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[aprssig] APRS Databusrt

Dave Baxter dave at emv.co.uk
Tue Aug 14 10:04:32 UTC 2007

> On both in/out frequencies to the repeaters we have the 
> biggest trouble for here trucks with cranes or other cars 
> with the need of remote controls and yes they are active a 
> full work day i.e 0600-1600 and if thers something been 
> buildt it's also used after this time.

I never liked the idea of radio controlled cranes, winches etc on
vehicles.   I guess the crane controls (being far more functional and
expensive "professional" devices) probably fail-safe in the presence of
a strong "spurious" signal as they se it, just being a major
inconvenience when the thing stop's with your load in mid air?

Some of the 4x4 winch models with remote radio links as an option I'm
less than impressed with.  I've not seen one fail and continue to pull,
but as many of these are in "Consumer" hands (4x4 enthusiasts) who do
not understand these things, it's only a matter of time perhaps before
someone gets hurt while using one of these, and someone else nearby to
it is also using a licence free voice hand-held...   They shouldn't
interact, but????

I have seen a 27MHz CB open a garage door though!  Harmonics?   And
there is at least one documented case in the UK where a 432MHz CW
operator, had "side tone" from a nearby wireless home security system!..

When I get to bolt a winch to my Land Rover (if I ever do) it'll only
have wired controls, ever!....

In the days of connected Packet (early 90's) in the UK, a neighbour of
mine at the time complained to me once that her new home alarm the kept
going off every 15 minutes, when it was armed!  (A new install I found)
And did I know anything about alarm systems?  (She knew I worked with
electronics etc)

I was sending a packet ID burst at that interval (10W to a roof space J
pole) being in a rented house, no external antennas could be seen, only
those on the afore mentioned Land Rover parked up between our houses,
that were inactive...   I said nothing of course.  She got it fixed a
few days later, but the installer had to change each and every PIR
sensor, especially as it got worse one day, every 5 minutes...  Cant say
how that happened...  ;-)

Take care with high power mobile trackers, especially round construction
sites etc, you never know these days what crappy UHF super-re-gen RX
might be in control of some plant or machinery, or what your actual
radiated 3rd harmonic level is...


Dave G0WBX.
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