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Topics - GC

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1
Propagation / Long delayed echo
« on: July 28, 2018, 1443 UTC »
Early Saturday morning is one of those times I find that I have a bit of quite time that I can spend "spinning the knobs" of my radio.

Around 11:00 UTC (7:00 EDT) I was scanning through 11MHz and came upon a signal that at first I thought was HFGCS on 11175kHz but was not on that frequency.

I thought of HFGCS (i.e. MAINSAIL) due to the "echo" noted on the audio.

However the frequency was 11279kHz and was Gander Radio with an echo of about one quarter of a second (wild guess). At first only Gander Radio was effected and the aircraft transmissions were not. After a short while the echo on Gander Radio's transmissions diminished only to return again for a while and I could hear this same echo on at least one of the transmissions from one of the aircraft but missed which one. This effect did not last that long was effectively gone by about 11:30 UTC.

I attempted to listen to Gander on a couple of the online Kiwi SDR's but was not quick enough - I didn't hear Gander at all on some or only weakly on others.

I managed to make a short recording - about 1:15 in length (14mb in size), I have posted it here:

https://www.dropbox.com/sh/ix7wo4xgai7xvze/AAAmvMfvBes-Ylk1N2p5gWk1a?dl=0

for anyone who might like to have a listen.

The first part of the recording shows a very clear and distinct echo. About a half minute later it is almost completely gone. Unfortunately I did not get a recording of the aircraft's transmission having the same sort of echo.

I have heard echo's and delays before but this one is the clearest and most distinct that I can recall.

Some consider long delayed echoes to be those of greater than a couple of seconds while others have a much looser definition. A quick search using Google or your preferred search engine will find much food for thought.


cheers, G near Ottawa Canada





2
HF Mystery Signals / UNID 12185 kHz 25kHz wideband transmission
« on: July 14, 2018, 1614 UTC »
I have been stumbling across some wideband transmissions for a while which are quite strong in Eastern Ontario


Just a while ago, 12185kHz was active, went off the air 2018-07-14 15:45 UTC


About 25kHz from edge to edge
Reminds of some of the OTHR like 29B6 Kontayner OTH Radar: https://www.sigidwiki.com/wiki/29B6_%27Kontayner%27_OTH_Radar  but doesn' quite look the same on the waterfall but then again I am not that familiar with identifying this particular signal.


I attempted to use the KiwiSDR TDoA capability and my feeble attempt seems to indicate a location somewhere in middle USA, coincidentally near lower Lake Michigan and the suspected location of the UNID 1 PPS pip/tick/time signal.


screen grabs here:


https://www.dropbox.com/sh/5ft6rovgskodzdg/AACG7uNgNNLgWda4fkGU_2wMa?dl=0


I have not yet mastered the fine art of linked images to postings on hfunderground so for now I will only provide a link to a folder on dropbox, file names should be intuitive enough.


cheers, Graham near Ottawa Canada





3
HF Mystery Signals / UNID wideband signal 13995.6 kHz
« on: July 13, 2018, 2213 UTC »
UNID wideband signal 13995.6 kHz just below the amateur 20m band


very strong with some fading in Eastern Ontario  SINPO 41144.


tuen 13995.6 kHz in USB  signal is about 5 kHz wide. Sounds a bit like HFDL or one of the TOR (i.e. sitor) modes but I am not quite sure what it is.


I used the KiwiSDR TDoA and my feeble attempt puts it around Dallas Texas. I will post some images, recording, etc later on.


cheers, Graham near Ottawa Canada


4


As some may have already heard, the KiwiSDR network has had a new feature added to it's already impressive capabilities and that new capability is the ability to do Time Difference of Arrival ( TDoA ) in near real time on LF/MF/HF signals.

first post (that I noted) on the development was here:

https://www.rtl-sdr.com/locating-various-hf-transmitters-and-number-stations-with-kiwisdrs/

The authors very interesting web page here with lots of details on this and other interesting topics:

http://hcab14.blogspot.com/

a follow up on the first link here:

https://www.rtl-sdr.com/kiwisdr-tdoa-direction-finding-now-freely-available-for-public-use/

and a posting on qrz.com on someone's first use of this KiwiSDR capability and using to located the UNID 1 PPS PIP/tick/time pulse:

https://forums.qrz.com/index.php?threads/time-signal-intruder.614510/page-31#post-4727876

