ANT Forum

What are you using to receive / parse the ANT+ messages? If your receiver application only works on the Basic Power Only message (as defined in the spec 0x10) then that is only sent every 1second. If you want higher frequency then the receiver will have to handle the specific power messages (0x11, 0x12, 0x20).

What library are you using on the receiving side?

I'm interested in speaking more with you about your project. I'm working alongside a UK track team to do real time cycling aerodynamic analysis in the velodrome…maybe we can help each other?      

You can not adjust the rate the sensor sends the data at. Some sensors will send data updates more often than others. Quite a lot of them have the update rate tied to the cadence so you only get a new update for one complete pedal revolution. There has been on and off talk about a high speed mode being added to the spec but there is nothing yet. There are some manufacturers with custom formats that may give you higher data rate. You may need to switch to BTLE for some of these but the first thing would be to talk to the specific manufacturer of the power meter your interested in.      

Daff23 - 30 May 2018 06:23 AM

Hi all,

I am currently working on my master thesis in cycling aerodynamics. For our test we would like to ramp up the read out frequency of the Powermeter. (Currently 1Hz).

I have tried playing around with SimulANT+ and managed to write out the data from my powermeter when I cycle on an indoor trainer. However the timestamps are roughly 1 second apart.

In the ANT Messages I see a much higher communication frequency between the powermeter and the receiver at around 5Hz. Is there any way to extract the power data in that sampling frequency?

Any help is welcomed!

Cheers,

Max

I should also say that the FIT files I have looked at always have 1 second resolution, even if the PM is at 4Hz. The receiver must be doing some averaging/rollup of data into a time window. If _you_ write your own receiver you don't have to do that.

Time, ordering events, is a big issue in ANT+ in my opinion. Nowhere is order and simultaneity covered in the docs. A massive oversight for a distributed system, eh? What causes speed and power data from different physical sensors, in different physical locations, to be declared simultaneous and lumped into a single reading?

My rants aside, your power meter _is_ sending at a rate greater than 1Hz, and your data output, if from a FIT file, is made up for that data, but timeboxed/averaged. By what scheme the averaging occurs is the (dirty?) secret of the receiver implementor, and since they're _all_ closed source, you'll never know.