[OZAPRS] 12.5 Narrowband radios for APRS

Dion Bramich vk7ybi at yahoo.com.au
Mon Apr 2 18:13:51 EST 2007


http://www.febo.com/packet/layer-one/transmit.html

On Mon, 02 Apr 2007 16:52:17 +1000, <vk3xci at aanet.com.au> wrote:

>
> No no!
> 2.5kHz is ideal!!!
> Generally speaking, for packet radio, less is more! Particularly if the
> signal is to be digipeated. More so if the TNC is an old tnc2 and the
> wireless an fm828. :)
>
> Whatever you do don't try to up the deviation by overdriving the audio
to
> rig.
>
> The rule of thumb is NEVER exceed 3kHz! The ideal is to set max dev at
> 3khz then back off the audio drive for 2.5
>
> Works for me!
>
> Norm VK3XCI
>
>
>
>> Hi
>> I have a Motorola GM950Plus which was programmed with some 144  
>> frequencies
>> and repeaters. I have not had much of a chance to use it. It is a
narrow
>> band (12.5 kHz) radio but receive always sounded reasonable and
>> "un-clipped"
>> when used on the 25 kHz channels.
>>
>> My question; do you think this radio with 2.5 kHz transmit deviation  
>> would
>> still be usable on APRS (metro and rural use)?
>>
>> I've asked the tech who is currently programming 145.175 if he could
>> increase the TX deviation and if there are any TX channel filters that
>> would
>> make this increase useless or detrimental to performance.
>>
>> Maybe I will just have to increase the AFSK driving audio and hope for

>> the
>> best.
>>
>> Has anyone had any experience in this regard?
>>
>> Thank you,
>> Nick
>> VK2NDA / KI4SIL
>> _______________________________________________
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>> Ozaprs at aprs.net.au
>> http://aprs.net.au/mailman/listinfo/ozaprs
>>
>
>
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> Ozaprs at aprs.net.au
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>
>



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