Utility World

SDR Captures

SDR captures are made on a WiNRADiO Excalibur Pro at the usual location in Southern California. A look around the World Wide Web will turn up other waterfalls, audio decodes, and even some DDC recordings. This is one of the best uses for SDRs in utility DXing.

RF Waterfalls:

Cuban SK01 (Rotated 90 CCW)
SK01 is called that because the first transmissions were in PSK31. They have since shifted to a direct binary transfer mode called RDFT (Redundant Digital File Transfer). Here, we see the classic RDFT waveform with its repeated bursts using 8 data tones. However, since nothing's ever normal in Cuban numbers, they usually send it in AM instead of the USB mode intended by the mode's designer. The bright line in the middle is the carrier on 9153 kHz, and we see the RDFT in both sidebands.

We know now that this AM transmission of SK01 was a precursor to Cuba's new hybrid mode transmission where the traditional machine voice announces the message number as in V02, and then the RDFT is sent as in SK01. This AM mode is known as HM01, and it is replacing many V02a and M08a schedules. HM01 captures will be uploaded as time allows.

CHU Time Signals (Rotated 90 CCW)
CHU is the standard time and frequency station operated by the Institute for National Measurement Standards at the National Research Council of Canada. It's on 3330, 7850, and 14670 kHz. The bright line in the middle is a full carrier, the frequency of which can be considered standard. It's easy to see that there is no lower sideband (H3E emission). We were lucky to get the top of the hour here, as shown by the long 1-kHz pulse after the voice announcement, and then the 9-second silent interval.

Strange US Air Force Broadcast
This Emergency Action Message was broadcast on September 20, 2012 by Andrews in Maryland. Note the repeated audio bands taking up at least five times the bandwidth of a normal upper sideband voice signal. Five of these bands are visible, with the brightest one (second from the left) being the fundamental on 11244 kHz. The leftmost one is where the lower sideband would be, but it is in fact an un-inverted copy of the fundamental. The fifth band, farthest to the right, is partially covered by locally generated electronic noise. All of these bands had the entire voice signal when tuned in. A heavy white-noise type of wideband hiss was also present.

UK Akrotiri Radar - Abnormal Shutdown
The wide signal of the UK radar from the Pluto-II antenna in Cyprus usually just stops. This time, though, it kept sweeping a single tone back and forth for about one minute, interfering with broadcast signals around 9450 kHz.

Digital Radio Mondiale
DRM is a proprietary (DRM Consortium) technique for broadcasting FM-quality audio over ordinary 10-kHz channels in the static-y old HF band. The sound can be awesome. The three bright lines are in every DRM signal, and the leopard-skin effect is caused by selective fading. Modulation is quadrature PSK on a large and varying number of COFDM carriers. Narrower variations of DRM are being used for file transfers by amateurs, and possibly utilities.

HF Radars/ Ionospheric Sounders
HF radar stations and certain types of ionospheric sounding use fairly similar waveforms, and in fact these are often used together, since soundings help the radar operate well. This means that the higher end of the usable HF propagation range can often become the kind of zoo we've caught here. These are likely sounders. We have several different CWFM (continuous wave frequency modulation) waveforms (highlighted in red), all jumping around the waterfall like fleas on a piece of paper. Go here to stream a long (1:30) clip I've edited together of "The Foghorn," "The Phaser," "The Frog," and other representative noises.

The Frog
This is a particular member of the sounder/radar zoo, in which series of bursts come together, like the regular croaking of a frog. Four seems a common number, but some on our sound clip mentioned above have more. All bursts are about 8 kHz wide, and each one has a different sweep rate. It sounds less to me like a frog than a different, more rude, noise.

Chirpsounders (Reduced) (hear it)
"Chirpsounder" is a proprietary name for apparatus made by BR division of TCI, but it's also generally used for any ionospheric sounder which sweeps a single carrier upwards across the entire HF band at a speed generally around 50 kHz/second. It's no surprise that these show up on the full-band waterfall as an oblique line moving down and to the right. The surprise here is that, despite every book and Internet source describing it as a single carrier, we always see the two frequency-displaced lines of slightly differing slope meeting around 18 MHz.(Here, these lines have been augmented with Photoshop to allow visibility at the resolution used.) One of these lines seems to be discontinuous.

Similar screen dumps posted by "Token" and others using the same equipment look the same. The time displacement at either end is on the order of seconds, far too long for ionospheric delays, not to mention too consistent. One really wild guess is that the other line might be the "Chirpcom" I've read about, which allows short text broadcasts to the sounder's receivers. If you wondered why the upward (in USB) dweeeeep of the Chirpsounder always seems to occur twice, wonder no more. That's exactly what it sounds like in the typical voice bandwidth receiver.

