gain (if FEC can be made to > work better) and lower Codec bit rates (if that doesn't make the > robustness worse). At the tx end higher average power (reducing PAPR > issues) would also help the link budget. > > Thanks, > > David > > On Tue, 2013-03-05 at 20:30 -0800, Daniel Mundall wrote: >> David, >> Amazing to see all the work that has gone into getting it where it is. >> Thinking about that 6db you are looking for, wouldn't it be possible >> to get that at some point with something like SoftRock with dual tx-rx >> chains (MIMO)? It may not be practical for the lower bands(antenna >> size), but when possible it may be one of the easiest ways to get that >> link budget and possibly even lower the tx power. >> I found some of the ideas here interesting >> http://www.sequans.com/pdf/SequansUplinkMIMOWP0608_v2.pdf >> It may not something for right now, but it looks like something with >> potential for the future. >> 73s >> Daniel >> >> >> Sent from Daniel's iPhone >> >> On Mar 5, 2013, at 12:09 PM, David Rowe <[email protected]> wrote: >> >> >>> Hello, >>> >>> I have just published a new blog post on making FreeDV robust over >>> HF >>> multipath channels: >>> >>> http://www.rowetel.com/blog/?p=2905 >>> >>> Thanks, >>> >>> David >>> >>> >>> >>> ------------------------------------------------------------------------------ >>> Everyone hates slow websites. So do we. >>> Make your web apps faster with AppDynamics >>> Download AppDynamics Lite for free today: >>> http://p.sf.net/sfu/appdyn_d2d_feb >>> _______________________________________________ >>> Freetel-codec2 mailing list >>> [email protected] >>> https://lists.sourceforge.net/lists/listinfo/freetel-codec2 >>> >> ------------------------------------------------------------------------------ >> Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester >> Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the >> endpoint security space. For insight on selecting the right partner to >> tackle endpoint security challenges, access the full report. >> http://p.sf.net/sfu/symantec-dev2dev >> _______________________________________________ Freetel-codec2 mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > > > > ------------------------------------------------------------------------------ > Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester > Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the > endpoint security space. For insight on selecting the right partner to > tackle endpoint security challenges, access the full report. > http://p.sf.net/sfu/symantec-dev2dev > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > ------------------------------------------------------------------------------ Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the endpoint security space. For insight on selecting the right partner to tackle endpoint security challenges, access the full report. http://p.sf.net/sfu/symantec-dev2dev _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
