Microsoft shows how to crowd-source spectrum management
You do have a spare analyser, don't you?
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Researchers from Microsoft have proposed a new way to monitor spectrum usage, by connecting up idle analysers and providing an API allowing anyone to make use of them.
The concept of SpecNet, as the researchers term their creation, is to link up spectrum analysers around the world and allow them to be accessed through a standard API so that a company, government, or individual, could run a query to see who is using what and where.
But the complexity is in putting that all together; creating software to manage programmed queries and keeping it simple enough for general use, while maximising the application of spectrum analysers, which are expensive bits of kit rarely used to their full potential.
SpecNet addresses the technical problems by creating APIs of different complexity dependent on the class of user – so the high-level API could be used to establish the occupancy of a band within a specific geographic area, while a different API is used to monitor for transmissions of a specific shape or power. SpecNet takes care of distributing the task to the right analysers and gathering historical data, while dealing with the fact that analysers will disappear for extended time periods while the owner is using them.
The researchers present answers to these problems (in PDF/557 KB form – really interesting but quite specialised), as well as addressing the balance between granularity, fidelity and time that spectrum-scanning demands (the more carefully you look, the more you'll see). What they don't address is the political side of the problem.
A worldwide network of spectrum analysers is a nice idea, but as the researchers admit, it's not easy to convince labs and research establishments to connect up their $10,000 bits of kit to the internet for everyone else to use. Even if that can be addressed, there's the problem that many analysers spend their lives in basements or Faraday cages (or even down salt mines) specifically to avoid picking up local radio signals. But ignoring the political practicalities for a moment, it is worth thinking about how useful SpecNet could be.
A national map of radio usage in the UK would cost about £2.11m annually to maintain, according to CRFS, which carried out a trial run for Ofcom in 2009. That proved too rich for our regulator's blood, but did attract the attention of the FCC, which plans to spend more than $10m to create a map of the USA as part of the country's National Broadband plan (mainly to aid the search for more spectrum to sell off).
The Microsoft chaps do hopefully suggest "governments may be willing to sponsor a set of spectrum analyzers dedicated for SpecNet use", and it would certainly seem to be an effective alternative to CRFS's method of strapping spectrum analysers to the roofracks of travelling salesmen.
As we exploit radio spectrum with greater efficiency, there is more interest in knowing just how efficiently we are exploiting it, and if there are any bits we've missed; SpecNet might not be the answer, but it's an interesting step towards it. ®
COMMENTS
You don't need "spectrum analyzers"
This can be done very cheaply with direct conversion DSP receivers for way less than $10k each. WinRadio, ICOM, Ten-Tec, and others all offer black box digital receivers, already equipped to network (verb). These provide real time full spectrum radio surveillance to intel communities. Most spies work for taxpayers (or Microsoft) so shouldn't the public have access to it?
Mister Softee is again trying to reinvent the wheel.
I've just suggested to my team that we might contribute
Thanks Bill for finding this, we do have a few SpecAnals lying around, they're nearer €75k and are unused between lab tests. I'm a bit concerned about plugging & leaving them into a real antenna (I have a 25MHz to 2GHz discone outside the lab), as summer is thunder & lightning season!
I used to use an atomic clock controlled HP spectrum analyser attached to a long wire antenna to listen to international shortwave radio during the 1980's when I worked in a faraway desert where shortwave receivers were forbidden, HZ. I wrote to Swiss Radio International with a screen-shot informing them that their 17MHz transmitter was a whole 100Hz away from their published frequencies.
Always buy a spectrum analyser with (now digital waveform) demodulator and loudspeaker!
hmm
Well, I could probably identify at least half a dozen spectrum analysers in London alone, most of which are idle for over 80% of their lives. They are not placed to avoid local signals they are just not connected to anything useful in they way of antennas. The issue would be finding antennae of sufficient bandwidth and gain to meet the needs of such a survey. But more significantly there is no standard protocol for controlling spec analysers, downloading over serial or going us stunningly slow on most kit I have used. That is if even the output can capture the spectrum or if it is only practical for control. The most consistent output us, oddly enough, video (cvbs).
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