[aprssig] APRS Bandwidth

Chris Moulding chrism at crosscountrywireless.net
Tue Jun 23 06:55:45 CDT 2009

Hi Jim,

One way to calculate the bandwidth of an FSK transmission is the use of 
Carson's Rule.

Try Googling "Carson's Rule" and work through the mathematics.

It should provide sufficient proof for OFCOM.

By the way I had a hit on my website from OFCOM yesterday Googling for 
30m APRS. Have you enquired already?


Chris, G4HYG

Chris Moulding
Cross Country Wireless (2009) Ltd
7 Thirlmere Grove, Bolton, Lancs, BL4 0QB, UK
Tel/fax: +44(0)1204 410626
Mobile:  +44(0)7752 391908
Website: http://www.crosscountrywireless.net
Company number 6780346 registered in England and Wales  

G0JXN Jim wrote:
> Hi Guys
> The UK Amateur Radio license no longer allows the operation of an 
> APRS digipeater without special permission (Notice of Variation) from 
> the regulator (Ofcom). It being filtered first through the RSGB.
> I wish to run a digipeater on 10.151MHz (KAM) but am advised the it 
> would probably not be recommended by the RSGB because the bandwidth of 
> 300bd would exceed the 500Hz laid down in the IARU bandplan for 30m. 
> The implication being that we should not operate APRS on 30m at all.
> Monitoring signals on 30m I find that they all seem to be within 400Hz 
> but I will need to prove that on paper.
> Can anyone please tell me what the bandwidth will be for a properly 
> adjusted 300bd station and how this might be calculated?
> 73
> Jim, G0JXN
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