US and Cuba set to re-establish diplomatic relations: the shortwave radio listener perspective

Sunday, December 21, 2014
Viva Cuba by Alain Bertrand
On December 17, US President Barack Obama announced a "new chapter" in US relations with Cuba with a move to re-establish diplomatic and economic ties between the two former Cold War adversaries. Though much has already been written about this elsewhere, I would like to share my perspective of this event with a few shortwave recordings I made the following morning.

Readers of my blog and Twitter feed know that I'm big fan of Cuban radio. However, because this was a White House announcement, I wanted to hear the official US perspective on this historic event. I tuned into the Voice of America broadcast, directed at Africa from the Vatican (6080 kHz on 18/12/2014 at 0259 UTC):

The style and the delivery of this news bulletin combined with the magnitude of the events being mentioned reminded me of catching the tail end of Cold War shortwave broadcasts as a small child in the late 1980s. Another news item that stood out for me was the unilateral declaration of ceasefire by Colombia's FARC guerrilla group. It left me wondering whether this was somehow tied to the US-Cuba announcement, as negotiations between the rebels and Colombia's government have now been taking place in Havana for quite some time.

Shortly before that, though, I tuned into Radio Martí, the clandestine broadcaster funded by the United States government that transmits American propaganda newscasts and programmes in Spanish to Cuba (check out my earlier post for a quick profile of this station). Although I would not normally turn to them for any in-depth analysis (or to any clandestine station for that matter), I was very curious to hear how they would present this tectonic shift in the American policy towards the island nation, given how scathing they normally are of the Cuban regime as a whole. Below is my recording of Martí's news bulletin transmitted from their Greenville transmitter in North Carolina (7365 kHz on 18/12/2014 at 0059 UTC)

Unsurprisingly, the news of the re-establishing of diplomatic relations was quickly followed by criticism of Obama by senators Menendez and Rubio, who said that it was too bold a move and that consultation with the US Congress would be necessary before any real progress could be made. However, it is unlikely that many Cubans would have heard their complaints, as my friend Thomas Witherspoon at tells me that the Cuban jamming of Martí's signal is so strong that he can barely copy it at his home in South Carolina. It is somewhat ironic, then, that I can receive it better here in London.

On the other hand, my attempts to record Radio Habana Cuba that night were far less successful. Propagation was really weak on the 49 meter band, which, combined with a number of sources of local interference made it very difficult to tune into either the Spanish broadcast on 6060 kHz or the English one on 6000 kHz. The speech was intelligible but the reception conditions certainly didn't help to make nice recordings. I was briefly lucky around 0325-0335 UTC on the latter frequency and was even able to record their half-hour news bulletin (which unfortunately was condensed and didn't cover all the key events of the day), but by its end, the local noise source had returned with a vengeance. Still, at least I was able to record some nice music!

Luckily, Thomas at made a full one hour recording of that broadcast in superb audio quality. I embed it below with his kind permission (6000 kHz on 18/12/2014 at 0300 UTC).

Predictably, the main focus of the news was on the release on the remaining three of the Cuban Five and less on the re-establishing of relations itself. However, the broadcast also contained the English translation of Raul Castro's speech that coincided with Barack Obama's announcement. Gerwyn Jones's commentary on the Islamic State (20 minutes into the program) was also noteworthy. And here's a bit of trivia: the music at the start of the recording is Bailando Suiza by Harold Lopez-Nussa Trio and David Sanchez. All in all, it was definitely one of the more exciting days to listen to shortwave radio.


My submission to Virtual Radio Challenge II

Sunday, September 28, 2014
Update (15/11/16): this article describes an older version of my portable SDR configuration. Jump to this post to see my current set-up.

A few days ago The SWLing Post published a challenge to their readers: given a budget of $1200, to put together the best possible shortwave radio listening set-up that can function completely off the grid in the Himalayas.

My solution is to fuse my two previous submissions to The Post - my response to the shortwave listening challenge for the remote Atlantic island of Tristan Da Cunha and my portable SDR design - and to add solar power.

