ANT Forum

Hi.
Using simulant I mainly seem to get 2Hz, not 4Hz frequency for the Wheel Torque power meter profile.
The specs/docs say the channel period is 8192, and the simulant is set up at 8192, yet in general I get messages every ~500ms.

Here is an histogram of the RxTimestamp differences for a sample of data received from simulant.
https://www.dropbox.com/s/dk00c7dakbr1b4t/powertap.png?dl=0

Simulating a CTF power meter, and speed power meter (links below), you'll see the expected 4Hz.
https://www.dropbox.com/s/4i4pubrk7azcxz3/ctf.png?dl=0
https://www.dropbox.com/s/qfjq1osti72xrps/speed.png?dl=0

Is this expected?

Thanks in advance

Russell      

Russell Brown,

The channel frequency of the Bike Power Meter is ~4Hz (There are a few exceptions where the frequency would be ~8Hz).

Would you be able to detail your setup to get these results?

Using the most recent version of SimulANT+ and a simulated Bike Power Display/Sensor(Wheel Torque) I saw a transmission of 4Hz.

N      

Thanks for the reply. As the histo shows, I sometimes see 4Hz, but not always. I wonder if this is background pages, and the power only message?

The CTF simulant profile I get 4Hz (and it doesn't have the extra pages and power only messages)

I have an added complexity/indirection in that I am using a WASP-N ANT->WiFi bridge to relay the messages, so there is every chance that that is where the problem lies.

Which PMs broadcast at 8Hz, out of interest?      

Russel,

Perhaps there is some form of filtering happening between data pages. I would suggest using the SimulANT+ Bike Power simulator and connecting it to you device. There is no filtering out of data pages once connected and you will be able to view all received and transmitted data pages using the ANT Messages tab of the simulator.

The profile supports 8Hz transmission in order to maintain backwards compatibility with older products.

N


     

Thanks.
If the SimulANT+ Bike Power (Wheel Torque) sends a message every 250ms, it stands to reason that the actual wheel torque data page 0x11 is sent less frequently than 250ms, right? Since the profile also sends a power only message every second, and also some background pages.

Does that make sense? That histogram is derived from a log of 0x11 messages only.      

Yes. You are correct. The profile document specifies a transmission of 4Hz, but these messages are anything from main pages, to background pages to common pages. However the transmission pattern must also conform to the profile document specifications.

N