Category Archives: Travel

Radio Australia: SWLing in the Colorado Rockies

I’m in Keystone, Colorado at about 9,300′ (2,835 M) above sea level; mornings are crisp and chilly (38F/3C), but that doesn’t stop me from putting on a jacket, heading to the balcony and listening to Radio Australia on 9,580 kHz. Despite flaky solar conditions (flaky, frankly, is an understatement) I managed to snag RA Wednesday morning (13:58 UTC) on my Sony ICF-SW7600GR. There was a little fading, and a little local noise, but overall signal quality was quite good.

This recording starts a couple of minutes before the top of the hour; you’ll hear the TOTH news brief and then triple j—a brilliant show dedicated to new Australian music.

Click here to download the recording as an MP3, or simply listen via the embedded player below:

London Shortwave refines his tablet-based portable SDR

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One of the great things about the SWLing Post is that readers share their varied–and highly creative–methods of playing radio. A few weeks ago, SWLing Post reader, London Shortwave, shared his portable SDR set-up with us; he uses this outdoors to mitigate London’s heavy radio interference. Dennis Walter, president of Germany-based Bonito, commented, and later posted an alternative portable SDR solution using the Bonito RadioJet IF receiver.

Below, London Shortwave shares a guest post (also viewable on his blog) which describes in detail his design for his portable SDR around the FunCube Dongle Pro+ and an 8″ Windows tablet, and explains how effectively it works for him. This post includes recordings and a video; it’s an excellent tutorial:

DESIGNING A PORTABLE SDR SYSTEM

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

Connections

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:

1) Toshiba Encore 8″ tablet $194

2) On The Go USB host cable for Toshiba’s micro USB connector: $7

3) Heros Technology USB Isolator: $125

4) USB Y cable with two males + 1 female plugs: $8

5) Gomadic Portable AA Battery Pack with regulated 5V output: $20

6) Gomadic female USB connector tip: $6

7) FunCube Dongle Pro+: $208

8) USB volt-meter (optional): $33

9) 2 ferrite choke rings: $10

10) Wellbrook HF Balun: $50

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:

listen to ‘Channel Africa received in London, UK’ on Audioboo

listen to ‘Radio Nacional da Amazônia received in London, UK’ on Audioboo

listen to ‘Zanzibar Broadcasting Company received in London, UK’ on Audioboo

listen to ‘Radio Australia received in London, UK’ on Audioboo

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

Portable SDR on Toshiba Encore 8″ Tablet from London Shortwave on Vimeo.

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!

SWLing in New Mexico: Radio Australia

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This morning, I was very happy to tune to Saturday Night Country on Radio Australia (9,580 kHz). RA’s signal was booming into Taos, New Mexico, where my travels have taken me this Saturday morning.

It was a welcome relief to hear RA; the shortwave bands have been in terrible shape the past three days or so. The ionosphere has been so disturbed that the only broadcasters I’ve been able to hear have been Radio Havana Cuba and a few domestic religious broadcasters.

I hope to take the CommRadio CR-1 out later today and perhaps test a couple of outdoor antennas…Stay tuned!

Picnicking and SWLing by the lake

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Yesterday, while traveling near Oklahoma City, I stopped by Lake Thunderbird State Park for lunch and a little shortwave listening.

Blue sky above, sparkling water below, and a tasty homemade lunch in an RFI-free environment were ideal conditions for portable SWLing. I used my little Tecsun R1212A which was easily packed in the picnic bag. Many broadcasters in the higher bands; most notably, Deutsche Welle’s Hausa service, which was quite strong.

As always, my motto: “Have radio, will travel!”

SWLing on a mountain with the Tecsun R1212A

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Last week we visited Mount Mitchell, the highest elevation in North America east of the Mississippi River.

We enjoyed a leisurely picnic at the mountain’s state park, and since I had a little extra time, I pulled out the Tecsun R1212A I carry in my messenger bag, and tuned to Deutsche Welle. Even though propagation wasn’t superb that day, the little Tecsun did a fine job pulling in a DW service targeting Africa.

My friend the Professor had convinced me to purchase the R1212A as an open-box deal Anon-Co listed several months ago, and I’m glad he did. Not only does it have great shortwave sensitivity, but it has superb AM (medium wave) reception–indeed, it’s one of the best portables I have that can null out unwanted MW signals.

The Tecsun R1212A is no longer produced, but occasionally they pop up on eBay (click here to search for one).

Anyone else have this little portable?

Shortwave Radio Recordings: BBC to the 2014 British Antarctic Survey

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As promised, here are the recordings of the BBC World Service’s thirty minute broadcast to the British Antarctic Survey. The broadcast started at 21:30 UTC on June 21, 2014 and was broadcast on 5,875, 5,985, 7,350 and 9,890 kHz.

As in previous years, this broadcast was lighthearted, filled with humorous shout-outs from the team’s family and friends. Even a couple of special guests were included. Listen for yourself:

This excellent recording was made by SWLing Post reader, Dominik, in Europe:

Click here to download Dominik’s recording as an MP3.

Post reader Rob Wagner (VK3BVW), in Australia, could receive the broadcast on three frequencies (5,875, 5,985, and 7,350). He’s included clips of each broadcast on his excellent blog, The Mount Evelyn DX Report.