FunCube Dongle Pro+ and Toshiba Encore 8" running SDR# in a London park
To recap, the tablet-based SDR set-up costs $643. My experiments with FunCube Dongle Pro+ and SDR# software have convinced me that this combination makes for one of the best shortwave listening experiences in its price range. Here are a few reasons why:

FunCube Dongle Pro+ is a sensitive SDR.
- SDR# has an excellent noise reduction algorithm that often turns laborious DXing into comfortable listening. It also has a robust synchronous detector, which, combined with its passband tuning and noise reduction algorithms can unbury almost any station from the surrounding co-channel interference.

However, given the remoteness of the location and the fact that there is no reliable electricity grid to speak of, we need a few extras:

Solar Power

You may recall that in my portable SDR solution there are two sets of batteries that need to be recharged:

- Toshiba's built in Lithium Ion battery (via its USB port)
- 4xAA batteries for the Gomadic 5V Power Pack (used for supplying extra power to the SDR)

First, let's get a compact, foldable solar panel:

1. Powerfilm F16-1200 20W foldable solar panel

I would go with Powerfilm F16-1200 20W foldable solar panel  (buy it here for $210.99). Disclaimer: although I've never used any of the PowerFilm products or accessories, I have read good reviews of them from other radio enthusiasts. When folded, this solar panel measures merely 27.9cm x 16.5 cm - slightly smaller than an A4 notepad. Once fully opened, however, it can deliver 20W of power (15.4V, 1.2A), enough to charge the Toshiba tablet and 4xAA rechargeable batteries simultaneously.

To charge the AA cells, I would go with the Powerfilm RA-3b - 12V Battery Charger Pack for AA and AAA (buy here for $54.41) and the Powerfilm RA-2 12V Female Power Port Adapter (already included with F16-1200).

2. RA-3b - 12V Battery Charger Pack for AA and AAA

3. RA-2 12V Female Power Port Adapter

Although we only need 4 AA batteries for the Gomadic USB Power Pack, it's always nice to have some spare ones, just in case. I would throw in a pack of 12 Panasonic Eneloop AA 2100 Cycle Ni-MH Pre-Charged Rechargeable Batteries for $26.95.

4. 12 Panasonic Eneloop Rechargeable Batteries
The spares can be used in the following ways:
- To power the backup portable shortwave radio
- To have another batch ready when the batteries insde the Gomadic USB Power Pack run out.
- Using Gomadic, to charge the tablet outside daylight hours, for more daytime listening.

Now onto charging the tablet itself. For this I would use the Powertraveller Spidermonkey 4-Port USB Charger Hub at $38.76. Again, I haven't used this product, but according to the specifications it can charge up to 4 USB devices and accepts input power between 5V and 30V. The reviews are largely positive, so it seems like a safe choice.

5. Powertraveller Spidermonkey 4-Port USB Charger Hub
To connect the Spidermonkey hub to the solar panel we'll need the Powerfilm RA-16 - 3ft. Extension Adapter with 4.75mm Barrel cable (available here for $9.98)

6. RA-16 - 3ft. Extension Adapter with 4.75mm Barrel
If we want to charge both the tablet and the AA batteries simultaneously, the  Powerfilm PP-7 - Multiple Device Charger Cable accessory will come in handy (here for $24.99)

7. PP-7 - Multiple Device Charger Cable

Antenna Extras

Living off the grid has the advantage of there being minimal man-made radio interference. For this reason we can use a larger antenna than in my original proposal. I suggest buying 40m of POLYS18 Copper-Clad Steel Antenna Wire from Universal Radio (the total comes to $31.44), cutting it halfway, and attaching each half to one of the two antenna terminals on the Wellbrook HF Balun, mentioned in my previous article, thus creating a dipole.

Of course, this makes for a rather powerful shortwave receiving antenna that can easily overload the radio. We can solve this problem by connecting the balun's feedline output to the antenna terminal on the Global AT-2000 Antenna Tuner, $85 via 25 feet of GadKo BNC Male Copper Stranded Center Conductor Cable , $16.90. We should then connect the radio terminal to the short feedline cable of the FunCube Dongle Pro+ SDR, with the ferrite chokes left in place. We will need 2 x BNC female to PL259 Adapters, $6.49, to connect the BNC cables to Global's PL259 female sockets.

