I saw those 10m sigs on my P3 screen this morning. There
would be some short bursts even down in the 27mhz chicken band.
Looks like an experiment of some kind rather than delierate
QRM. Whatever the source, it is trash and needs to stop.
73,
Charlie, N0TT
On Sat, 22 Feb 2014 12:39:01 -0500 "Karin Anne Johnson"
<karinann@tampabay.rr.com> writes:
> Hello Group:
> This is not so much an RFI issue, but more of a curiosity question.
> I've
> noticed for quite some time now that there appears to be what I
> would call
> sweeper signals that are quite strong on ten meters. Mostly in the
> CW
> sub-band.
> These signals start mostly around 28.200 MHz and sweep down in
> frequency
> stopping around 28.000 MHz. It is difficult to actually measure the
> exact
> start and stop frequencies as they sweep pretty fast. I'm looking
> at them
> with PowerSDR. The signal strengths vary, with most of them being
> about -80
> to -90 dBm. The antenna I am using is a simple ten meter dipole
> about 30
> feet in the air. I only see these signals during the day time when
> the
> band is open. I've never seen them after the band closes here in
> Florida
> after dusk. As usual I've powered off the entire house and they are
> still
> there on the spectrum display. Has anyone else seen these signals?
> What
> might they be? Ionsondes, Over the Horizon Radar of some type,
> Ocean
> mapping RF source? In the past I've found that Ionsondes usually
> sweep up
> in frequency, and
> cover a much broader range of frequencies. On a similar note, I've
> also
> seen what might best be described as wideband data bursts, lasting
> from 2 to
> 3 seconds on a range of frequencies just below ten meters. Between
> about
> 27.500 MHz and 28.000 MHz. Looking at these signals on the spectrum
> display
> it almost seems that there is a master/slave relationship between
> some of
> these data burst signals. As one stops sending it is observed
> another one
> starts sending. These also only observable during the daylight
> hours. I
> know that the 27 MHz band used to be allocated to ISM devices so
> maybe that
> is what these signals are related to. I know, too much time on my
> hands
> and a mystery to be solved. Can't resist the urge. Anyone
> interested in
> positing a guess?
>
> Regards,
> Karin Anne Johnson K3UU
> Palm Harbor, Florida
>
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