Messages

781

HF Beacons / Re: Irregular dashes 6940 1025 UTC 16 Aug 2016

« on: November 26, 2016, 1637 UTC »

Looking back through my logs I find the first log entry for this dasher on Aug 11, 2016.  The first recording I find in my server is Aug 12, 2016.  But there is a very similar signal recorded April 28, 2016, that could be related.

T!

782

HF Beacons / Re: Yosemite Sam Dasher

« on: November 26, 2016, 1551 UTC »

Heard locally here @ 1532 UTC, 26 Nov, 2016.  Center freq 6498.65 kHz.  About 0.72 sec long dash sent every 3.1 sec.

Buried inside a Russian AT3104D modem right now, but can tell it is there.

T!

783

Other / Re: UNID 6940 CW 26 November 2016 @ 0410z

« on: November 26, 2016, 0505 UTC »

This has been seen before, and also posted here  https://www.hfunderground.com/board/index.php/topic,29519.0.html

T!

784

HF Beacons / Re: Irregular dashes 6940 1025 UTC 16 Aug 2016

« on: November 26, 2016, 0451 UTC »

This appears back at 0430 UTC on Nov 26 2016.

T!

785

General Radio Discussion / Re: Book - Signal Analysis for Radio Monitoring

« on: November 26, 2016, 0232 UTC »

https://planesandstuff.wordpress.com/2014/03/14/book-review-follow-up/

That review is not for the book in question, "Signal Analysis for Radio Monitoring".  Rather that review is for another book by the same author, called "Technical Handbook for Radio Monitoring HF".

T!

786

General Radio Discussion / Re: Book - Signal Analysis for Radio Monitoring

« on: November 26, 2016, 0230 UTC »

I have this book, as well as a couple other of Rolands works.

"Signal Analysis for Radio Monitoring" is a good resource.  It tells the basics of digital signals, defines how to determine modulation types and baud rates, and generally helps to categorize signals.

While it is very good at helping you figure out the modulation specifics, it is not good at, nor is it supposed to be, telling you what kind of signal it is or the source of the signal.

Let me give an example.  The book tells you all the information you need to figure out that a given signal might contain 12 QPSK, 120 Bd, channels and a 3300 Hz pilot tone, and it tells you what is meant by each of these features.  But it does not tell you that based on these features this is most likely a Russian AT3004D or AT3104D modem.

This might be because one of his other books, "Technical Handbook for Radio Monitoring HF", does tell you that if you have a signal with 12 QPSK, 120 Bd, channels and a 3300 Hz pilot tone it might be a Russian AT3004D or AT3104D modem.

"Signal Analysis" can sometimes be hard to follow, it is not necessarily laid out in a way that flows well from section to section.  However, I have to say, I do not know what could be done to improve it, so maybe just the subject does not lend itself well to logical flow.

The book references specific software in examining features of a signal, this software is Adobe Audition 1.5, Sound Card Oscilloscope, HOKA Code 300-32, and PROCEED.  Most people probably do not have that exact suite of software, and the book could be improved by using more common or generic software examples.  However once you figure out how to use what software you do have to do similar tasks the examples in the book can really lead you well.  And if you understand what is being done in each case (aptly described in the book), and not just try to match the images in the book, it is very useful.  The book does contain the information you need, in most cases, to use other software, but there is a bit of a curve in doing that.

T!

787

HF Beacons / Re: The 4070 beacon

« on: November 19, 2016, 1309 UTC »

Is this a night time only beacon?  This morning (19 Nov 2016) I was recording it and it turned off at 1243:37 UTC.  Signal was there, not strong but at least 7 or 8 dB above the noise floor, and then it was gone, no fade out.  I watched for about 10 minutes and no return.

I did notice another signal that could be a beacon, but might not be, on 4072 kHz.  It is a 3.75 second dash sent every 6.1 seconds.  There is a second part to this signal, at the end of each dash the signal pauses for 0.22 sec and then shifts freq to 4071.93 kHz, and sends a very short dit, about 0.14 sec long.  I can't think of a digital signal that matches these parameters with any pilot tones or that kind of thing, so if it is a resting digital signal I don't know what it is.

T!

788

Equipment / Re: Tecsun PL-680 Sensitivity Tests

« on: November 19, 2016, 0453 UTC »

Don't take this as a slam on your post and video, it certainly is not.  I thought the comparison was interesting and well done.  Also you specifically mentioned the ability of the FTdx-3000 to pull out signals in interference situations.  However sometimes new listeners, or people looking for guidance on receiver purchases, misunderstand such comparisons.

So a few comments for people new to the hobby.  This is not to be taken as disparaging of the Tecsun, several of their portables, including the 680, are exceptionally good for the price point.  If what you want is a portable with about as good performance as you can get for that price the 660, 680, and 880 are very good.

Raw sensitivity is seldom a problem these days, for any radio.  From the cheapest to the best, they will mostly have sensitivity within a few dB of each other.  What sets apart a good receiver from a so-so receiver are other features, such as dynamic range, close and far filter blocking, image rejection, etc.

That, unfortunately, can mislead new or inexperienced users.  They see tested or published sensitivities and filter widths (without understanding the need for more than one number to define filter performance) and assume that anything with the same filter width and sensitivity must perform about the same.

I had a new user tell me one time that he tried a specific portable against a top of the line contest rig, and that the portable could hear easily 90+% of the broadcast stations that the contest rig could.  And the portable was 1/100 the cost of the contest rig, so people would be stupid to buy the contest rig over the portable.  He did not understand that it is not the performance with the 90% of the strongest / clearest stations that defines a good radio, but rather the performance against the 10% of the weakest / most interfered with stations that shows how good a radio is.

