Rick, Thanks for that explanation. I knew there was an historic reason. I will file your explanation away for further reference. As long as we remember that the mark is the carrier and that space is shifted down in frequency, we should be in good shape no matter whether we use FSK or AFSK USB or AFSK LSB. With the m-ary FSK and multi carrier PSK modes we have lost the concept of mark and space. I was discussing that in another thread on QRZ.com.
73, Mark N5RFX At 02:07 PM 10/23/2005, you wrote: >Mark, > >In the "old" days you would use a CW transmitter for RTTY. Then you would >pull the signal down for the shift by having a capacitor across the VFO, >thus producing an FSK signal. The operating frequency was always the mark >frequency. The mark frequency was high and the space frequency was always >low since you pull the frequency lower when you add capacitance. > >When AFSK was developed to inject tones into the rig to simulate pulling >the VFO down, the mark tone was the lower frequency and the space tone was >the higher frequency so it would be compatible with existing FSK >operation. Remember that by using LSB, a higher audio tone would translate >into a lower transmitted frequency so the higher space tone became a lower >transmitted frequency. This kept the mark high for the transmitted >frequency even though the audio frequency was the reverse with the space >tone high. > >With today's technology, it is not necessary to do this and everything in >the military and commercial HF bands is pretty much USB only. So the trend >is to just make everything USB and it makes it a lot less confusing as you >say because you add the tones instead of subtracting them. > >73, > >Rick, KV9U > > > > > > > > > > -----Original Message----- >From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] >Behalf Of Mark Miller >Sent: Sunday, October 23, 2005 12:26 >To: digitalradio@yahoogroups.com >Subject: Re: [digitalradio] WHY ? ? ? > >John, > >It really doesn't matter which SB you use with most sound card >programs. If the mode is sensitive to polarity, then there is usually a >reverse or inverse switch. The only difference will be the dial frequency >on your rig, but the actual operating frequency will be the same whether >you use LSB or USB. I was trying to remember why RTTY was LSB. I seem to >remember it had something to do with modifying VFOs in the early 50's? I >don't remember. USB is more comfortable for me, it seems I can add the >audio tones to the dial frequency easier than I can subtract them. > >73, > >Mark N5RFX > >At 10:45 AM 10/23/2005, you wrote: > >Can some one tell me why the sound card digital modes use USB > >and not LSB like the other digital modes? > > > >John, WØJAB > >Louisiana, Missouri > >EM48LK > > > > > > > > > > > > > > > > > >The K3UK DIGITAL MODES SPOTTING CLUSTER AT telnet://208.15.25.196/ > >More info at > <<http:///www.obriensweb.com>http:///www.obriensweb.com>http:///www.obriensweb.com > > > > > > > > > >SPONSORED LINKS > ><<http://groups.yahoo.com/gads?t=ms&k=Craft+hobby&w1=Craft+hobby&w2=Hobby > +and+craft+supply&w3=Ham+radio&c=3&s=60&.sig=YqiuyVwjnQFdynnsmMwVWg>http://groups.yahoo.com/gads?t=ms&k=Craft+hobby&w1=Craft+hobby&w2=Hobby+and+craft+supply&w3=Ham+radio&c=3&s=60&.sig=YqiuyVwjnQFdynnsmMwVWg>Craft > > > >hobby > ><<http://groups.yahoo.com/gads?t=ms&k=Hobby+and+craft+supply&w1=Craft+hob > by&w2=Hobby+and+craft+supply&w3=Ham+radio&c=3&s=60&.sig=VduRJqNqUo9QkUiTI-knAA>http://groups.yahoo.com/gads?t=ms&k=Hobby+and+craft+supply&w1=Craft+hobby&w2=Hobby+and+craft+supply&w3=Ham+radio&c=3&s=60&.sig=VduRJqNqUo9QkUiTI-knAA>Hobby > > > >and craft supply > ><<http://groups.yahoo.com/gads?t=ms&k=Ham+radio&w1=Craft+hobby&w2=Hobby+a > nd+craft+supply&w3=Ham+radio&c=3&s=60&.sig=sl_TRqZTiP_WHSLe6P3ybA>http://groups.yahoo.com/gads?t=ms&k=Ham+radio&w1=Craft+hobby&w2=Hobby+and+craft+supply&w3=Ham+radio&c=3&s=60&.sig=sl_TRqZTiP_WHSLe6P3ybA>Ham > > > >radio > > > > > >---------- > >YAHOO! GROUPS LINKS > > > > * Visit your group > > > "<<http://groups.yahoo.com/group/digitalradio>http://groups.yahoo.com/group/digitalradio>digitalradio" > > on the web. > > * > > * To unsubscribe from this group, send an email to: > > * > > > <mailto:[EMAIL PROTECTED]>[EMAIL PROTECTED] > > > > > * > > * Your use of Yahoo! Groups is subject to the > > > <<http://docs.yahoo.com/info/terms/>http://docs.yahoo.com/info/terms/>Yahoo! > Terms of Service. > > > > > >---------- > > > > >The K3UK DIGITAL MODES SPOTTING CLUSTER AT telnet://208.15.25.196/ >More info at <http:///www.obriensweb.com>http:///www.obriensweb.com > > > > >---------- >YAHOO! GROUPS LINKS > > Visit your group > "<http://groups.yahoo.com/group/digitalradio>digitalradio" on the web. > > To unsubscribe from this group, send an email to: > ><mailto:[EMAIL PROTECTED]>[EMAIL PROTECTED] > > > Your use of Yahoo! Groups is subject to the > <http://docs.yahoo.com/info/terms/>Yahoo! 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