Yep, it is just not in the vehicle right now
because I am not working with that type of
systems at this time. Takes about a half day
to get it all back in there.
The 50 Mhz stuff also wreaks havoc on the
embeded vehicular computers, most of them
have a time base somewhere around 42Mhz which
is right in the middle of low band VHF. I
was doing work with a utility out in Louisiana
which was running some 110 watt mobile units in
the 42-43Mhz region. When we added mobile data
to the system they put the higher power radios
in some bucket trucks, as soon as they keyed
the transmitter the motor would shut down. The
on board computer was getting reset, the problem
was a cable that was just about exactly 1/4 wave
length from the computer to the controller, the
fix was to change the time base to a different
frequency as shielding the cable was not easy
due to having to pull a whole cable harness out.
Shield and ground, shield and ground, that is
the way to keep the noise out.
> -----Original Message-----
> From: Josh Tiner [mailto:jtiner@tampabay.rr.com]
> Sent: Monday, December 23, 2002 07:19 PM
> To: slug@nks.net
> Subject: Re: [SLUG] Mobile mp3 player?
>
>
> It would be interesting to find out if any of this holds
> true. Do you own
> the equipment to perform such an experiment?
>
> -jtiner
>
> ----- Original Message -----
> From: <wchast@utilpart.com>
> To: <slug@nks.net>
> Sent: Monday, December 23, 2002 5:40 PM
> Subject: RE: [SLUG] Mobile mp3 player?
>
>
> > 300 baud packets in the spectrum region between
> > about 28Mhz and 54Mhz, I think that the wiring
> > in most vehicles turns out to be nice 1/4 wave
> > lengths in that region, so you get good pick up
> > when a packet radio system in a vehicle happens
> > to send a few packets, when it is within a few
> > car lengths of the meganoise vehicle. The front
> > end of the amp effectively becomes a mixer and
> > extracts a crude reproduction of the packet wave
> > form and sends it to the amp which does what it
> > was designed to do, amplify it and ship it off
> > to the speakers, which get it as high as the amp
> > can deliver it, and the result is a loud 150Hz
> > roar just prior to the speakers giving out.
> >
> > The fix is of course good shielding and grounding
> > of the audio wiring, but I suspect that most of
> > these car audio shops do not know much about shields
> > or grounds, so getting rid of maganoise rap music
> > pest (the most common form of meganoise heard
> > around here) is not so hard to do. If you have
> > properly grounded and shielded all the cabling,
> > nothing should happen.
> >
> > I can even hear it with higher speed mobile data
> > equipment that is in the VHF and UHF region, and
> > running 1200 baud and up, and at those frequencies
> > most gear is only running from 15-30 watts, that
> > tells me the installation is substandard.
> >
> > There is one somewhere in my area that I can hear
> > going down the road at times from 4-5 blocks away.
> > I am just waiting for a chance to try it on him.
> >
> > To me that is no different than someone going down
> > the street leaning on their horn, besides I wonder
> > what kind of damage it is doing to the ears, brain
> > and whatever else is being subjected to that level
> > of audio inside a closed chamber.
> >
> > > -----Original Message-----
> > > From: Josh Tiner - DI Radio [mailto:jtiner@tampabay.rr.com]
> > > Sent: Monday, December 23, 2002 12:37 PM
> > > To: slug@nks.net
> > > Subject: Re: [SLUG] Mobile mp3 player?
> > >
> > >
> > > Run that one by me again and tell me what it does...
> > >
> > > -jtiner
> > >
> >
> >
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