Try dropping PL on the tail. Could be a signal mixing with your repeater
offset and allowing your PL to keep your repeater receiver open. For
example: 442.000 transmit with 100Hz PL + 5Mhz signal = 447.000 with
100Hz PL.
Doesn't matter if you use PL or DPL - it still loops back in, and ham or
commercial - on UHF they both use 5Mhz split. I have a 1250Khz AM
station 1 mile from my site and its 4th harmonic is 5Mhz. Probably
mixing somewhere locally; less when its raining (rusty bolt theory).
I run PL decode and CSQ encode to keep this from happening, or split the
PL tones differently. Of course its probably not the AM stations' fault,
but as Joe said its better than listening to it.
Tony
On 06/29/2010 06:21 AM, Joe wrote:
It sounds like the squelch closes on your receiver when the signal
drops, is that correct? If so, that would eliminate the possibility of
the noise being the output of a repeater that has a tail timer. Can you
detect any tail timer at all? If I were to make a guess, it sounds like
a transmitter that is keying up with noise, such as an RF link for
something, and noise on the link input is keying up the transmitter.
Are you able to detect any PL tone in the noise that you hear? PL may
give you a clue as to the source of the signal. Can you DF the signal?
Is this in the ham band, or commercial freq? Does it happen more at
certain times of the day? Is it weather related?
A trick that I used was to set up a spectrum analyzer and watch 10-20Mhz
at a time. I would listen to the noise and look for another signal that
keys up at the same time. Very time consuming, but can be very
effective. It's a crap shoot, but it beats just sitting and listening
to the noise. Some ham rigs even offer a crude spectrum analyzer mode,
such as my Yaesu VX7-R HT. I've used the VX7-R to look for signals with
some success. (I had to read the manual to get the darn think out of
the SA mode!)
I used to do a lot of tracking down of interference. It helps to
analyze what is not causing the noise and don't always focus on what you
think it is. Eliminating what is not causing the interference many
times helps you focus in on what is really causing it.
Good luck and 73,
Joe, K1ike
On 6/29/2010 4:15 AM, gm7svk wrote:
> Hello,
>
> Loaded sample to files section.
> Has anyone encountered this sort of noise on a system or have a
suggestion as to what might be generating it? Proving difficult to
determine source.
>
> Thank you,
> Doug - GM7SVK
>
>
