Thanks for the explanation Eddie. Another advantage of trunking. My
thoughts were thinking about a conventional digital system such as in
use by smaller agencies. In my rural county, I am not aware of any
trunking for city/county public service except the state agencies. I am
near certain police, sheriff, EMS (still VHF analog), hospital to
hospital are not trunking. Even the power co itself which is only about
1/2 mile from me.
The power line rfi i have now started by pulsing in a roughly
distinctive pattern which I could hear easily on the AM car radio. I
drove around and could hear it for roughly a 1.5 mile radius which would
be within range easily of the power co's 100' + tower I would think even
though they are on VHF and their system is now conventional digital as
far as I know. So its probably de sensing them.
I rarely get this lucky but the pole I think its emanating from, after
much tracking, is already marked to be replaced due to a weak pole. I am
in waiting mode now to see before I track further.
73
Chuck
AF4O
On 11/26/19 9:09 AM, EDWARDS, EDDIE J wrote:
Chuck,
It probably depends on the agency and if they have in-house technicians or if
they outsource tech support whether they can respond to and track down an
interfering source right away or not. But the trunking systems will alarm if a
channel is getting interference and will remove a channel from service if the
interference is chronic or sustained.
Our experience with our 800Mhz ORION-shared, trunked radio system in Nebraska
is if the system controller doesn't remove a channel from service right away,
then the public safety radio subsystems may notice coverage degradation earlier
than our utility does since their sites are designed for indoor portable radio
coverage while our utility only has mobile radio coverage on our subsystem.
Old cellular boosters are the usual culprit that gets into an 800Mhz radio
system causing a channel to alarm and then be removed from service by the
controller.
Radio users will not notice anything most of the time since a chronically bad
channel won't be assigned to the users of a trunked radio system.
Back during the analog days, we've had local TV and radio studio links' with
bad harmonics drift into the 800Mhz band, but those were easy to identify and
find since the broadcast ID made it clear who it was. Those would be harder to
locate in today's digital world unless you use a multi-digital mode receiver
like in certain test sets/monitors.
73, de ed -K0iL
Eddie Edwards
-----Original Message-----
From: RFI <rfi-bounces@contesting.com> On Behalf Of Charles Plunk
Sent: Sunday, November 24, 2019 6:53 PM
To: rfi@contesting.com
Subject: Re: [RFI] FCC Complaint Filing
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You guys that are more familiar with public service digital systems
(fire police EMS etc) than me maybe can enlighten me. Would these
sources of RFI that we track for our ham analog systems not interfere
with digital systems? But maybe go unnoticed since the users of the
digital may not even notice since the RFI just de-senses the digital
system to where the range is limited but what does go through is still
clear? And that limited range could affect vital communications?
That to me makes us tracking down interference immensely important does
it not? Its like we are doing a free public service. And the FCC should
back us up, if by just stern letters, for this reason if not for
ourselves (which they should).
Just a thought.
Chuck
AF4O
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