Author Archives: Chris Smolinski

Lies, Damned Lies, and Receiver Images

Posted on by
2

I have my SDR-14 receiver online, for some listeners to use. The other day, there was a logging of Trenton military aviation weather on 6950 kHz. I had not seen other reports of Trenton aviation weather on this frequency. And, since 6950 is a very popular frequency for pirate radio in the USA, this could cause some concern, as QRMing military stations is generally bad karma for pirates.

Here is a recording of Trenton Aviation as received on the SDR-14.

As it turns out, I had been running a recording of 6800-7000 kHz via another SDR, my netSDR. So I went back, and checked that recording at the same time the SDR-14 had picked up Trenton on 6950. Nothing. Nothing at all. And the netSDR is connected to a much better antenna than the SDR-14. Hmm. This is strange.

Last night, I was alerted that Trenton was again being heard on the SDR-14 on 6950 kHz. So I went and tuned in on the netSDR, and again heard nothing. I then decided to look for a schedule of frequencies used by Trenton, and found that they should be on 6754 kHz. I tuned in, and sure enough, there they were. Coming in very well, about S9+30 dB or so. Hmm… I did a quick calculation, and the difference between 6950 kHz and 6754 kHz is 196 kHz. 196 kHz, that sounds familiar. Why yes, that’s the I/Q sample rate of the SDR-14!

Now it all makes sense – the received signal on 6950 kHz is an image, a false signal generated by the receiver. It turns out that even SDRs are not immune to images. (Shhh… don’t anyone tell Al Fansome)

Images have been the bane of DXers for decades. They often manifest themselves as a particularly strong signal that is picked up on other frequencies. With an analog receiver, these frequencies are often offset from the actual frequency by the IF frequency of the receiver. With VHF/UHF radios and scanners, this is often 10.7 MHz, or close to that. In the case of the SDR-14, the image was located at an offset equal to the I/Q data rate. It was probably being heard on 6558 kHz (6754 kHz – 196 kHz) as well.

If you’re hearing an unexpected signal, one suggestion is to try another radio, ideally one with a different IF frequency. If you don’t hear the signal on the second radio, then it is most likely an image. Or your other radio is broken. But it’s probably an image. Ask another DXer if they can hear it, as well.

There’s a ham in Erie, PA that has been harassing the local club that runs a 2 meter repeater with claims of interference to the VHF marine band. The FCC has investigated, and found no interference. Multiple hams have contacted the Coast Guard and they have not had any interference issues. The only person who reports interference is the previously mentioned ham, who lives a few hundred yards from the building housing the repeater. I’ll close by noting that the VHF marine band is about 10.7 MHz above the 2 meter band frequency used by the repeater – 146.610 MHz.

Wolverine Radio SSTV

Posted on by
1
   PSK31     
   iPad app to decode PSK31     

Shortwave pirate radio station Wolverine Radio was on the air last night, with their typical excellent signal, excellent audio, and excellent programming. As is often the case, they finished their show with a Slow Scan TV (SSTV) image. SSTV is a way of sending an image using audio tones.

Here’s a video of the image, while it was being received. As you can see, it takes about 2 minutes to send a single image. Hence the name Slow Scan TV.

Here’s a larger video image, if you don’t mind rotating your head to watch it:

The image was decoded using the SSTV App for the iPhone, iPad, and iPod Touch which I will now shamelessly mention is

Here’s what the transmitted image looked like, by the way:

New version of SdrDx available, now for Windows also

Posted on by
Reply

There’s a new version of SdrDx, the free app for RF Space SDRs (SDR-IQ, SDR-14, netSDR, etc): http://fyngyrz.com/?p=915

This version includes a lot of new features, including recording I/Q data directly to disk, so you can then play it back. Think of it as a VCR. You can, for example, record the entire 43 meter band (6800-7000 kHz or so, depending on your SDR model) and then go back later and run the I/Q recording back through SdrDx again. It’s awesome! Previously I’ve had to run SpectraVue under vmware to do this, now I can do it natively on the Mac.

I use a program I’ve written myself, that reads in the I/Q data file, and plots a waterfall for the entire file. I can then selectively demodulate what signals I want. I can record all of 43 meters overnight, then check in the morning to see who was on, and listen in. I don’t miss anything, nor do I have to choose if there’s two, or even three pirates on at the same time. I can listen to all of them. At some point I may release this for others to use (Mac OS X only) but it’s still pretty crude right now.

There’s lots of other new features and improvements to SdrDx, so if you have an RF Space SDR, go download a copy to try out.

GPS Disciplined 10 MHz Reference

Posted on by
1
   HF Weather Fax     
   For Android     

Some time ago, I wrote about the Rubidium reference that I connected to SDR. The reference supplies a very stable and precise 10 MHz reference clock to the SDR, so that the sample rate does not drift. Drift in the sample rate causes drift in the received frequency, much like drift in the various oscillators in a conventional radio causes drift.

Just today, I replaced the Rubidium reference with a GPS disciplined reference.

Here’s what I got:

The reference itself is the box in the center. To the right is the power supply, to the left is the antenna.

A GPS disciplined reference or oscillator uses timing signals from the GPS satellites to control,or “discipline” the oscillator built into the reference using a tracking loop. The 10 MHz output is continuously adjusted to keep it at the correct frequency, usually by making very small adjustments and using long time constants (averaging periods), typically around 100 seconds or more.

The 10 MHz output from the reference connects to an input on the netSDR. Internally, that 10 MHz signal is used to produce an 80 MHz clock that is used to drive the A/D sampling.

Here is what the inside of the reference looks like:

Here’s a plot of WWV on 10 MHz:

I believe the frequency shifts you see are due to doppler effects in the ionosphere.

Now I can figure out exactly what frequency Captain Morgan is on.

Excellent 43 mb Propagation, 10/11 mb Operators Put On Suicide Watch

Posted on by
Reply

Old Sol has been quiet lately. Far too quiet for the 10 and 11 meter band guys. As I’m typing this, the solar flux is back into double digits, at 95. The Sun Spot Number (SSN) is officially 24, but you need to squint real hard to actually see any sunspots:

Sunspot SunSpeck group 1452 has pretty much rotated out of view, taking the meager solar activity we’ve had with it.

The NOAA/NASA/Space Weather prediction boys promise that we’re still a year away from the peak of cycle 24, and activity will increase.

Go up. Yes, it will go up any time now, just you wait. Hey! Look over there! Global Warming!

Meanwhile, back in the real universe, the background x-ray flux is at B1 levels.

So what does all this mean for us DXers? The lower solar activity has several major effects. First, the highest frequencies that can be propagated are lower, in many cases much lower. During a solar cycle maximum with high activity, the higher bands are often open 24 hours a day. With the lower activity we’ve been having, this is not this case. Yes, 10 meters is still open at times, but not nearly as much, or with the good conditions that have been experienced in the past. So operators and listeners need to move down to lower frequencies.

The foF2 frequencies are correspondingly lower, which means that a given band (including 43 meters) will go long earlier in the evening. Operators may want to adjust their schedules accordingly, and consider transmitting a little earlier to reach a semi-local audience. OTOH, they’ll end up reaching more distant listeners earlier in the evening as well.

Second, D-layer absorption is lower, due to decreased x-ray flux from the Sun. This means that lower frequencies are not attenuated as much, which is a good thing, since in many cases that’s all that is propagating. The last few days, I’ve been hearing 48 mb (6 MHz) Europirates fade in as early as 2 hours before local sunset. And once the Sun does set, their signal levels increase to really strong levels. Likewise, US pirates such as Wolverine Radio have been reported across the US and into Europe with incredible signal levels.

Third, the lack of major solar flares and coronal streams affecting the Earth means that geomagnetic conditions have been very stable. No geomagnetic storms means stronger signals, and less fading.

The net result is that reception conditions for 43 meter band pirates has been extremely good lately. Lots of operators and listeners have been taking advantage of the excellent conditions, loggings are way up.

There is a coronal stream expected to start impacting the Earth around the 13th or 14th of April, so we’ll have to see what effect, if any, that has on conditions. Until then, enjoy the great propagation!

SdrDx – Software Defined Radio (SDR) App for Mac OS X

Posted on by
8

Software Defined Radios (SDR) have revolutionized the HF radio monitoring hobby. While most of the SDR manufacturers only offer Windows versions of their SDR application software, there are many third party solutions for other operating systems.

I use Macs, and there’s a great SDR app called SdrDx. It is based on the open source CuteSDR program (which fortunately uses the more permissive BSD license rather than the overly restrictive GPL license, allowing a much wider use of the code). SdrDx is free to download and use.

SdrDx works with all SDRs made by RF Space. I believe it may also work with some soundcard based SDRs, although I have never tried it that way.

As obvious by the screenshot (from a 24″ iMac) there’s a lot of controls. Besides the typical waterfall and spectrum displays, there’s also controls for memories and notch filters, as well as the ability to control the various AGC and noise blanker settings.

There’s a readme file that comes with the download, and recent versions of SdrDx have an optional tooltip display, so you can hover the cursor over a control to find out what it does.

The author of SdrDx is actively developing it, and has added quite a few features based on user suggestions. If you run Mac OS X, and are looking for an app to control your SDR, SdrDx may be the way to go. Download a copy and try it for yourself.

Ops may wish to avoid 6950 kHz

Posted on by
1

I’ve noticed LINK-11 (TADIL – Tactical Digital Information Link) transmissions in the 6940-6950 kHz region the last day or two. Operators may wish to avoid 6950 kHz, and perhaps even 6955 kHz, especially while these transmissions are occurring.