8. Global AT-2000 Antenna Tuner
9. 2 x BNC female to PL259 Adapters
10. GadKo BNC Male Copper Stranded Center Conductor Cable

Finally, here's a simple schematic diagram of how the antenna parts should be wired together:

Connecting all the antenna bits together

Backup Radio

The challenge article mentions that a back-up radio would be desirable in the event of other equipment failing. I suggest Tecsun PL-310 ET, available for $48.79 from Amazon. It's a very similar radio to the excellent Tecsun PL-380 (they use the same Silicon Labs chipset), but it has one notable advantage: an external antenna input! It takes a 3.5mm jack plug, so we'll need a BNC Socket to Composite 3.5mm Male Jack Plug Adapter, $2.01.

11. Tecsun PL-310 ET
12. BNC Socket to Composite 3.5mm Male Jack Plug Adapter 

The subtotal for all of the above comes to $556.71. Adding on $643 for the tablet-based SDR solution brings the total to $1199.71, just 29 cents below the budget limit!


Designing a portable SDR system

Sunday, August 24, 2014
Update (15/11/16): this article describes my initial portable SDR configuration, which is now substantially improved. Jump to this post to see my current set-up.

This article is a follow up to the submission I made to the SWLing Post a little while ago. In short, the idea was to combine the FunCube Dongle Pro+ USB-based software defined radio (SDR) with an 8" Windows tablet running SDR# to have a portable, on-the-go SDR solution.

The original inspiration

Tablet radio interference

At the outset, I thought that all that was necessary was a tablet (I chose Toshiba Encore 8"), the FunCube dongle itself and just some antenna wire. This turned out to be a naive assumption because the tablet's USB interface injected enormous amounts of radio frequency interference (RFI) into the SDR, making listening on some shortwave frequencies essentially impossible. Just to be sure that I wasn't being plagued by a defect of my chosen tablet model, I tried out the same set-up on a Dell Venue 8, with identical results.

To deal with the issue of tablet-generated RFI, I bought a galvanic USB isolator, which, in essence, is a box that breaks the electrical connection between the USB dongle and the tablet's USB interface while allowing USB data to pass through in both directions.

Heros Technology galvanic USB isolator

Additional power for the SDR


The isolator resolved the RFI issue completely, but created another problem altogether: the device specifications state that the isolator's power output is restricted to 100mA at 5V. This is sufficient for USB devices that are self-powered but not for the FunCube dongle that draws all of its power from the USB port to which it is connected.

USB Y cable
One way to supply extra power to a USB device is to use a "Y-cable". Such cables have one extra USB plug that can be attached to a source of additional power (for example, a USB power bank). This solution is commonly used to connect power-hungry items, such as large hard disks, to low-power, portable computing devices (laptops and tablets). Having bought this cable, my next step was to find/improvise a battery that meets the USB power specifications (5V, 500mA).

Yet more interference

My first thought was to use the mobile USB power bank that I use to charge my iPhone while on the go. After all, it already has a USB port and supplies power with the right voltage. Once again, my expectations were confounded and RFI reared its ugly head! The power bank radiates significant interference into the circuit because it uses a switching regulator to maintain steady voltage. Luckily, I came across Gomadic's portable AA battery pack with regulated 5V output that emits way less interference than any of the other USB batteries I tried (my intermediate solution used 4 rechargeable AA batteries and a makeshift USB connector, and although this resulted in zero additional interference I decided that it's not safe to supply the SDR with unregulated voltage that doesn't match the rest of the circuit). I used the handy passthrough USB voltmeter I bought in Maplin to check that Gomadic's nice-looking gadget does indeed give out 5V as advertised.

So, what can one do with the remaining RFI from the additional power supply? It turns out that it can be mitigated quite effectively by inserting a balun (item 10 on Figure 2) between the SDR and the antenna wire (item 12). The balun is connected to the SDR with a coaxial cable (the "feed line", item 11). Additionally, ferrite choke rings (item 9) attached to the feed line help reduce this RFI further: winding the feed line through the choke rings several times is sufficient. However, neither the balun nor the chokes are effective enough to replace the USB isolator! It appears they only help with the noise generated by the power supply, which is relatively minor anyway.