There's another upward sweeper called a Digisounder, which moves up HF in uniform steps, sending a little short sweep at each one. Its plot looks about the same, only it shows up in extreme zooms as little squares. So far I've never found one with good enough resolution to post here.

Squiggle #1 (hear it)
"The Squiggle" is a long standing mystery. The name, which I didn't make up, is descriptive of both the sound and the appearance on spectrum displays.

A typical Squiggle sweeps downward over a very wide range, while all the time also slowly FM-ing back and forth. Usually the sweep rate slows down at the end, causing the distinctive squiggly noise if you're tuned near the bottom.

This first example is actually a double Squiggle that appears from time to time. Here, the normal downward sweep is seen at the right, and a somewhat more compact one appears at the left (lower in frequency). This and the more typical single Squiggle have both been reported worldwide, anywhere between 10 and 40 MHz. Here's a single Squiggle received here above 30 MHz.

It is not local QRM, as this dump from the WebSDR in the Netherlands will prove. It is not from the usual suspects such as HAARP (which never transmits that high) or ordinary sea radar. That said, I still think it's human caused. This view is supported by the noise's tendency to recur at very regular intervals. It also possesses some signal characteristics that are, on occasion, also found in known spurious emissions.

Squiggle #2
In this more elusive Squiggle, the signal parameters are reversed. The FM on the carrier is wide, while the slower sweep is narrow. This differs from radars/ sounders shown above in that the overall frequency range changes during the burst. Here, a whole gaggle of these have come out at once, overlapping each other. It's possible that these are some kind of malfunction of whichever system makes a straight version of these. A good candidate for this would be the "New Woodpecker," a radar which sounds like a kinder, gentler version of the old one.

Stock Market Oddity
A look at the Spectrum Lab audio plot shows why I named this the Stock Market, since it always makes pictures that resemble the investment charts everyone looks at. One version sweeps three closely spaced carriers up and down at a predictable rate but by a completely unpredictable amount. Another one is just noise, and it has a less predictable rate. Neither one ever fades, and they seem to be locally generated, no doubt by badly filtered consumer electronics.

Stock Market Oddity (with Squiggles) (hear it)
The Stock Market really, really does seem to be locally generated. Why, then, did this one around 20 MHz eject a series of Squiggles going down 160 kHz, as we see at 19 seconds on this SDR waterfall?????????? Just lucky?

Entire 20-Meter Amateur Band (Hi-res/large)
This remarkable capture shows ALL of the amateur 20-meter band at one of its busiest times every year, namely the beginning of the ARRL Field Day contest. Note CW packed in at the low end, then digital modes, RTTY, packet/Pactor, a dead spot, and finally the upper-sideband voice. Check out the digital SSTV (in a variant of HamDRM) with its "END" waterfall picture. Finally, at the top band edge is a wideband multi-tone signal of unknown origin, which is obviously an intruder. Write 'em up, boys.

Entire 40-Meter Amateur Band (Hi-res/large)
Like 20, only later at night when the Field Day action moves downward. The voice signals at the top are in lower sideband. The wide AM broadcast at the high end is actually outside the band. Most of these broadcasters were moved out by new ITU regs a few years back, giving us the top half of 40 back.

Entire AM Broadcast Band (Hi-res/large)
This one's reduced from an absolutely enormous file, but it's still pretty good. We see the whole Los Angeles AM radio band, including the weak travelers' information stations above and below. The fuzzy light bands at either side of some signals are digital HD radio using IBOC (In Band, On Channel) modulation. With IBOC, the densely packed stations are now crammed in even tighter.

I/Q Displays:

Sea Surface Radar
One way to view signals with very wide bandwidths is to send the SDR output as stereo I/Q (in-phase/quadrature) to analyzers like Spectrum Lab. This gives a much better visualization of wide signals such as the sea surface radars common at night between 4 and 5 MHz. These are typically 25-30 kHz wide, with a one or two Hz sweep rate. This particular specimen is centered on 4550 kHz. The ticks down the left side are for seconds, so we see that indeed the radar does make exactly one sweep per second. What's somewhat anomalous here is the appearance of a second sweep, perfectly synchronized in frequency and offset a little less than half a second. It is not known if this is part of the same radar system or if it is another one on the same frequency.