I have no idea where these transmitters are located, but if I had to guess based on propagation characteristics, I’d say maybe Canada or out in the Atlantic.

LINK-11 is operated by the US military. I’m pretty sure you don’t want to interfere with it.

Global Pirate HF Weekend Results So Far

Posted on by
1

While conditions may not have been spectacular, I was able to hear a lot of stations. All heard with a JRC NRD 545 receiver and my 635 ft sky loop antenna.

Here’s what I’ve heard so far, all loggings reported to the HFUnderground.com message board.

Stations Heard UTC March 30:
Trans Europe 15020 AM 1420 UTC
Mike Radio 21455 AM 1356 UTC
Fox Radio 6308 USB 0010 UTC

Stations Heard UTC March 31:
Mustang Radio 15000 AM 1115 UTC
Trans Europe Radio 15020 AM 1125 UTC
Rave on Radio 6925 USB 1215 UTC
Radio Underground 15050 USB 1242 UTC
Radio Spaceshuttle 15845 USB 1223 UTC
Radio Underground 15850 USB 1302 UTC
Radio Paranoid 15030 AM 1134 UTC
Baltic Sea Radio 18950 LSB 1346 UTC
Radio Scotland 15060 AM 1400 UTC
Radio Mustang 15020 AM 1415 UTC
Cupid Radio 21460 1435 UTC
Cupid Radio 15070 1523 UTC
Radio True North 21850 AM 1529 UTC
Undercover Radio 15050 AM 1538 UTC
Radio True North 15520 AM 1623 UTC

Global Pirate HF Weekend March 31 – April 1

Posted on by
Reply

This is a great opportunity to hear a lot of Europirates!

Global Pirate HF-Weekend will be 31.3. – 1.4.2012. ( from http://hkdx2.blogspot.ca/ )

Be sure to visit either the #pirateradio IRC chat or Iann’s Chat while the event is taking place, to get current information on what stations are active.

1) RADIO SCOTLAND, Holland- 15.060 MHz – AM – 200 W
Saturdaymorning 08:00 – 10:00 h utc.
Saturday afternoon 14:00 (or 14:15) – 15:00 h utc.
Sundaymorning 09:00 – 11:00 h utc.
LIVE WEB-CAM: http://www.radioscotland.nl/Webcamrsi.html

Frequency 15.050 – 15.065 MHz, if 15.060 is occupied.

2) TRANS EUROPE RADIO, Holland – 15.000 – 15.100 MHz – AM – 65 W
Will be active during Saturday and Sunday morning and afternoon
on 19 mb.

3) BALTIC SEA RADIO, Scandinavia – 21.485 MHz – USB – 80/150 W W
On Saturday starting 08.00 and again 13.00 utc
On Sunday starting at 09.00 utc.

4) RADIO BORDERHUNTER, Holland – around /15 MHz/ 21.5 MHz – AM
More information later for dates and frq’s

x) OLD TIME RADIO, Scandinavia – 15.009 MHz – AM – 50 W
Short test was planned but cancelled for this weekend.

5) RADIO BLACK BIRD, Holland – 19 mb – AM
No frequency or time information yet.

6) WR INTERNATIONAL, England – 12.257 MHz – AM – 35 W
WR is on the air every Sunday from 08.00 – 11.00 utc.

7) BALKAN RADIO INTERNATIONAL – ??? MHz – AM –
New station from Balkan area. The station has new transmitter and
let’s hope it will be on air for this weekend.

8 ) RADIO SPACESHUTTLE, Scandinavia – 15.845 MHz – AM+SSB – 200 W
Saturday and Sunday some transmissions between 07:00-16:00utc on
15845 kHz (or nearby). AM and SSB (changing time to time)

9) FREE RADIO NOVA, Holland 15.070 MHz – AM
Sunday 1.4.2012 starting at 08.00 utc.

10) MIKE RADIO, Holland – around 21.500 MHz – AM
Not 100 %. 21.500 or 21.850 MHz.
Antenna tower still down for the winter.

XX) RADIO BLACK ARROW, Holland – 21.490 MHz – AM
Transmitter broken week ago – Possibly not on air

11) RADIO FOX 48, Scandinavia – about 15.092 MHz – USB – 300 W
Saturday 14.00 – 16.00 utc.

12) CUPID RADIO, Holland – 21.460 MHz (or 15.065 MHz) – AM
Saturday 31-3 euro afternoon broadcasting towards the U.S.A freq 21.460 mhz [when the band is down 15.065]
Sunday 1-4 starting at 08:00 utc till 10:00 utc freq freq 21.460 mhz [when the band is down 15.065]
Sunday 1-4 euro afternoon broadcasting towards the U.S.A freq 21.460 mhz [when the band is down 15.065]
Loads of sstv pictures will be send out during the broadcast.

