Sunny Days in London are Rare… and a Great Excuse to Geek Out with Some SDR!


During a recent business trip to Europe I had the opportunity to do a bit of sightseeing in London. I was also fortunate enough to visit on a warm sunny day, which has been a bit of a rarity this year. While walking through town, I realized that I had all of the components I needed to do some quick experiments with my SDR (software defined radio) near the important landmarks – Big Ben, the London Bridge, etc. This is a short write-up about my experiences in London, my stop on the “USRP World Tour”.

The technical details: I am running a slightly dated Lenovo laptop – a W520 with Ubuntu 13.04 to be exact. It has multiple USB 3.0 ports, an NVIDIA Quadro 1000M, and decent battery life. In my bag I also had a USRP B200, which is a full transceiver that covers 70 MHz – 6 GHz and runs on USB bus power. Bus power allowed me to get things going by plugging it into the laptop, without the need for external power.

Anyway, here are some pictures and notes about the experience!

The First Stop – Just Getting Warmed Up

In the background you can see the London Eye over the rooftops. To be perfectly honest, I had no idea what it was at the time, but it looked important. It turns out this is a prominent building along Whitehall, which is where a good portion of Her Majesty’s Government is housed. I ran some fairly simple applications – like GPU-accelerated FFTs with gr-fosphor and some FM demod. I could have run more complex things like an LTE eNode-B or OpenBTS, but I figured “The Fuzz” wouldn’t be too happy about unlicensed transmissions so close to the VIPs of Parliament. As you can see the camera on my tablet isn’t too stellar. I wonder if anyone from the local government happened to get some higher res pictures of my setup!



Curious On-Lookers

This is probably one of the more interesting points of the journey. I had parked the laptop in front of Big Ben to take some pictures and check out some spectrum. I was the recipient of many curious and suspicious glares. And then something very interesting happened. Some pedestrians stopped to talk to me. “What are you sniffing?” they asked. It turns out that one of the gentlemen had some SDR experience and was also familiar with GNU Radio, and OpenBTS. I found this extremely interesting. The fact that a random person on the streets of London recognized and showed interest in GNU Radio is a major sign of progress for the USRP, GNU Radio, and the concept of SDR in general. In any case, they were thirsty for more information and it just so happens that I am “one of those marketing guys.” Naturally (or perhaps unnaturally?), I had my slide deck ready to go right there in the middle of London. They were impressed with how far SDR and wireless technology has come.



The Cliché Phonebooth Pics

Some tourists from France were kind enough to help me out with these nice cliché shots!




SDR On the Backdrop of Peaceful Protest

I packed up and started walking up the street a few more blocks. Odd thing though… There was a police helicopter and several other vehicles in the vicinity following me up the road. I knew it was unlikely, but in the back of my mind I wondered if those suspicious looks I received near Parliament translated into worried phone calls to the authorities. As I turned the corner I was relieved to find myself in the middle of a protest marching on Parliament and thought, what better time to setup for some more GNU Radio development in the midst of peaceful protest! (Although I never figured out what they were protesting.)




Closing Thoughts

Software defined radio is more accessible than ever. Although this was a spur of the moment kind of thing, with some prep work and planning I could have tried some more interesting SDR applications. Mixing amateur photography with cutting edge SDR technology is a fun way to demonstrate the power of this enabling technology and how wireless innovations touch nearly every aspect of the world around us.

So I wonder – where else in the world are USRP devices being used? The Eiffel Tower? A pleasant beach? Please share your adventures with us! Please take your own photos and tell us about how you are using your USRP. Please link to or post them on Twitter and include hash tag #USRPWorldTour ! We’ll retweet them from @EttusResearch and aggregate them on the Ettus Research blog.

Also, use your USRP responsibly so that you don’t end up in an episode of “Locked Up Abroad“.