Akrotiri "Pluto-II" Radar
(Hear it in this video *plugin may be required*)
This awesome signal comes from the over-the-horizon HF radar at the UK base in Akrotiri, Cyprus. Pluto-II is said to be the name of the giant antenna constructed on the salt flat near the coast. The signal is continuous, unlike other such radars, and it is about 19 kHz wide. The center frequency (0) is about 10505 kHz. This system typically sets up on multiple frequencies, which change after several minutes. The leopard skin pattern is caused by selective fading. Tuning anywhere in the signal with a standard USB receiver produces a sound very much resembling the Goodyear blimp. Hear it in this video (Plugin may be required).

The Wide Phaser (Reduced 50%)
"The Phaser" was named early on for its resemblance to the various space gun noises in Paramount's old analog library. It's likely a special case of the CWFM sounder zoo with a lower sweep rate, sometimes down to ~2.5 Hz. This version, however, is much wider, ~30 kHz, than the rest. Its purpose is unknown. The plot, while kind of murky, still shows about 4 sweeps/second, just about right for blowing up Romulan Birds of Prey. Notice the appearance of audio beeps before the bottom (first) burst, but not the top (second) one (hear it). This inconsistency is one of several odd things about this very odd signal.

The Foghorn
Basically a slowed-down Frog. It's a bit wider (10 kHz), and it parks on a single frequency, sometimes for hours. Its bursts are the usual CWFM stuff, but at a regular interval and always with the same sweep rate. Its frequency selection isn't always the best, though in this case everything else you see is noise from various electronic devices in the shack.

Squiggle #2 (With two #1s) (hear it)
As we've seen, Squiggles like to come out and play together. Here's the wideband IF dump for a major Squiggle #2 attack just above the US Citizen's Band during a red-hot skip opening to South America. It's punctuated by a couple of appearances of Squiggle #1. Our monophonic audio mixdown gives a good sense of how regular Squiggle #2's sweeps are.

(2001-2012)

In previous years, national security crises have sometimes led overzealous US Government officials to target harmless ham radio or utility hobbyists. Therefore, it is imperative that people in these hobbies make it clear which side they are on. We've helped secure this country in the past, and we'd like to again if the need comes up.

Even in the "pre-9/11" USA, laws and temporary measures were ocasionally passed that severely restricted freedom to listen, and on one occasion even confiscated equipment. Furthermore, the original US Communications Act and certain sections of the later ECPA also remain in place, and lax enforcement should not be taken for their irrelevance. Basically, the law of the land protects the secrecy of all radio traffic not explicitly intended for the public. Most other countries are stricter than the US, and we'd really like to keep it that way. Common sense remains a very useful guide. When in doubt, leave it out.

Keep in mind that short wave radio is an extremely ambiguous medium, which gives few reliable clues as to the exact nature of strange signals. While some of these are undoubtedly just what one suspects they are, there's plenty of room for misunderstanding. Beware of fake communications, exercises, misinterpretation of code words or accents, and hoaxes perpetrated to whip up panic or xenophobia. These have happened before, they are happening right now, and they are sure to happen again. But if a VERY carefully considered and documented analysis tells you that you've run across something real, seriously consider contacting relevant authorities, carefully explaining yourself and what you do, and noting that you have encountered suspicious communication without giving details until they are requested. More than one spy has been shut down this way, even in the era of satellites and Internet.

Far as security holes go, there will never intentionally be one here. Information comes from unclassified sources, even if these become classified at a future time. Furthermore, it is a fundamental policy of Utility World not to report frequencies, call signs, or activities from such sensitive areas as the Persian Gulf and Afghanistan. This hobby is plenty of fun without endangering our military.

What's a Shortwave Utility?

A utility is the jargon for any radio station on the short wave band that is not for the public's entertainment or hobby. All those huge gaps on your shortwave radio, the ones between broadcast and amateur bands, are utility bands allocated by international treaties.

The word "utility" comes more or less from the original Latin for "usefulness." With very few exceptions, these radio communications are most certainly being used as part of some mission or task, known or unknown.

Utilities are harder to hear than broadcasts, but they're way more fun. You'll find all the world's militaries, ships, aircraft, spies, bootleggers, embassies, and anyone else who needs to communicate over the horizon. While satellites are often primary, the recent failure of Galaxy IV shows once again why many people want a shortwave backup. If your radio has a "USB" or "CW" setting, you're ready to give utilities a try.

The Utility World column and its web site are intended as friendly, jargon-free clearinghouses for utility information, so you'll hear more signals and fewer odd noises. In other words, you folks write both of them.

CU on the bands!

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