×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Medtronic CGM App

Medtronic CGM App

Medtronic CGM App

(OP)
My son wears a Continuous Glucose Monitoring (CGM) device, http://www.medtronicdiabetes.com/treatment-and-pro... http://www.medtronicdiabetes.com/treatment-and-pro...

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/sites/default/fil...

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

RE: Medtronic CGM App

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.

RE: Medtronic CGM App

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!

RE: Medtronic CGM App

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.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources