EVM的值是反应接收机还是发射机的参数？

Either Tx or Rx, both can use EVM to verify performance.
Tx EVM is defined in Test spec. Rx EVM is not.
However, Rx EVM sometimes is also important, to illustrate the Receiver's capability to demodulate signals.
For exp, Rx EVM can be simply transfer to Noise Figure--this can reflect Rx system noise control capability;
Rx EVM can also illustrate some "non-linear" interference: Pll's phase noise, fix-freq. interference, etc..
A HSDPA system will request very low Rx EVM to get a good throughput.

TX/RX链路都会产生EVM误差的....

应该是TX, 8PSK调制用

一般来说是RX吧。
IQ信号给基带处理器的星座图的一个偏差

其实是相对的，
他的发射，不就是你的接收吗?

就是某个信号的，一般只测发射的

发射的吧