Interference can be a difficult thing to find, I do this at work
quite often. Let's see what we have so far:
1) The Motorola Nucleus 900 Mhz paging transmitter has a hisotru of
the PA creating broadband noise. You do not have broadband noise,
you have two signals 20Khz wide at 144.510 and 154.490Mhz.
2) The signals are 20Khz wide. The 900Mhz paging signal should be
9Khz wide, so the signal you are seeing is twice the modulation width
of the fundamental transmitte signal. Usually a sign of 2nd harmonic
intermodulation. I kind of doubt that. Can you hear anything on the
signal? This is important to know.
3) The two signals you saw are 9.98Mhz apart. Almost 10Mhz, or it
could be 10Mhz depending how you read the spectrum analyzer. This is
telling us someting, but I don't know what.
4) You saw the 144.51Mhz signal on the spectrum analyzer and hear it
on the repeater receiver. This tells me that it probably is not
being generated in the repeater receiver. I doubt if the spectrum
analyzer and receiver share the same IF and local oscillator
frequencies.
5) Your considering filing a complaint against a paying customer on
the site. I hope that you are also a paying customer (or own the
site) or you are subject to be asked to leave. This happens, even if
you are right.
6) Motorola sold off their paging infrastructure business several
years ago. That's why they will not answer your questions.
7) The problem happened when they moved their antenna? Maybe they
also changed frequencies. I wonder why the moved? Moving antennas
is expensive, there must be some reason that they did it.
Maybe someone else has some ideas to add.
joe
--- In Repeater-Builder@yahoogroups.com, "Coy Hilton" <[EMAIL PROTECTED]>
wrote:
> AS stated in one of my posts, it's 144.510 MHZ. the remainder of
the
> equipment used to assist with eliminating this problem is as
> follows. a Wacom WP641 duplexer, BpBr With an Additional BAnd
Pass
> cavity tuned to my receive frequency, also a Notch filter, a 5 pole
> Helical front end feeding a MASTRII receiver with additional 5
poles
> Helical filtration. Please read the following carefully and slowly.
> THE INTERFERANCE IS ON THE RECEIVER FREQUENCY...I CAN SEE IT ON THE
> SPECTRUM ANALYZER and AT LEAST ONE OTHER PLACE ON THE BAND AT
> 154.490, BROAD BAND, AND 20 KHZ WIDE.
>
> This problem has to be solved at the source not band aided by me
> trying to put every kind of filter known to man on my receiver. The
> only way that I can solve it, is to move to another site or turn my
> receiver off. What I need to know is has anyone had this problem
> with this Transmitter and a little about the transmitter like
normal
> configuration.
>
> Oh, Motorola told me that They didn't build this model
> transmitter. " It was built by Nucleus Inc a third party company in
> Texas"
>
> It's difficult to get 40 feet vertical seperation on top of a
> building.
>
>
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