Re: Micro controllers with UHF transceivers?

JosephKK wrote:
Joerg notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx posted to
sci.electronics.design:

Paul Keinanen wrote:
On Wed, 24 Oct 2007 13:34:29 -0700, Joerg
<notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote:

Hello Folks,

After some Google searching and perusing the sites of the usual
contenders I only found one uC family that has serious on-chip RF
transceiver capabilities, the Cypress CYWUSB6953 and its brethren.
rfPICs and others usually only have a transmitter.

Anyhow, the Cypress will only serve 2.45GHz but I need the lower
UHF bands for range reasons. Is anything coming down the pike soon
or will that have to remain a two-chip solution?
It would help if you had specified the country in which it should
operate. The frequency bands, the power levels and duty cycles vary
with country or at least with continent.

As many countries as possible. Definitely US, Canada, Europe and in
and around the Gulf of Mexico, other cases also Asia. That leaves
433MHz and 2.45GHz. Or frequencies below 100MHz but there aren't any
integrated solutions for those.


You said that the range was too short on 2.45 GHz. What kind of
propagation environment do you have ? Free space, lot of thick
trees, indoor or what ?

All of the above, usually comms between a pod inside the house to
equipment outside. I guess our house would be the worst case,
woodframe construction with aluminum backed insulation inside the
walls.


In a free space environment, the capture area of an omnidirectional
receiver antenna at a higher frequency can get quite small, thus
the receiver signal will be weaker. Also a lot of wet trees will
attenuate the 2.45 GHz signal.

On the other hand, in typical indoor situations and at the streets
of a large city, there are going to be plenty of reflections and
the propagation is more or less independent of the frequency. The
shorter wavelength might even propagate more easily through narrow
slits in air conditioning ducts etc.

All I can say that around our house 2.45GHz does not work reliably
at all. <200MHz works excellent.


Now you are talking VHF instead of UHF.


Yes, my dream would always be VHF for this stuff. Unfortunately no chips and the countries on this planet haven't come to agreements there.

--
Regards, Joerg

http://www.analogconsultants.com/
.

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