[OZAPRS] 70cm APRS - was there a verdict?

[Andrew McDade]

Gday Darryl and others,

Ive done some very basic tests on 70cm at 1200bps. Using the same APRS
path
for 2m and 70cm , same beacon rate etc. I found that whilst mobile ( even
slightly mobile ) I would get a good packet hit once every 10 or more
transmissions.Pretty unusable really. However when stationary ( perfectly
stationary ) The successfull packet hits would get close to the 2m rate
ie.
90 percent plus. It'd be very interesting too see the success rate of
running the same tests at 9600 bps. So a desicion on a 70cm frequency
would
be great.

Regards .. Andrew


----- Original Message -----
From: "Darryl Smith" <Darryl at radio-active.net.au>
To: <ozaprs at marconi.ics.mq.edu.au>
Sent: Monday, November 10, 2003 6:10 AM
Subject: RE: [OZAPRS] 70cm APRS - was there a verdict?


> Actually I think that things will get worse with the 9600 baud on UHF.
The
> problem is that you are changing frequency as well as speed.
>
> Rayleigh Fading occurs more as you go up in frequency... I cannot
remember
> the exact relationship between fading and frequency, but at best it is
> linear meaning that there will be three times as much fading.
>
> 9600 is far more succeptable to this fading too... It would be good to
> compare the performance of the 1200 and 9600...
>
> Darryl
>
> ---------
> Darryl Smith, VK2TDS   POBox 169 Ingleburn NSW 2565 Australia
> Mobile Number 0412 929 634 [+61 4 12 929 634 International]
> www.radio-active.net.au - www.radio-active.net.au\tracking
>
>
> -----Original Message-----
> From: ozaprs-bounces at marconi.ics.mq.edu.au
> [mailto:ozaprs-bounces at marconi.ics.mq.edu.au] On Behalf Of Grant Willis
> (VK5ZWI)
> Sent: Sunday, 9 November 2003 11:51 PM
> To: ozaprs at marconi.ics.mq.edu.au
> Subject: [OZAPRS] 70cm APRS - was there a verdict?
>
> Hi Everyone,
>
> I am trying to find out if there was a verdict on what
> 70cm frequency should be used for APRS in VK. Also, in deciding
> this, was any thought given as to what baud-rate this frequency
> should run at?
>
> A couple of us in Adelaide are considering building a 9600 baud
> 70cm APRS WIDE digi and before I buy crystals, I would like some
> certainty on this. Currently I am considering 439.100, assuming
> that 439.175 is perhaps the 1200 baud channel? (and not wanting to
> co-habit with this).
>
> Also, why 9600 you might ask, well the Kenwood APRS ready radios
> can all do 9600, and 9600 will better cope with the more rapid
> mobile fading environment you find at 70cm. The lower incidences
> of mobile electrical noise on 70cm might help things as well
> when compared with 2m - esp with 9600 baud.
>
> Regards,
> Grant VK5ZWI
>
>
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