I tried this technique last evening and my results were similar to those described by the poster on qrz.com

cheers, Graham near Ottawa Canada


5
Stumbled across a link to this on Hackaday of some interesting HF activity that may (or may not) be related our mystery one PPS time tick signal

https://sniperinmahwah.wordpress.com/2018/05/07/shortwave-trading-part-i-the-west-chicago-tower-mystery/

Not suprisingly, I noted a comment by Chris S in the comments section of above noted posting.

cheers, Graham near Ottawa Canada

6
hearing the ditter on 6720, 6820, and 6920 kHz  100kHz offset from each other but I haven't looked either higher or lower yet.

Signal strength is strong in Eastern Ontario.

So far I have not heard any "double" pulses and I am starting to look above and below these three frequencies

cheers, Graham  near Ottawa Canada

7
HF Mystery Signals / PIPs 2018-04-19 22:45 UTC
« on: April 19, 2018, 2326 UTC »
PIPs active on numerous frequencies

PIPs were already active when I first them at 2018-04-22:45UTC

Pulse width of the several frequencies I measured is 64ms. PIP repetition rate is once every three seconds.

when viewed on the waterfall of a SDR, adjacent PIPs seem to in or at least very close to being in sync

signal strength is quite strong  S9

Frequencies:  (all frequencies in kHz and is CARRIER frequency, tune -1kHz for USB)
5970
6240
6330
6420
6720
6820
6920
7020
7460
7570
7680
7800
7920
8040
8160
8280
8400
8530
8660
9050
9190

still active at 2018-04-19 23:25UTC

cheers, Graham near Ottawa Canada

8
HF Mystery Signals / All 1 PPS pip / pulse / tick logs here please
« on: March 13, 2018, 1549 UTC »
good day all,

There has been an UNID 1 PPS time tick ( or pip if you prefer ) transmitting between 10100 and 10150 kHz from time to time.

A search online of reports of similar signals has found a few references including some from around the first of January this year of a similar signal on the lower end of 7 MHz.  I have noted this signal mostly between 10100 and 10150 kHz but also have noted it on 7 MHz as well.

Activity is intermittent, some times on the weekends, sometimes on weekdays but always during the day Eastern time on 10 MHz and when noted on 7 MHz in the evening.

The signal appears to be synced with UTC (i.e. in step with WWV) but does not ID as does WWV nor does it change from a steady 1 PPS tick although I have on occasion thought that I have heard an occasional double tick.

Each 1 PPS tick is 16ms in length with a very sharp rise and fall time giving it very harsh sound. This also gives it a rather wide bandwidth.

The signal changes frequency from time to time but appears only frequencies divisible by 5 kHz, i.e. 10100, 10105, 10110, 10115 ... (etc).   These are carrier frequencies and you would tune 1 kHz lower for USB or higher for LSB. I have not noted any obvious pattern to the frequency changes. It sometimes appears as though the signal will change frequencies if there happens to be an interfering signal nearby - almost like it changes to find a frequency with no interference or less likely changing to one where it will cause less interference.

Assuming that the 1 PPS tick is synced to UTC and using simple time of arrival measurements, the origin is definitely in North America and an arc ( just over 1550 km) drawn from my location in Eastern Ontario includes northern Florida, central US and on up into Manitoba.

When I have monitored this signal it's strength is quite strong, S9+ and typically stronger than anything else I can hear nearby on 10xxx

I did not note this signal on this past weekend (March 10/11) nor yesterday ( Mar 12 ) but it was on this morning starting around 2018-03-13 12:30UTC and was active for about an hour and used 10100, 10110, 10120, 10125, 10130, and 10150 kHz.

I have attached a screenshot from this morning when it was on 10130 kHz. You can see how strong a signal it was with reference to other nearby signals. Those around 10138 kHz are amateur digital signals likely JT65 or similar. Signal strength alone seems to indicate power levels greater than typical amateur radio use on 30m.

I have been poking around the FCC and Industry Canada databases for licencees that might match but so far I haven't managed to look under the right rock.

There is a US company, URSANAV which has been promoting eLoran as a supplement to GPS for timing purposes due to the recent interest in mitigating some of the spoofing issues being seen with using GPS only. I wonder if there is some commercial company testing out something else but on HF.

Interesting mystery

cheers, Graham near Ottawa Canada


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