Need advice on scanning 2.4ghz with Arduino

[Molten Fungus]

Overview
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My daughter was recently diagnosed as a type 1 diabetic, and recently acquired a DexCom Continous Glucose Monitor (CGM). The CGM consists of a sensor, transmitter and receiver. According to their Spec, they broadcast in the 2.4Ghz range and even specify packet sizes. Though the monitoring tech is awesome, the interface is pretty sad. For example, I would like to be able to use a smartphone instead of that handheld device they sell, and if possible, send a text to either mine or my wife's cell phone (I would need to get up to speed on writing an app..but that's not the issue) when she's in school. Also, instead of having a phone and this receiver, in my mind it should be one device. ( I have more ideas that would make life much easier, but this is an overview)

So..being an Arduino fan (mega and uno with Sainsmart stuff), I was wondering how to get started with the above project. I've already figured out how to decipher IR with some of the papers on this site, and I'm wondering if this is something do-able, and if so, what hardware would I need to get started.
Basically, to get started, I'd like to see the packets coming in from the transmitter and try to figure out what's going on.. I don't have protocol specifications.

If I'm just being naive, let me know.

Thanks ahead of time.

[janekm]

Unfortunately there is not as much protocol standardisation at 2.4GHz as with IR, so you don't have a realistic chance of decoding the signal without knowing what protocol is used.
A good start is usually taking apart the device and figuring out what radio chip is used (I'm not recommending that in this case as it's a medical device).
Even if you know the chip, many chips support multiple encodings and protocols. And if you're really unlucky they may be using an encrypted link too.
Here's a great blog about reverse engineering radio protocols: http://travisgoodspeed.blogspot.co.uk/?m=1

[Molten Fungus]

Thanks..
I'm scanning the blog now..There's no way I would even attempt at opening up the transmitter..

The actual packet being transmitted is 240 bytes, 6 of them being the transmitter ID..
The information (I'm guessing) is some numerical value, which is used by the receiver where it does all it's calculations..
well.anyway...it's a challenge..

Thanks for the info.. I just needed some quick path to get started..
Really do appreciate the response.