Cost vs Portability

When SWLing Post published the details of my intermediate solution, Dennis Walter - one of the engineers behind Bonito RadioJet - popped up in the comments section and suggested that my setup is too tedious, as it involves lots of cables, and that his SDR is superior in terms of portability and the supplied software. While I haven't had the chance to evaluate RadioJet, I pointed out that the cost of his radio is significantly higher than that of all of my components put together. I also mentioned that the free SDR# software I use is superb: it sounds excellent and offers a number of features that many software packages and conventional radios don't have. So, having finalised my design, I thought that it might be time to tally up the cost and listen to the results.

Below is the full component list:

11) Feedline cables $7
12) 6 metres of thick copper antenna wire: $8

Adding up the prices of items 2 - 12 (and excluding the optional voltmeter) brings the total cost to  $449 vs. Bonito RadioJet's $689. For the price difference you can throw in the Toshiba tablet at $194 and still have some change, enough to buy a carrier bag and perhaps even a nice pair of headphones!

Figure 1. Radio components
Figure 2. Antenna components
In terms of portability, the entire setup fits nicely into an 11" laptop carrier bag.

Figure 3. Packing the components into an 11" carrier bag

Figure 4. Ready to go
Setting things up in the field is not particularly cumbersome, either:

Figure 5. Portable SDR setup in action in a local park
As for the results, listen to the below snippets and be the judge. The only thing I will say is that none of my other portable radios have ever given me this kind of performance, not even with the long wire antenna attached:

And while we're at it, here's a demo video:

At one point I wanted to build an enclosure to house the FunCube dongle, the power supply and the USB isolator in a single tidy unit, but I no longer see the need. It's easy to pack all of those items into the carrier bag and also they are all useful individually: the USB isolator can be paired with other SDRs, and I recently discovered a neat additional use for the Gomadic battery pack.

Well, that brings me to the end of this post. I hope my design will inspire you to come up with your own portable SDR system, and that you will share your results with me in the comments section. Happy listening!


Portable operation of Newstar DR111 DRM receiver

Saturday, August 23, 2014
NewStar DR111 is one of the few commercially available consumer DRM radios. In my experience, the radio works quite well with an external antenna (such as the Wellbrook ALA1530 magnetic loop).  However, one of the main drawbacks of this unit is that it doesn't work off batteries, making portable operation cumbersome. The built-in whip antenna is long and has demonstrated fair performance in the past, but indoor reception with it is typically hindered by local radio frequency interference (RFI).

Radio enthusiasts have engineered some ingenious workarounds for this problem. For example, Alokesh Gupta used a DC-AC inverter to power the receiver's wall-wart 5V DC adapter from a 12V car battery, while Tudor Vedeanu improvised a portable AA battery pack that connects to the radio via a DC plug. Both methods are awesome hacks, but the former is quite power-hungry, while the latter only allows rechargeable batteries to be used (four alkaline AA batteries will supply well over 5 volts and this creates the risk of radio damage).

Although I bought my DR111 almost one year ago, it hasn't been getting much use; in the table-top / external antenna setting, software defined radio applications allow for excellent DRM reception. However, yesterday I discovered one undocumented feature of the unit that makes portable operation really easy: it turns out that DR111 can draw power via its USB port!

NewStar DR111 DRM receiver connected to Gomadic AA battery pack via the USB port
Enter the Gomadic Portable AA Battery Pack with regulated 5V output and its USB connector accessory. No risk of power overload and no need to solder wires and plugs together. Below is a video of DR111 running on four AA alkaline batteries in a local park earlier this morning:

While in DRM mode, I enjoyed listening to Radio Exterior de España and Radio France International (the latter being especially impressive as its signal is rather weak and the time of day didn't allow for good propagation on the corresponding frequency). I also tuned into the final hour of Radio Habana Cuba's morning analogue shortwave broadcast.

One important thing to note is that while there are other portable USB power solutions out there, some of them inject quite a bit of RFI into the receiver because of their switching voltage regulator design. Fortunately, in the case of Gomadic, this artefact isn't too strong and doesn't get in the way of decent radio reception. I look forward to listening to All India Radio's afternoon DRM broadcast on 15140 kHz later today and perhaps I might even catch Radio New Zealand International's DRM signal like this shortwave listener did!