ANT Forum

Just now bringing up a project that will have a single master and a few slaves. I am working on the master side of this and am using ANTWare II to observe the broadcast messages I am sending. This is working but every so many packets, the slave reports a receive error. On the surface, this sounds like the two ends are experiencing some kind of beacon/clock drift and the slave is missing receipt of a packet.

1. What is the expected dropped packet rate for broadcast messages?

2. I have seen mention of a "transmit only master channel". What needs to be specified to open one of these? Would this be more appropriate for a single master, multiple slave topology?

3. What is the max frequency of transmission for reliable broadcast messages? A frequency of 100Hz would be ideal? Is this possible? Reasonable? If not, what is?

Thanks in advance for comments, insights, etc.

--Joe      

Hi Joe,

1. In the average office environment I typically see around 96% reception for a 4 Hz channel, though this can vary drastically depending on the RF environment.

2. This can be set in the channel assignment, and is a different hex value than assigning a bi-directional master channel. I strongly recommend against doing this even if your slave channels never send messages to the master channel as this disables ANT master coexistence.

3. This depends on the device you are using but typically if you were using an older AP2 or C7 module the serial bus would restrict you to ~200 Hz. Actual OTA coexistence typically can sustain up to ~300 Hz of total master channel transmissions before timeslots begin constantly overlapping.

If you are the only master transmitting, and you are not doing bi-directional communication, and you are running an SoC only (N550), then you could easily exceed 500 Hz, but this would require quite a bit of testing.      

Hi Harrison, and thanks very much for your reply.

1. The 96% success rate at 4Hz you mention is very encouraging. Do you have any insights about reliability at a much higher rate, such as 100Hz channel rate?

2. In further reading of the documentation, I realize that the transmit only type link is essentially deprecated and will avoid using it. In addition, we have a need for an extremely rare communication from a slave to the master in this design, as well.

3. We are using an N5 module on the slave end in a custom design and an ANTUSB-M device on the master. Should this combination be able to operate a 100Hz channel with reasonable reliability where the traffic is essentially all master-to-slave?

Thanks very much!
--Joe

     

Hi Joe,

1. I wouldn't expect significant differences until the RF channel saturates with timeslots from other master channels (around ~300 Hz).

3. That should work without any issues.

Cheers