Medtronic CGM App

[RonShap]

My son wears a Continuous Glucose Monitoring (CGM) device,

http://www.medtronicdiabetes.com/treatment-and-products/continuous-glucose-monitoring

http://www.medtronicdiabetes.com/treatment-and-products/enlite-sensor

We can download metering information from the insulin pump direct to a receiver attached to the USB of my laptop, which includes CGM information from the embedded electronics transmission within the unit. The reiver is likely just converting frequencies for the USB. There is information related to the transmission frequencies toward the end of this user guide.

http://www.medtronicdiabetes.net/si...stem-Manual_Final_8-27-13_Mp6025813-012_a.pdf

Can anyone suggest how to take this information / frequency into a smartphone for remote monitoring?

I know that the manufacturer is working on this but they are limited to releasing their information until after FDA approval. The FDA might delay this several years although they put it in the media so it sounds like it is next week.

Being that I'm in the electrical power industry, and originally was educated in electronics, I thought maybe I can put something together in the meantime.

Suggestions are welcome. I'm a pretty good researcher once I have a lead.

Ron

 

[VEBill]

Hacking into one's medical devices isn't something that could possibly recommended. But presumably this is receive only, and you don't act on any potentially corrupted information without using the manufacturer provided system to cross check. etc. etc. ...endless disclaimers go here...

--

I wasn't able to open the pdf file, but I assume that the CGM system uses frequencies and protocols that would be outside the inherent capabilities of consumer devices. So the USB receiver is probably mandatory.

Many smartphones and tablets provide an "OTG" (On the go) facility where their little micro USB port can be put into Host mode by means of an appropriate OTG cable. The OTG cable contains a resistor or jumper or something to switch the device's USB port to host mode. Then you just (LOL) need the driver and application software. It becomes a software project.

There might be complications such as power consumption.

 

[LiteYear]

Sounds like there are two communication sessions available - from the transmitter (attached to the sensor) to the pump, and from the pump to the laptop. From what I can see, both use the proprietary 900MHz "MWT1" protocol. The frequency is certainly available to standard RF electronics, but the protocol is a whole heap of unknown.

There's an enormous range of possibilities, from modulation techniques to data encryption, and the likelihood of being able to decipher it just by monitoring the spectrum is low. If you could get some insight from the manufacturer to get you started, or even had some suspicion about how it might work, then it might be worth getting a 900MHz receiver and snooping in.

Otherwise, VE1BLLs suggestion of piggy-backing on the USB receiver might be more feasible. Even then, without some hint at what language is being spoken by the USB device, it's a huge domain of don't know. The USB receiver might just appear as a virtual COM port, and therefore maybe you could snoop on the traffic it sends, but it could also be a proprietary USB device and you'd be developing a custom driver with your eyes closed.

If you have an enormous amount of time to devote to this and an unwavering hacker mentality, then by all means start snooping. Otherwise I think you might need a leg-up from the manufacturer to get started!

 

[VEBill]

Another option comes to mind. The $10 to $15 price class (eBay) DVB-T RTL2832U + R820 "software defined radio" USB sticks. They cover about 45 MHz to nearly 2 GHz. They also can plug into any Host USB port, including some smartphones and many tablets (with OTG mode). Then you "just" (LOL) need the software, and there is a vast amount of information on the 'net on how to program them. Many an unknown signal has been reverse engineered by dedicated hackers.

(An even better option using the same sort of approach is to let other folks do all the work, and you just download their resultant SDR freeware once it's been released. I'm not exactly joking...)

These SDR DVB-T USB sticks typically come with a horrible little antenna that is likely to fall apart in your hands. So for serious projects, order several different versions and a handful of the MCX to something (anything) else RF adapters. Budget about $100, even though the sticks themselves are sometimes available for as low as $7 with free S&H. Because they're so cheap, they break easily. If you're handy with a soldering iron, then you can hack the hardware into something more rugged.