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Measurements >> RF Measurements >> Evaluation of SNDR using EVM
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Message started by Pashtet on Aug 24^th, 2010, 8:01am

Title: Evaluation of SNDR using EVM
Post by Pashtet on Aug 24^th, 2010, 8:01am

Hello friends.

Suppose, I want to measure SNDR of signal in digital modulation system.
As i know this thing is done through EVM measurement.
For example, if i get EVM = 0.1 does this mean that SNDR = 20* log10(1/EVM)= 20 dB - is this value right? Are there any restrictions for evaluation performance through EVM? Would be thankful for any useful links to literature.

Thanks in advance.

Title: Re: Evaluation of SNDR using EVM
Post by RFICDUDE on Aug 24^th, 2010, 6:54pm

In general you are correct to assume the relation

SNDR=20LOG(1/EVM)

Although, this relation maybe too simple depending on the complexity of the equalization system, but in my experience the relation is accurate.

It is also possible to measure SNDR using correlation techniques where you crosscorrelate the SNDR signal with the original signal. This, of course, only works for characterization since in an actual system you don't have access to the original signal.

Title: Re: Evaluation of SNDR using EVM
Post by RFICDUDE on Aug 24^th, 2010, 6:58pm

Oh, I suppose one useful reference (among many) would include.

K. M. Gharaibeh, K. G. Gard, and M. B. Steer, "Accurate Estimation of Digital Communication System Metrics — SNR, EVM and Rho in a Nonlinear Amplifier Environment," 64th ARFTG Microwave Measurements Conference, December 2004, pp. 41-44.

Title: Re: Evaluation of SNDR using EVM
Post by Pashtet on Aug 26^th, 2010, 4:27am

Thanks for your reply!