EVM testing of freq hopped radio

Hi,
I am testing a system level zero-IF transceiver which also has frequency hopping. The problem is EVM of the system doesn't change even I decrease the gain of LNA or increase the NF. Do I have to stop the frequency hopping?
Is there any link between EVM and frequecy hopping. If u have any idea or paper related to this please tell me.
The baseband is OFDM based and I have very little idea to generate the single tone or stop freq hopping from baseband.
Help needed
/Hai

Hi,

Basically LNA linearity, Mixer balance, SAW filter amplitude/phase imbalance, and DSP filter would all be influences to RX EVM.

You can try to relate hopped characteristic to those items above.
Also, you can ask Vfone for the help, I think.

yes, the system linearity, LO phase noise and maxer balance all have influences on EVM.

So you can analyze such effects carefully.

Hello;
What is EVM? Can you explain it for me?