Wow!  I wish we had as relaxed regulations as you guys have over there
in NZ!  (I'm in the US.)  Here the only legal way to do it would be with
either a ham license (and even then I doubt it would fall under correct
usage) or an extremely expensive 1W (maximum allowed by law, at least on
ISM bands) spread spectrum (about 20 mile range, LOS; I've priced them
at about $350 for each transceiver).

> -----Original Message-----
> From: adam-request@viratech.com [mailto:adam-request@viratech.com] On
> Behalf Of Jinx
> Sent: Wednesday, June 26, 2002 6:33 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE]: Data transmitter
>
> > > Any suggestions or recommendations for transmitting data 5km to
10km ?
> >
> > Audio modulation into a PRS CB would probably work
>
> > DSE has a small PRS unit for $100 ish that would do the job
>
> www.dse.co.nz
>
> D1742 (Uniden UH037) is $99, 500mW, 3km line of sight
> D1760 (Uniden UH050XR) is $469, 1W/5W, no range given,
> but presumably >> than 3km
>
> The D1760 at 1W would do the 5km range. 5W would definitely
> cover 10km. Looking at the pictures the aerials seem acceptable
> Get rid of everything except the transmitter and we're in business
>
> > An FX604 modem IC would do the job (see me for cct) or almost
> > anything else at all
>
> This one ?
>
> http://www.cmlmicro.com/products/Datasheets/Docs/fx604ds.pdf
>
> > 0.3 x 8765 hrs =~ 3000 mAH/year.
> > Alkaline C cells would do this
>
> Yup, given the duty cycle I didn't think there'll be too much of
> a problem with batteries. Consumption will be a little more as
> I planned on 3 repetitive transmissions for reliability
>
> > > - Aerial acceptable only if short, stubby, robust etc
> >
> > Ah - maybe more info needed - if a Yagi at far end OK then can still
> work
>
> How big would the receiving aerial need to be if picking up a 5W
> transmission from 10km ? There are some limitiations because the
> receiver will be hand-held
>
> > > - Receive capability not needed
> >
> > You're not going to receive the data you send ? :-)
>
> No. Part of the brief is, I quote, "waste as much of Joe's time on
> this, all for no result, and then disappear without paying". Clot
>
> > > Apart from the tx, everything else is pretty much sorted. A couple
of
> > > days ago someone mentioned the 340 as a better choice for a very
> > > low-power sleeping micro. Is that true it's better than the PIC ?
> >
> > Yes. Can be very very very low
>
> I got some pdfs on the 430. Considering what else is in the circuit,
> sub-uA looks achievable. At a glance TI appear to have some free
> low-end dev tools that would get me started. I'm reluctant to take on
> yet another learning curve, but if duty calls...............
>
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