As for me, I was traveling to visit family yesterday afternoon when the broadcast started. I knew from listening endeavors on previous visits that receiving a broadcast indoors at their home is not feasible; there is some sort of power line noise in that area that overwhelms anything on the short or medium wave bands, unless the station is very strong.

To cope with this noise, I knew I would need to move my operation outdoors, away from the house, and employ an outdoor antenna. So I packed the following, all into my small flight case: the CommRadio CR-1, a NASA PA-30 15 foot passive wide-band wire antenna, and the Zoom H2n Handy Recorder
.

CommRadio-CR-1-Zoom-H2N-BBC-Antarctica

I hung the PA-30 antenna in a nearby tree, spread a wool army blanket on the ground for lounging, and put the mini flight case to use as a stand to hold the radio and recorder. The CR-1 required no external power supply, as its internal battery had been charged in advance (one of the reasons I love this little receiver for travel).

To try out the set-up, I tuned around the bands. Conditions were rough, thunderstorms were in the region, but I was most impressed that I could hear several broadcasters on 31 meters. I knew that the BBC broadcast would be a tough catch; after all, none of their transmissions were targeting my part of the globe–rather, the opposite!

When I tuned to the BBC broadcast on 7,350 kHz, here’s what I heard:

This is (very) rough copy; for five or so minutes, you’ll hear me switching between AM/USB and LSB to find the best mode for the signal. I also check the other BBC frequencies to see if any were more audible.

In the end, using ECSS (zero-beating the signal in USB) seemed to work best.

For fun, I had also brought along the Tecsun PL-660–a choice portable radio for weak signal DX. I tuned to 7,350 and could just hear the BBC signal in the noise, but voice and music were unintelligible.

What did I get out of the experience? Good copy? Alas, no.

But there’s nothing like the fun of playing radio outdoors! Even though the copy was rough, propagation deplorable, and static crashes abundant, I thoroughly enjoyed the experience. Moreover, I was amused to note that while I listened (and sweated) outside in the very hot, muggy conditions of the American southeast, a few scientists huddled near the extremely chilly southern pole at that exact moment, were tuning in the exact same broadcast. It somehow made the heat bearable.

That’s the remarkable camaraderie of radio: truly, a wireless community.

Eric remembers SWLing while deployed in Abu Dhabi

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In an email last week, my good friend Eric McFadden (WD8RIF), mentioned the shortwave radio set-up he used while deployed in Abu Dhabi, United Arab Emirates back in the early 1990’s. I asked Eric for permission to post his email notes–not only did he agree, but he also found photos he took at the time.

Eric notes:

[F]or the Desert Shield/Storm, aka the First Gulf War, I took my Sangean ATS-803A with a doublet fashioned from two Radio Shack audio cables. The doublet was an audio cable with an RCA on one end and lugs on the other; I split the conductors all the way down to the RCA connector and it was almost the right length for a proper 31m dipole.

The feedline was an audio extension (+/- 25′) with a male RCA on one end and a female on the other end. The ‘803A had a proper RCA antenna connector instead of a silly phone connector. I hung the doublet between the peaks of two of our 10-man tents, the front of our tent and the back of our neighbors’. When the UAE winds ultimately broke the doublet at the RCA connector, I stripped the ends and made a random-length end-fed wire out of it.

Our tents had AC-power (and A/C cooling and heat-pump heat) and I’m pretty sure I powered the ‘803A from the “mains” instead of stuffing D-cells into the radio. D-cells were available in the little BX on the base, of course.

The three photos [above] are of my installation in our tent-city at Al Dhafra Airbase near Abu Dhabi, United Arab Emirates. I did deploy my 31m dipole here. These photos were from before the dipole broke and was replaced by an end-fed wire build from the pieces of the broken dipole.

[This photo] was from inside our “hooch” on the Lockheed Compound near Jeddah, Saudi Arabia. (Click to enlarge)

That ATS-803A was a great receiver. It’s only real flaw was its size and weight. The size, of course, allowed for a really fine speaker. I traded the ‘803A in at UAR when I bought the ‘7600G and the little active [AN-LP1 loop] antenna when we thought we were to be deployed to Kosovo[.]

Here’s text from my journal I wrote shortly after returning stateside:

“I found many interesting and exotic stations on my shortwave radio, a Sangean ATS-803A and a simple dipole antenna, but as the war progressed,
I settled on the BBC for their award-winning news coverage.”

Many thanks, Eric! I’m happy to hear such a good report of the Sangean ATS-803A–there are still many 803A’s on the used market (click here to search eBay).

Indeed, I just realized that while you were deployed in the UAE, I used the Radio Shack branded version of the ATS-803A: the Radio Shack DX-440 while studying French and living in Grenoble, France. The DX-440 delivered my daily dose of the Voice of America (the only English language news I allowed myself to listen to at the time). Since the VOA broadcast often coincided with meal time at the Université Stendhal cafeteria, I left my voice-activated Micro Cassette recorder in front of the DX-440 which was, in turn, set to turn on one minute prior to the VOA broadcast. It was an amazingly reliable arrangement. (Hard to believe that was over 20 years ago!)

Come to think of it, I’ll have to dig up those micro cassettes and see if I still happen to have one with a recorded broadcast.