[Discuss-gnuradio] how long is the averaging length of the SNR estimator?

[William Cox]

Looking at the documentation for "gr_probe_mpsk_snr_c" (http://gnuradio.org/doc/doxygen/classgr__probe__mpsk__snr__c.html), it says it computes a running average of the signal mean/variance. How long is this running average? Meaning, if my SNR is changing over time, how much will past values affect the current value?

Also, is there any discussion of what the alpha smoothing factor does? In the digital-bert example, it's set to a magic "10/symbol rate" number.

Thanks.

-William