As a general statement, if what you want is a receiver to pick up shortwave broadcast stations, several of the better portables out there will serve almost as well as a high end desktop radio.  It is only when you get into more exotic signals, or some of the really hard to catch broadcasters, that the desktops shine.

T!

789

Spy Numbers / Re: HM01 ?

« on: November 19, 2016, 0419 UTC »

Specifically here:  http://www.numbersoddities.nl/V02a-M08a-HM01-schedules.pdf

T!

790

Other / Re: Pips Network? 1909 UTC 16 Nov 2016

« on: November 17, 2016, 1319 UTC »

This set of signals was up from before 1815 UTC to 2033 UTC, 16 November, 2016.

I was not able to access HFU to post yesterday, so will add info today.

In this case the CW dash was 1.0 second long, and the dash happened about every 51.625'ish seconds.  When I first saw it on 11150 kHz I did not think it was the Pips network, as I have never seen that system use anything like that repetition interval, the previous longest interval was 10.5 seconds.  Intervals of 3.0 to 10.5 have been seen and recorded.

However, after finding a few more frequencies in use, confirming that those frequencies were indeed past used Pips freqs, and confirming that the frequencies are being sequenced just as all past Pips freqs are, I decided it was probably the Pips network, just with an interval much longer than we have seen before.

I made wideband recordings that I have yet to review, so the frequency list is probably larger than below.

(edit after recording review) Frequencies seen so far:

11150
11200
11550
12025
13200
13400
13875
14400
15100
15625
16000
16725
17475
17775
18025
18625
19300

That should be a complete list from 11150 to 19300 based on checking each pulse as it sequenced on the recording.  However the spacing allows for a lot more freqs, so I assume there are freqs below 11150 and possibly above 19300 that I could not receive.

T!

791

HF Mystery Signals / Re: Mystery signal question

« on: November 15, 2016, 1339 UTC »

I think the Aricebo HF transmitter is 0.6 MW, not 6 MW

6 MW is EIRP, I guess.

The Aricebo ERP is 220 MW at 8175 kHz and just under 100 MW at 5200 kHz.

They are almost certainly noise from some production technique, RF welding, etc.

The HF generators of such industrial plants must have frequency inside specially allocated ISM bands which are mostly the same in various countries: 6765 - 6795 kHz, 13553 - 13567 kHz and 26957 - 27283 kHz for SW. And even taking into account the fact of presence of non-standardized plants of such kind or some spurious emissions, the most activity of the "sweepers" must be observed on these ISM bands. However, it is not obviously on the posted screenshots: they are active on 24 and 28 MHz instead.

Yes, and those facts are why I did not say these signals ARE from things like RF welding, and rather said "almost certainly".

However, I have seen visually identical signals from a plastic welder, and it was slightly outside the ISM bands (in that case 25 - 26 MHZ).

Combine that with the fact I see the majority of these signals (outside the ISM bands) when propagation is in from Asia, and China is well known for ignoring the rules and doing their own thing, and I think the majority of these that I see are quite possibly, almost certainly (but not quite certain) are some similar industrial technique.

Of course, that is why this is still a mystery.  A list of possible sources has been ruled out, the most probable source should not be happening on these frequencies, and at this point we are still guessing.

With the signals I was looking at locally there was a definite reduction in number visible on any given Sunday.  I plotted this over a period of 6 weeks and every Sunday the number was less than one tenth of what was seen on Saturday and Monday.  This is a strong indicator, in my opinion, that these signals are man made.

The waveforms are unstable and varied, especially in phase.  And there are seemingly many different sources up at any time (based on propagation and antenna bearings).  These would argue, to me, against things like research facilities, which should be few in number and probably using more traditional or predictable waveforms.  Also, research tends not to avoid one specific day of the week, you generally do research when you can get the time on the facility or when the conditions are right for your tests.

Just my opinion of course.

T!

792

HF Mystery Signals / Re: Mystery signal question

« on: November 14, 2016, 0156 UTC »

How about radar astronomy, an active radio-astronomical technique of observing nearby objects in the solar system (asteroids, comets, etc.)? There are microwaves are mostly radiated, but Arecibo Observatory in Puerto Rico, for example, has also one 6 MW radar transmitter system for 8 MHz band, so SW is also being used for this purpose? Could China or Japan, for example, have the similar systems operating on SW? Are short wave frequencies being used on Goldstone Solar System Radar too?

I think the Aricebo HF transmitter is 0.6 MW, not 6 MW.  Regardless, no these are not radio astronomy.  They are almost certainly noise from some production technique, RF welding, etc.

And no, Goldstone does not do HF.

T!

793

North American Shortwave Pirate / Re: Wolverine Radio 6950 kHz USB 0120 UTC November 13, 2016

« on: November 13, 2016, 1950 UTC »

I thought that image by Wolverine looked familiar.  He used the same image back in 2012.  Here is the shot from March 25 of 2012:



T!

794

North American Shortwave Pirate / Re: UNID SSTV 4020 USB 0413 UTC 11/13/16

« on: November 13, 2016, 0422 UTC »

Here is my copy of it:



T!

795

North American Shortwave Pirate / Re: Wolverine Radio 4020 USB *0218 UTC 11/13/16

« on: November 13, 2016, 0328 UTC »

Signal on 4020 kHz was only slightly less good than on 6950 kHz for me.  Audio was fine, SSTV showed a little more noise.

Thanks again Wolverine.

And of course, right into a second show on 4020, excellent!  Playing on the house sound system now

SSTV from first show on 4020 kHz:



(edit) later image for second show here, image should be better than this, but Olivia started up on 4019 at about the same time, so messed it up:



And someone responded with another SSTV, no idea who, here it is:


T!