Mantracourt T24 User Manual page 31

Here we can see some visible red traces indicating the minimum signal levels. Around channel 2 there is
something transmitting constantly but the signal is so low that T24 would operate fine anyway. However, channel
12 shows that there is a constant transmission that is above the v3.x radio CCA threshold so those T24 radios
would not function on channel 12. Version 4.0 and above T24 radios would function but communications may be
erratic and certainly the range and coverage would be reduced. It would not be a good idea to use channel 12.
Here we can see a scenario where the entire band noise floor is high. This means that across all channels the
range achievable will be reduced because T24 transmissions from distant modules will be swamped by the
constant signal from the noise floor. For most channels the minimum signal level is below the CCA threshold, so
as long as the T24 signal is strong enough the system will still work. However, note the sloping nature of the red
trace. At around channel 16 the minimum signal level is at the level of the v3.x radio CCA threshold so version 3.x
radios would not be able to pair because channel 16 is used in the pairing negotiation. V4.0 radios would still
operate successfully.
USB 3.0 ports are known to have radio emission problems that can result in exactly the
above scenario. This will always have the effect of reducing the operating range if a USB
base station is used and the antenna is positioned close to the USB 3.0 port. This affects
base station dongles mostly, but can affect any base station placed close to the USB port.
Not all USB 3.0 ports exhibit this problem. Plugging into an adjacent USB 2.0 port may or
may not fix the issue depending on internal PC architecture. Use a USB port away from
USB 3.0 ports or use a short USB extension cable if affected. This affects all 2.4GHz
electronics not just T24.
Mantracourt Electronics Limited
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T24 Telemetry User Manual