[aprssig] How About 40M APRS (aka TONE PAIRS, Out-Of-Band etc)
shortsheep at worldnet.att.net
Tue Jun 3 03:42:28 CDT 2008
Well, the "indicated dial frequency" is a serious point of debate!
Depending on your particular radio, it may show one of several things.
You NEED TO READ YOUR MANUAL TO DETERMINE EXACTLY WHAT YOUR DIAL SHOWS!
For instance, in my FT-1000D, there is a switch, located underneath an
Access plate on top of the radio, that allows you to select several
different tone pairs. The switch position affects ONLY THE DISPLAYED
FREQUENCY, not the actual transmit frequency. If I recall, there are
Maybe 3 selections, 1600/1800/2100 to correspond to the various TNC's
Available that were popular at the time this radio was designed (KAM,
TAPR, AEA, they all have different tone pairs).
I believe there is even a switch position that DOESN'T SHOW OFFSET.
SO... your dial can show whatever the designer intended.
It doesn't necessarily show carrier frequency, or packet offset
WHO KNOWS??? Check how your radio is set up, and what the options are,
What your TNC tones are, and do the simple math. IF YOU SET YOUR RADIO
TO THE WRONG SETTING, NOT CONFORMING TO YOUR TNC'S ACTUAL TONE PAIR, THE
DIAL FREQ MAY BE TOTALLY WRONG, AND YOU'LL HAVE NO CLUE. Of course, for
This whole thing to work, you have to know exactly what YOUR tones pairs
And this affects your ability on most radios to transmit on 10.103MHz.
THE TRADITIONAL CONVENTION FOR DIGITAL MODES IS ALWAYS LSB.
But this has been lost because most modern radios automatically select
USB for upper bands. It may be necessary to adjust your operation to
USB and "tune down" to adjust for your tone pair if your radio's CPU
"thinks" it transmitting out of band. Or visa versa...
From: aprssig-bounces at lists.tapr.org
[mailto:aprssig-bounces at lists.tapr.org] On Behalf Of Dave Baxter
Sent: Tuesday, June 03, 2008 1:11 AM
To: TAPR APRS Mailing List
Subject: Re: [aprssig] How About 40M APRS
> The indicated "dial frequency" on SSB is the suppressed carrier
> The suppressed carrier frequency is NOT transmitted.
Point of technicality.... Your "Suppressed" carrier IS still
transmitted! Maybe (hopefully!!) many dB down on the wanted sideband
signals, but it is still there. If you have some 40dB suppression, &
many "Amateur" rigs when more than a few years old are not even that
good! Just tune around 40m or 80m on a Sunday and listen..
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