6 ways of monitoring who is at home

I ran across this article



Unfortunately there is no good method of discovering devices being in non-discoverable mode. However, it is possible to detect a specific device if its bluetooth address is known. It can be done by opening a connection to the device. There are two challenges with this approach:

1) different devices implement different features and a device can be detected only if it listens on the PSM (bluetooth port) we are trying to connect to,

2) any connection attempt on a non-paired device results in a confirmation dialog displayed on the detected device which must be accepted by the user to let detect the device.

Both issues can be solved by taking advantage of the fact all bluetooth devices should implement SDP (Service Discovery Protocol). SDP itself is implemented on top of low level L2CAP protocol, it listens on PSM == 0x01 and connections to it do not require to be accepted by the device user.

This approach has been successfuly implemented in BlueRadar.

Seems to me that this might be a good method for proximity detectors. It could scan for a specific phone that wouldn't need to be pairs to the PC now have Discovery on.