If you have a choice of test bandwidths use the widest available. The
worst EMI frequency may not correspond to your channel frequ. on the
day yoy test it - just on the days you use it!
You really need to scan the whole band of concern with a requency step
less than the test receiver bandwidth.

RP


On 05/09/06, Zik Saleeba <zik@zikzak.net> wrote:
> As a hobbyist I don't think I can claim to be a "true EE engineer".
> Still, I'll do whatever it takes to get this thing working so it's a
> fascinating learning process all the way.
>
> I'm definitely going to try Richard's suggestion of using a handheld
> receiver to check for interference with the 900MHz telemetry
> transceiver's band. The other receiver in the plane is a standard
> 36MHz FM R/C receiver and since I don't have an audio receiver for
> that band to use for testing I may have to break into the R/C receiver
> as you suggest. Although I suspect the unit is so integrated that it
> may have no available RF or IF stage outputs. I'll have to dig around
> and have a look.
>
> Thanks everyone,
> Zik (VK3FZIK)
>
> On 9/5/06, Mike Singer <znatok@gmail.com> wrote:
> > Zik Saleeba wrote:
> > > Can I assume that if I use the layout shown in the data sheet that
> > > I'll be relatively safe from EMI?
> >
> > It depends on your definition of term "relatively".
> > Following some general recommendations does not necessarily solve a
> > particular problem. That's the point where EE technician differs from
> > true EE engineer.
> >
> > Seriously, I think, you should measure both signals on the reciver's
> > first stage output =96 the level of noise caused by switching regulator
> > and the level of useful signal.
> >
> > If you find that ratio unsafe:
> > -       try to diminish the noise;
> > -       try to enhance the useful signal;
> > -       try to shift the noise frequency from the signal frequency and
> > provide better frequency filters;
> > -       use better noise-tolerant algorithms;
> > -       etc
> >
> > Regards,
> > MS
> >
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