Those annoying "sweeping" sounds...

[Fansome]

From:   [email protected] on behalf of Jan Olof Bergstén ([email protected])
Sent:   Tue 8/03/10 3:22 PM
To:    [email protected]
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HI
 
These are Ionosonds
 
Most sweep from 2 MHz to 30 MHz with 100 KHz/s, some with 125 KHz/s and a
few with 500 KHz/s.
They often mute on the emergency channels, and frequencies used at nearby rx
sites.
 
Some make a sweep every 15 minutes, a few every 5 minutes, and also other
periods.
 
There are window programs availible to receive them and make your own
Ionograms, or to just identify them.
You can identify them if you note the frequency and time (to the nearest
second) as most start at fixed times.
 
I have an homebuilt sweep receiver that is locked onto the transmitters and
makes high quality Ionograms.
 
There is a special list for those interested in receiving this kind of
transmissions (moderator G3PLX).
 
More information at http://jcoppens.com/radio/prop/g3plx/index.en.php
 
73 Jan SM7ETW
 
 
On Tue, Aug 3, 2010 at 8:51 PM, vbifyz <[email protected]> wrote:
 
> I'm sure everybody here heard these annoying "chirps" many times, like
> somebody quickly turns the dial of the transmitter.
> When looking at them on a 192kHz SDR watefall, I can tell that these are
> really very wide sweeps. They happen once every few minutes on any band
> between 4 and 18 MHz. I think broadcast bands are excluded, I don't remember
> hearing quick short heterodynes when listening to SW broadcast stations. The
> sweep rate is about 200kHz/sec (the whole bandwidth of my SDR is sweeped in
> about 1s, maybe faster). The direction is always up.

[SW-J]

Yup; was on their e-mail list for several years.

There is also another purpose of those sweeps, as part of HF-DF SSL (Single-Site Location) systems ...

HF transmitter SSL (single site location) with combined ionospheric update - http://cat.inist.fr/?aModele=afficheN&cpsidt=2730955

APPLICATION OF IONOSPHERIC TOMOGRAPHY TO SINGLE SITE LOCATION RANGE EASTIMATION - http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.44.505&rep=rep1&type=pdf

Google search for same: http://www.google.com/search?hl=en&client=opera&hs=kMO&rls=en&q=HF+DF+SSL+%28single+site+location%29&aq=f&aqi=&aql=&oq=&gs_rfai=

[cmradio]

What a cool set of links guys, thanks!

6215.0      (carrier) Distress and Safety (GMDSS)

How DARE they put a distress channel on a popular EU pirate frequency

 

Peace!

[Fansome]

From:   [email protected] on behalf of Mike ([email protected])
Sent:   Tue 8/03/10 11:03 PM
To:    [email protected]
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Do a cut and paste into Google Earth with these coordinates:
37.565343,-77.024615  This will put you right on top of the transmitter at
Whitehouse, VA. Look closely and you'll see the antenna farm. It's changed a
bit since I last saw it.
 
 
Mike C.
 
(sandbar west FL)


 Facility 406 DM09
To [email protected]
From:   [email protected] on behalf of Facility 406 DM09 ([email protected])
Sent:   Wed 8/04/10 1:02 AM
To:    [email protected]
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"Ionosonde is not exclusive to balloon carried devices and is a term equally
applicable to HF propagation measuring devices."
 
Actually, the specific term has been erroneously applied to Ionospheric
Sounders, called such since the early-1920's when they were developed.  Many
years ago, some twit mis-identified and mis-translated "sonde" with "sound"
in this application and those that didn't know better, continue it to this
day.
 
Scientific and Military references from the start correctly identify
Ionospheric Sounding as such and balloon borne generic Ionosondes, only
known by this term, are rarely used having been replaced by more
discriminatory radiation detection/identification devices used as often as
twice daily unless conditions dictate more.  The detection technique has
evolved, the application has not, unlike the term applied to other unrelated
equipment.
 
I do not own or operate ionospheric sounding equipment at this time.  I have
many hundreds of "sondes" and their support equipment, in various forms and
application, dating back to 1929.
 
Ionosonde - Balloon borne (carried, not birthed) device used to measure
ionizing radiation in the upper atmosphere.
 
Ionospheric Sounder, sounder, shortened to sound, erroneously assumed to be
synonomous with "sonde" in application and incorrectly applied, thus
creating Ionosonde - Ground based transmit/receive system used to assist in
determination of reliable communications paths by frequency at a given time
on HF.
 
I have photos of Ionosondes for those interested, ionospheric sounding
equipment photos can be found on the web.
 
Anyone have an actual Ionosonde?  Need some extra $?  I'm interested if it
is for sale.
 
While we're at it, anyone know the upper limit of NVIS?
 
Kurt

[cmradio]

While we're at it, anyone know the upper limit of NVIS?

Now that's where the dudes of the HF Beacon Society provide a valuable service

Peace!

[Token]

Here s a shot of a couple sweeping from about 6600 to 28000 kHz.  It actually did go to 28000, although it is hard to tell on this image because of the traffic near there, I had to magnify the screen in real time to see where it ended.  Normally I can not see them this wide, typically I only see a given one for 12 MHz or less, what end of the spectrum depends on time of day.

[SW-J]

Here s a shot of a couple sweeping from about 6600 to 28000 kHz. 
...

Several different sweeps - or several 'returns' from the same Ionosonde transmitter?

It appears one of the sweeps converges with the long one about 17 MHz ... and there is a faint trace of a third starting lower down about 16 MHz and another about 20.5 ...

Usually the Ionosonde transmitters are staggered in time, that is, they have an assigned 'time slot' if you will around the hour so they do not overlap and cause a signal to appear at a receive site that was unplanned is and therefore unknown ...

[Token]

Several different sweeps - or several 'returns' from the same Ionosonde transmitter?

It appears one of the sweeps converges with the long one about 17 MHz ... and there is a faint trace of a third starting lower down about 16 MHz and another about 20.5 ...

Usually the Ionosonde transmitters are staggered in time, that is, they have an assigned 'time slot' if you will around the hour so they do not overlap and cause a signal to appear at a receive site that was unplanned is and therefore unknown ...

Several different ionosonde transmitters.  Not all of them sweep at the same rate, thus different slopes on the display, and it is not uncommon for them to cross at times.  Yes, I know they are often quoted as "100 kHz per second" sweep time, but some are intentionally faster or slower, I have seen sounders sweep anything from 50 kHz per second to 250 kHz per second.