I read the document about TPM function, I'm not very clear about the variable gain block ( in the read area).
I guss it is a digital VGA? Is it the Programmable TX FIR ? How can we set the value of it?
Hi. I'd like to get some clarification on the TPM. On the diagram above TPM looks like a closed loop system, able to keep the power at the target level without any involvement from the processor, after all configuration, of course. However, I haven't been able to figure out how to actually make it work as an autonomous system on the ZC702/FMCOMMS3 platform. I've read the user and register guide many times now without help. Is there an additional application note, or can someone say that it is not an autonomous system. Also, what is the "LO common mode" setting on the "TX Monitor" tab of the IIO Scope? Thanks.
It is a high level representation of digital gain control available. Please see the documentation on more details about Tx digital path gain adjustment range.
TPM is for Tx output power monitoring and you will get only RSSI value from this. VGA is not adjusted automatically with RSSI. Baseband has to implement the close loop function. So TPM is not a closed loop system.
Also TPM works only for TDD system where Rx path is utilized for power measurement.
In FMCOMMS3 there is provision provided (connector not mounted) for Tx monitor input, J101 and J102 .
As shown in figure above the power amplifier and coupler are not part of FMCOMMS3 and you need to connect that externally for testing.
Moving to Linux SW Subspace for details on "LO common mode" setting on the "TX Monitor" tab of the IIO Scope?
These settings set the common mode of the Tx monitor LO (REG 0x70 & 0x71). However according to the latest reference manual these fields must be set with it's default value of 48, so please don't change them.
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