TX Channel Monitoring is done by looping back the transmit signal to an FB channel, via an internal loopback mechanism. Start and Stop Frequency must be selected such that:

1. The monitoring band must be at least 100MHz away from FB channel’s Nyquist band edge.
2. The band you monitor is not supposed to transmit any signal or contain any other spur and must be outside theTX Signal band While selecting a TX band to monitor, do make sure that the band does not contain aliased copies of the TX DAC images that occur when the TX signal is observed via the FB ADC.
3. The monitoring band must be within the same Nyquist in which you transmit.

Here, the Nyquist frequency must be determined according to sampling rate of FB ADCs since the TX output is being monitored using FB channels. Any effect of aliasing must also be considered while selecting the band.

For example, suppose you have your TX NCO at 9250MHz, and interface rate is 200MHz, then you can choose your start Frequency either 9050MHz or 9450MHz whichever satisfies the above conditions. Stop frequency must be 100MHz away from start Frequency to make sure that the monitoring bandwidth is 100MHz. To set the threshold, use the CAPI readTxSnr. TI recommends that threshold must be set 5dB higher than the reported SNR. Refer to the example 3.3 above. Perform the sequence for all the TX Channels.