ANT Forum

If I read the code (antfs.c) correctly, it appears that I can set up my device to use a beacon period of 0.5Hz when it's searching for an ANT-FS host and once a host link is established the device sets the Beacon Period to the host's (presumably 4Hz). Is this correct?

If so, does the beacon period revert to 0.5Hz when the Host disconnects or does the period remain at 4Hz?

This matters to me as a power savings.

It is also my understanding that the only downside to having a 0.5Hz beacon period is that it may take a bit longer to find a host. If true, any idea how much longer it will take? Just a figure of merit is all I need, I'm not looking for precision here...

I'm currently using SDK version 10.0.0.0 but will be upgrading to 12.0.0.0 soon. nRF51422 device (Dynastream N5180).

Thanks in advance,
Tom      

Hi TomWS,

Yes, The client transmits at a set channel period until a host link command is received at which point it transmits at the channel period and frequency specified in the command.

Yes, the beacon reverts to the original channel period (see Section 7.3 of the ANT-FS Technical Specification).

A 0.5 Hz beacon period means the beacon is transmitted once every 2 seconds. Depending on the kind of search mechanism used by the Host, it may take more than 30 seconds for the Host to find the link beacon whereas a 4 Hz beacon would take no more than 15 seconds.

Typically, a 4Hz beacon can operate on a coin-cell battery for a year.
     

Excellent! Thanks for the fast and detailed response!

BK - 29 September 2016 11:03 AM

Typically, a 4Hz beacon can operate on a coin-cell battery for a year.

Hmmm, power estimator shows 4Hz TX with no response at average current of 83.3uA with a 2032 coin cell lasting 110 days. What am I missing?

Tom      

My apologies, my estimate was not for all day transmission.      

Ah, ok, thanks for the clarification! I was beginning to think I had totally missed something

In my case, the longer time to find a Host is acceptable if I can do 12/7 beaconing. I'll fiddle with the beacon rate, but knowing that I can was the key thing - thanks again!

Tom