Originally Posted by
DaveLeeNC
Is that how things typically work?
Yup (basically). Well-described (by you) too.
The important thing that you might be missing is that the data is being sent in
packets.
Originally Posted by
DaveLeeNC
1) When the sensor is alive it is sending both ID (and other if it is required) information that allows the head unit to distinguish it from the other devices on your bike, devices on other bikes near you, noise/crap that exists in the 2.4 GHz range, etc
For
networks (where you have multiple devices talking to other devices on the same channel), information is sent as "packets".
These packets are marked with something that identifies the sender and (often) the receiver.
This is very analogous to letters mailed in envelopes that have two addresses (the sent-to and sent-from addresses).
For the typical ANT+ sensor, the packets being sent are being
broadcasted (where there is no specific receiver). For something broadcasted, the packet isn't marked with a receiver.
This broadcasting is analogous to radio stations where the station sends stuff out whether or not anybody is listening but you have to tune-in (pair) to a particular frequency to listen to the data.
The paring process looks at the send-from addresses in the packet (ignoring the contents of the envelope).
ANT and Bluetooth are light networks (sort of like what the internet/wifi uses but not as heavy-duty or robust).
"Handshaking" is a synonym for pairing (usually for two-way communication).