An implantable cardiac rhythm management device is configured to estimating the
noise level and noise floor in a sensing channel by measuring the magnitude of
signal in the sensing channel when noise is determined to be present or absent,
respectively. The presence or absence of noise may be determined by computing the
density of local peaks or inflection points in an electrogram waveform. The computed
local peak density is then used to set or clear a noise flag, which signifies whether
noise is present or not. A noise statistic computed from samples of the electrogram
signal obtained through a sensing channel may then be used to estimate a noise
level or a noise floor.
