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[aprssig] APRS Bandwidth

Dave Baxter dave at uk-ar.co.uk
Mon Jun 29 14:19:41 UTC 2009


Hi Jim (and listners)

The ALE people will welcome all users, EMCOM or otherwise.  After all,
the more there are, the more usefull the network can be if needed in
anger.

You can also run ALE in listen only mode, if you don't want to tread on
peoples toes.

I like the phrase "break in" a new computer.  Strangely approprite I
feel in many cases. 

Cheers..

Dave B G0WBX (just in from a very hot White Van Man jaunt on the M1.
30+'C outside temperature, and no air con!  With the added stress of
extreme "Muppet Mainia" in regard to some peoples driving.)


> -----Original Message-----
> From: G0JXN Jim [mailto:g0jxn.jim at ntlworld.com] 
> Sent: 26 June 2009 22:28
> To: aprssig tapr
> Subject: [aprssig] APRS Bandwidth
> 
> Hi Guys
> 
> Dave
> 
> I am trying to break in a new computer so have not had the 
> time to go through the web site you have suggested. I will do 
> so in due course but am always a bit nervous of treading 
> where the emergency guys hang out.
> 
> > Message: 1
> > Date: Thu, 25 Jun 2009 14:23:14 +0100
> > From: "Dave Baxter" <dave at uk-ar.co.uk>
> > Subject: Re: [aprssig] APRS-SIG (... proposal for a world wide APRS 
> > net on 20m?)
> > To: <g0jxn.jim at ntlworld.com>, <aprssig at tapr.org>
> > Message-ID:
> > <FAD0F39D8FA7F440861941A74B1AE5602FCF75 at sbsserver.AREMV.local>
> > Content-Type: text/plain; charset="US-ASCII"
> >
> > Hi Jim (and others)...
> >
> > There is already ALE or HFN.  A world wide automated HF digital 
> > messaging system, primarily for emergency use, it's there 
> and working.
> > With the ability to negotiate a link for voice too (SSB)
> >
> > http://www.hflink.com/  It also has some APRS like position 
> reporting 
> > facilities.
> >
> > However, our licence limitations don't make that mode easy 
> to deploy 
> > either, hence the lack of G (or M) stations active in this mode.
> >
> >
> > 20m is congested enough as it is on most weekends (contests 
> etc.)  I 
> > suspect a proliferation of APRS would not exactly be 
> welcome, even if 
> > a compatible slot for it could be found.
> 
> In Europe 30m is a lost cause it's not stations that digi in 
> band it's those stations crossbanding from 2m. Apart having 
> the view that Igates are not real radio I don't have enough 
> years to make any changes to 30m in Europe.
> 
> > I understand your concerns re 30m APRS, and it is useful on 
> occasions.
> > However, the problem with digi's is they dramatically increase the 
> > loading on a single channel of course, and at 300bd, that's 
> already 4 
> > times as long (timewise) for a typical packet as at VHF.  
> Unless there 
> > could be some (internet based?) liaison between any such 
> digis so that 
> > one and only one digi'd what was heard.
> >
> > But then, what happens when the i'net liaison link dies for 
> whatever 
> > reason.
> >
> > 30m iGates:  If correctly setup, so as not to spew stuff out to RF, 
> > only messages to those in direct earshot, maybe, and only 
> maybe that 
> > could work.  But again reliance on a service that we have 
> no control 
> > of in the background.  The Inernet (not the APRS-IS) of course.
> >
> > Then there is that old chestnut, that FSK is not exactly spectrum 
> > efficient these days, compared to other choices of digital 
> modulation 
> > available to us.
> >
> > Dave G0WBX.   Stirring it as usual.
> >
> > 73.



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