Hello Jose,
Thank you for addressing my questions. I am not going to order that book, even I could find a copy. And I do not live close enough to libraries carrying it. We need a "SS for Dummies". In any case, thank you for addressing the question. Kind Regards, Rein W6SZ -----Original Message----- >From: "Jose A. Amador" <ama...@electrica.cujae.edu.cu> >Sent: Mar 6, 2010 6:37 AM >To: Rein A <rein...@ix.netcom.com> >Cc: digitalradio <digitalradio@yahoogroups.com> >Subject: Re: [digitalradio] Re: ARRL/FCC Announcement about ROS > >El 06/03/2010 4:49, rein...@ix.netcom.com escribió: >> I thought, that there has to be a direct specific connection >> between the transmitter and the receiver on how to retrieve >> the "info" from the spread spectrum. ( SS for dummies ) >> >> This makes it useful for the militairy, for who it was >> originally designed and in the case of cell phones, for >> instance, the code recovery algorithm is programmmed in >> the system, not secret, I assume, but still hard to figure. >> I thought cell phones run over 1,5 Mhz wide spreading. >> >> Is this true? I for one have never thought or learned >> much about SS. ( 75 yrs and retired and I am sure some >> will say you know what ) >> >> 3000 Hz info band -> 1.5 10 e+6,Hz ? >> >> Anyway what is so frustrating to me here, is that I do not >> see a straight definition of SS written in a published book >> that I can cross reference. >> > >Carlson, Bruce, Communications Systems, Chapter 15 Spread Spectrum >Systems, p 671, Mc Graw Hill 2002 > >> I have the ARRL SS source book, and there, all I can find is >> that SS spreads the "info band" width between 10 and 100 times. >> >> Also I thought if one looks with a Spectrum Analyzer,( I have >> never done that, ) to a SS signal, is is hard to see the side bands. >> Signals so weak and so random, perhaps semi- that one can >> have a large number of those side bands from different transmitters >> overlapping without causing problems in the communication >> process. >> > >It should be that way. But ROS has insignificant spreading when compared >to what has become publicly known about SS (i.e., 802.11). > >> Just a INCREASED noise level, that would seriously be a problem >> for EME, for instance, it would cover up the natural background >> or with other words, increase the noise temperature, >> >> Now here you have a few simple concepts, it is crazy talk >> yes or no? Please feel free to tell your views with a >> basis, where I can look it up myself. >> I asked before for a peer reviewed paper "SS for laypersons >> or dummies" >> >> I do only WSJT on HF and on EME as group member, please someone explain >> to me why WSJT is, what? >JT65A is MFSK with a heavy block coding scheme and high redundancy. It >is NOT spread spectrum. > >> It appears to be legal? >> > >Yes, it is NOT SS and occupies some 170 Hz. It is WELL DOCUMENTED by Dr. >Joseph Taylor, K1JT, a Nobel Prize Laureate and Princeton Professor. > >> What is the difference between JT65C and ROS when it relates >> to the SPREAD Spectrum properties, >> > >Apples and oranges. ROS does not quite reach the level of >sophistication of WSJT, within the bounds allowed to hams in the US. > >> WSJT has a smart and efficient info packing scheme that makes >> it pretty much an all or nothing system. ROS, produces >> a lot of errors, if the signal strenght goes down after >> the start, but that is not a SS issue, >> >Certainly not. ROS is a baby compared to JT65 robustness. >> Please explain to me and perhaps quite a few others what >> SS is, other than that is "Wide" Im my own mind the width >> has not really too much to do with it? True or false. >> >Ideally, SS should be of infinite bandwidth, which is not viable in >practice. As you reduce it to a practical, allowable level, its "magic >properties" >lose strenght, be it direct sequence or frequency hopping. >Theoretically, FH should have a very small dwell time, but then again, >to contain at least 90% of the spread message sidebands in a 3 kHz >bandwidth makes it "not undescernible from noise". >> All straight layman's questions, so who answers them, most of us >> like to learn and understand a little. >> >> 73 Rein W6SZ >> > >73, > >Jose, CO2JA > > > > > >------------------------------------ > >Try Hamspots, PSKreporter, and K3UK Sked Page >http://www.obriensweb.com/skedpskr4.html >Suggesting calling frequencies: Modes <500Hz 3583,7073,14073,18103, >21073,24923, 28123 . Wider modes e.g. Olivia 32/1000, ROS16, ALE: 14109.7088. >Yahoo! Groups Links > > >
