ANT Forum

Hi,

I have written a C# program that collects the heart rates of users in a group setting and displays them in real time. The program has been working fine until just recently some new people joined the group/are working out in the same area and they have conflicting HRM device numbers. I am needing a way to distinguish between those HRM devices with the same device numbers that are conflicting. Currently I am getting the device number from the ANT_ChannelID.getDeviceIDfromExt() function.

5.3.4.3 of the ANT Device Profile Heart Rate Monitor states

5.3.4.3 Serial Number Determination
The 16 bit device number allows a unique identification of the device in the RF domain, but cannot uniquely identify all
manufactured heart rate monitors. When used in combination with the Manufacturer ID and the upper 16 bits of the serial
number transmitted in this message, a unique identification of the heart rate monitor can be made.
The 32-bit serial number comprised of the upper serial number (most significant 16 bits) and the device number (least
significant 16 bits) provides more than 4 billion serial numbers for each manufacturer ID. The manufacturer must ensure
that this data is unique for each heart rate monitor produced.
It is important to note that the device ID must never be 0, therefore serial numbers that are integer multiples of 65536
must not be used. See section 4.2.2 for more details.

The manufacturer ID/serial number is sent in data page 2, which is a background data page that is sent atleast once every 64 messages. Is it possible to get the manufacturer ID/serial number or some other unique identifier that I can use with the device number more often than every 64th message? So I can continue to display the heart rates in as real time as possible rather than updating it only every 16 seconds (HRM transmits at about 4Hz)?

Thanks      

Hi,

Newer heart rate straps have been using an extended 20-bit device number by also using the upper nibble of the transmission type byte, so you can check the transmission type to see if it differs on these other HR straps as well.

Also, there are plans on newer straps to rotate page 2 in more often by some manufacturers but I do not believe these are available yet.

If an extended device number is not available, for now you will have to use time estimation for when you do see page 2, to associate that 4 Hz transmission stream with that serial number.      

Thank you for the reply,

I will look into the extended 20-bit device number.

Do you have more information on which manufacturers are planning on rotating page 2 in more often in the near future and when they might be available?

Thanks