>From >http://go2.wordpress.com/?id=725X1342&site=rosmodem.wordpress.com&url=http%3A%2F%2Fwww.box.net%2Fshared%2Fq4e20pgnef
"ROS uses a Spread Spectrum technique known as Frequency-hopping spread spectrum (FHSS). In a conventional 16FSK system, the data symbols modulates a fixed frequency carrier; but in a FH/16FSK system, the data symbols modulates a carrier whose frequency pseudorandomly determined. In either case, a single tone is transmitted. ROS modulation scheme can be thought of as a two-step modulation process – data modulation and frequency hopping modulation—even thought it can be implemented as a single step whereby the frequency synthesizer produces a transmission tone based on the simultaneous dictates of the PN code and the data. At each frequency hop time a PN generator feeds the frequency synthesizer a frequency word (a sequence of l chips) which dictates one of 2^l symbol-set positions. The frequency hopping bandwidth, and the minimum frequency space between consecutive hops positions, dictate the minimum number of chips necessary in the frequency word. In the receiver, the received signal is first FH demodulated (dehopped) by mixing it with the same sequence of pseudorandomly selected fre1quency tones that was used for hopping. Then the dehopped signal is applied to a conventional bank of M noncoherent energy detectors to select the most likely symbol." Andy K3UK ------------------------------------ Try Hamspots, PSKreporter, and K3UK Sked Page http://www.obriensweb.com/skedpskr4.html Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) <*> To change settings via email: digitalradio-dig...@yahoogroups.com digitalradio-fullfeatu...@yahoogroups.com <*> To unsubscribe from this group, send an email to: digitalradio-unsubscr...@yahoogroups.com <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
