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Monday, December 12, 2011

The dollars and cents of a software defined scanner radio

It's feedback time again! I've had some more questions about the scanner stuff, like details of pricing. Here's the scoop.

The production system as it stands now is an Ettus Research USRP1 with a DBSRX2 board in it. I picked the DBSRX2 initially out of relative ignorance because it would cover the 850 MHz frequencies I needed for Santa Clara.

Just that right there was $700 for the USRP1 plus $150 for the DBSRX2 receiver board. On top of that, I had to upgrade the hardware on my existing Linux box to keep up with it. My 2006 vintage hardware was not nearly enough to deal with processing 128 Mbps of data from the USB bus in real-time.

I get about five years out of a workstation in general, so it was time to move up anyway. The new CPU, case, motherboard and memory cost almost $600. This system is ridiculously fast and should hopefully last another five years.

So right there, we're looking at about $1450 just for the hardware. Then there's the matter of my time to develop the software, and I'll just say that I'm not cheap when it comes to my time and effort. It's expensive but you'll never be disappointed.

It becomes painfully obvious that only the most dedicated people would ever buy one of these things for themselves. It seems far more reasonable that people who wanted to listen would just subscribe for a monthly fee. I am set up with PayPal to accept credit cards for exactly this situation. Anyone who wants to escape from the realm of the demo account can just subscribe.

What are the alternatives? Well, you could listen to the existing streams and put up with the issues I described last week.

Alternatively, you could go out and buy your own scanner. A high-end Uniden model will cost you about $500. It will handle trunking, but you still only get to hear one channel at a time -- concurrent calls are lost forever. You also don't get any sort of recording ability with that. If you want to be able to review things later, you have to arrange your own recording system. This, too, is subject to the limitations described before.

The only way to do the "record in parallel" thing with a scanner is to have a bunch of them. You'd need one scanner for each simultaneous call you want to receive. Then you also need to rig up some kind of multi-input recording device which will keep all of this intact somehow. Just how many line-in ports does your PC have? Mine has just one.

Oh, also, you have to figure out how to make sure two scanners don't stop on the same call. This can be tricky if you're monitoring a trunked system!

The magic in my setup is that I've already dealt with all of this gunk for the Santa Clara system. If all you want to do is listen, it Just Works.

Compared to all of this, just subscribing seems far easier.

Random hardware nerd note for those who care: as beastly as this new machine is (/proc/cpuinfo says "Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz" for those who know these things), running the Santa Clara system stuff is still no small thing. It stays around 7-8% utilization 24 hours a day due to the workload.