Hello again,
Thank you for your patience.
The reason that you are seeing so many channel collisions has to do with timing. In short, the burst messages received by your base station take more time than is available between the station's master channel transmissions. Here's the math:
The 32Hz channel sends a transmission every 31.25 ms. That is the widest window of opportunity that your device will have to receive a transmission (this is ignoring the back-channel receive window time, mind you).
Burst transfers are sent in multiples of 8 bytes, so your 250 byte transer will occupy 256 bytes worth of airtime. Burst transfers are sent at 20 kbps, which is 2500 bytes/s. This is equivalent to 0.4ms/byte of tranmistted data. Therefore 256 bytes will take 102.4ms total to be received.
This means that you can trust your 32Hz channel to experience channel collisions at a rate of 8Hz, and the collisions will persist for three (sometimes four) message periods. Moreover, since the 32Hz channel period is a multiple of the 8Hz channel, the channel collisions will always occur on top of the same point in your shared channel's polling rotation (i.e three or so temperature sensors will always their updates missed).
I have two suggestions for you:
Suggestion 1: Change the channel period of one of these channels so that they are not multiples of each other. By doing this, the channel collisions will occur at a different point in your shared channel polling rotation every time. This will avoid totally missing all of the updates from a particular set of sensors.
Suggestion 2: Use advanced bursting. Advanced bursting lowers the overhead associated with burst messaging, increasing data throughput to 60kbps (See the ANT Message Protocol and Usage document sections 5.4.4, 9.5.2.25 and 9.5.5.4). This will lower the required receive time for your burst to 34ms, reducing the number of channel collisions by a factor of 3.
Let me know how it goes,
laprairie
