Hello Andy, > software application "has to see" before it starts printing out text ? In general for the common modes, as PSK31, RTTY, the decoding is permanent. If you don't use Squelch, you will be have random characters in absence of signal.
Some modes as Packet, Pax, Pax2, Pactor1 needs some flags to initiate the reception and, in all cases, a control by check sum is done at the end of the frame, so only the valid frames are displayed. There are no random characters. > the software have to have a combination of tones it recognizes that > equals the code for characters in the alphabet? It depends of the modulation. The scheme you described would applie to ThrobX (combination of two tones). >When AFC is on and the software "looks" for a signal to lock on, what does >it need to >see for it to lock on ? There is no selection either. The AFC is always working. The way it works depends on the mode (FSK, MFSK, PSK). In PSK, the Costas loop converges, as a PLL, to the phase which renders the Q term (quadrature phase term) nil (or the real term (I) maximum). In FSK, it's a measure of the strongest carrier.... 73 Patrick ----- Original Message ----- From: "Andrew O'Brien" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Tuesday, March 21, 2006 1:52 PM Subject: [digitalradio] Dumb question of the day > Maybe it is obvious to most , but.... > > I was watching the tuning indicator in PC ALE and also looking at the > waterfall in Multipsk and began to wonder about what a digital > software application "has to see" before it starts printing out text ? > Is it just the correct width of a signal , a mark/space issue ? Does > the software have to have a combination of tones it recognizes that > equals the code for characters in the alphabet? When AFC is on and > the software "looks" for a signal to lock on, what does it need to see > for it to lock on ? > > > > -- > Andy K3UK > Fredonia, New York. > Skype Me : callto://andyobrien73 > Also available via Echolink > > > Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org > > Other areas of interest: > > The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ > DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy > discussion) > > > Yahoo! Groups Links > > > > > > > Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
