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[aprssig] Net28

G0JXN Jim g0jxn.jim at ntlworld.com
Tue Jun 15 15:51:20 UTC 2010


Hi Guys

Stephen, Richard and Dave, thank you for your input on the subject. I have 
taken note and www.net14.org.uk now has notes about LSB & USB working on 
both the Net28 Project and APRS Frequencies pages.

Incidentally we had 10m openings in Europe on the 12th & 13th June and 
excellent message exchanges between the UK, France, Germany and Belgium. 
Contacts were direct and first time ACKs were usual.

73

Jim, G0JXN/MB7UXN

> Date: Mon, 14 Jun 2010 13:55:51 +0100
> From: "Dave Baxter" <dave at uk-ar.co.uk>
> Subject: Re: [aprssig] Re Net28
> To: "TAPR APRS Mailing List" <aprssig at tapr.org>
> Message-ID:
> <FAD0F39D8FA7F440861941A74B1AE56044D269 at sbsserver.AREMV.local>
> Content-Type: text/plain; charset="us-ascii"
>
> Hi.
>
> The actual tone freq's from the TNC do not matter, be they 1600/1800 or
> 2100/2300, 2400/2600 or whatever, the shift is still 200Hz, the only
> reason you need to know them (what *Your* kit is using) is to adjust
> your radio's dial frequency, so the RF frequencies used are the same as
> everyone else.   Just because one person is using one set of tones, does
> not matter, so long as you know what yours are, to tune to the correct
> Dial freq' for the RF frequency used.
>
> It would make more sense to use USB on 10m, as others have said, most
> Ham kit will default to USB if they do not have a specific "data" mode,
> and much ex commercial (and some military) kit just will not do LSB at
> all.  (At least, often not without a lot of hassle.)
>
> Much digi mode computer software will do all that for you, so long as
> you tell it what the rig dial and sideband settings are, or you let the
> software control the radio.  Job done.
>
> I believe the convention used to be, to quote the 'Mark' state (idle)
> frequency as the reference freq' at RF, and if the shift was Up or Down
> for the 'Space' state.  (The RF frequency shift, not the Sideband mode.)
>
> In any case, I was under the (mistaken?) impression, that much of HF
> APRS used a PSK type modulation, where the USB/LSB problem does not
> exist, as it's the changes of phase that convey the information, not
> relying on discrete frequencies and shifts.
>
> Or did I skip something, again......
>
> 73.
>
> Dave G0WBX.




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