13) MUSTANG RADIO, Holland – 15.000 – 15.100 MHz – AM – 50 W
Again new participant! More info later!!

14) RADIO LATINO, South Europe – 15.000 – 15.100 MHz –
26.100 – 26.200 MHz – AM – 40 W
Salsa mix-programme (30 min) on early morning on Saturday and Monday
at 06.30 – 07.00 and 07.30 – 08.00 utc! Progamme will continue longer if possible.
-26.100 – 26.200 MHz (in the morning, if propagation helps)
-15.000 – 15.100 MHz (in the evening, if morning propagation is bad)
More info and realtime-info on the web-page: http://radiolatino.bigbig.com/
E-mail: radiolatino@live.com

15) RADIO UNDERGROUND, England – 15.000-15.100 MHz -USB – 80 W
More exact frequency and times later, also 21 MHz is possible.

16) FREE RADIO VICTORIA, Holland – 21.880 MHz – AM- 50 Watts
On Sunday 1/4/12 from 08:00 ….. 10:00 UTC on the Dipole intend for Scandinavia and the Mediterranean Sea.
On Sunday 1/4/12 from 11:00 ….. 13:00 UTC on the Vertical ant. intend for overseas country,s .

17) RADIO TROPIQ, Central Europe – Many frequencies – AM 50 W / LSB – 80 W
Saturday
15.00 – 15.30 UT 15.050 MHz
16.00 – 16.30 UT 11.450 MHz
18.00 – 18.30 UT 9.950 MHz
Sunday
08.00 – 08.30 UT 18.205 MHz
09.00 – 09.30 UT 9.950 MHz

North America
18) Radio True North – 15.460 MHz (200 W) or 21.850 MHz (40 W)- AM
On air from 14.00 – 23.00 utc.
Also possibly on air on 6.925 or 6.950 MHz around at 02.00 utc

OUT OF HF-FREQUENCIES:
19) COOL AM RADIO, Holland – 10 Watts mobile – 6925 or 6940 kHz
This station is NOT HF-station because it uses 42 mb but I
took this in because it is special 10 W mobile!!

PIRATES – ATTENTION!
Info of free frequencies can be found here:
http://www1.m2.mediacat.ne.jp/binews/bia12.txt

BASIC SCHEDULE

1) European MORNING 08.00 – 12.00 UTC from Europe to Asia/Japan/Oceania.

2) European AFTERNOON 12.00 – 16.00 utc from Europe to North America and vice versa.

3) European NIGHT 22.00 – 24.00 UTC from North America to Asia/Oceania.

Chinese Firedrake Jammer

Posted on by
1

Firedrake is the unofficial name of a shortwave broadcast featuring loud oriental orchestral music. It exists solely to jam other signals, such as broadcasts by Sound of Hope, which broadcasts programming from Taiwan that is often critical of Chinese government policies and human rights abuse. The broadcasts only contain music; no form of on-air identification has ever been reported. Apparently, the source of the Firedrake shortwave transmissions is a China National Radio satellite feed.

While international regulations prohibit jamming, this has never stopped China (or the Soviet Union, Cuba, Iran, etc) from doing so. Rather than use a traditional jamming sound, apparently China believes that transmitting music 24 hours a day on dozens of frequencies doesn’t qualify as jamming. Or that no one will notice.

Here is a recording of Firedrake from March 29, 2012 on 14970 kHz.

Below is a relatively current list of known Firedrake transmissions:

Frequency     UTC Time
6280          2200-2400
7105          2200-2300
7280          1100-1300
7310          1300-1400
7310          2300-2400
7525          2300-2400
7565          2200-2400
7615          2200-2400
7970          0000-2400
9200          0000-2400
9450          1400-1600
9540          0900-1100
9635          2200-2300
10300         0000-2400
10965         0000-2400
10970         0000-2400
11500         0000-2400
11550         1200-1300
11760         0900-1100
11820         1330-1400
11980         2000-1700
12130         1500-1630
12160         1130-1200
12175         1300-1330
12175         1600-1700
12230         0000-2400
12300         0000-2400
12600         0000-2400
12670         0000-2400
12980         0000-2400
13060         0000-2400
13130         0000-2400
13270         0000-2400
13500         0000-2400
13850         0000-2400
13920         0000-2400
13970         0000-2400
14400         0000-2400
14700         0000-2400
14900         0000-2400
14970         0000-2400
15070         0000-2400
15500         0000-2400
15745         1230-1300
15750         1300-1330
15750         1400-1500
15800         0000-2400
15900         0000-2400
15970         0000-2400
16100         0000-2400
16700         0000-2400
16980         0000-2400
17100         0000-2400
17250         0000-2400
17450         0000-2400
17560         1400-1430
17920         0000-2400
18180         0000-2400