My receiver is a Morotola Mitrek (Converted mobile). My input freq is 447.3750
We have heard the interference correlate with their freq 452.9375 (hear the
signal coming through at the same time via a scanner on 452).
This morning it was pretty bad again- I stopped by with a spectrum analyzer-
the 452.9375 was definatly STRONG- but it looked clean. There were a few other
carriers near it, but only half or less in amplitude. Other potential
frequencies they may use (But we have not heard anything on a scanner, just on
452.9375) are:
> UHF Frequencies
> Frequencies on the same line can be paired for possible full duplex or
> repeater use. 452.9375 is a common EOT device frequency in Canada.
457.9375
> is a common EOT device frequency in the USA.
>
> 452.3250 / 457.3250
> 452.3750 / 457.3750
> 452.4250 / 457.4250
> 452.4750 / 457.4750
> 452.7750 / 457.7750
> 452.8250 / 457.8250
> 452.8750 / 457.8750
> 452.9000 / 457.9000
> 452.9125 / 457.9125 Telemetry
> 452.9250 / 457.9250 Remote Control/Remote Indicator
> 452.9375 / 457.9375 Telemetry/Remote Control/Remote Indicator
> 452.9500 / 457.9500 Remote Control/Remote Indicator
> 452.9625 / 457.9625 Telemetry/Remote Control/Remote Indicator
> [edit] New UHF narrowband splinter frequencies
> 452.90625 457.90625
> 452.91875 457.91875
> 452.93125 457.93125 Remote Control/Remote Indicator
> 452.94375 457.94375 Remote Control/Remote Indicator
> 452.95625 457.95625 Remote Control/Remote Indicator
> 452.96875 457.96875 Remote Control/Remote Indicator
I tuned up the extra can I have as best I could with the probes I have,
figuring something is better than nothing). I could get abour 30dB of isolation
through it with about 1db of loss on my RX freq. I put it in-line after the rx
cans on the duplexer and it seemed to have stopped the interference (at least
fot the 15 minutes I listened afterwards). We'll see if this does the trick. I
would like to install an Advanced Receiver Reasearch preamp I have sitting
waiting for it, but I need to get this interference resolved first.
I would like to leave talking to the Railroad as a last resort.
Thanks!!
Tom
W9SRV
Nate Duehr <[EMAIL PROTECTED]> wrote:
On May 23, 2007, at 8:48 PM, tgundo2003 wrote:
> 2. Has anyone had any problems with interference from the Railroad
> Locomotive Remote control and telemetry systems? They are on 452.XXXX
> and 457.XXXX. I have a UHF repeater near a railyard and they are
> clobbering the input at times.
When you say "clobbering the input" have you looked at this signal
with a spectrum analyzer? I doubt they're really on your input.
What is your receive frequency?
You're more likely fighting a mix with something else or they have
serious problems with that transmitter. If they're really on your
input, which I assume is at least 3-5 MHz away... they gotta fix that
if there's any reasonable amount of separation between you and them.
Would be best to know before you bug 'em, but if they're friendly --
they'll likely have the right test gear to find out what their
transmitter is doing... if anything.
What kind of radio is your receiver, are there any other high-power
transmitters in the area, and what frequency is your receiver on?
If their transmitter is on full-time, and it only "clobbers" you part-
time, it's a mix... with something else that's going on and off the
air... you need to find that signal and then do the math to see if
the mix makes sense... etc.
--
Nate Duehr, WY0X
Yahoo! Groups Links
---------------------------------
Park yourself in front of a world of choices in alternative vehicles.
Visit the Yahoo! Auto Green Center.
