Table 1: Legend of symbols used in the text and their signification.

From: Signal coverage approach to the detection probability of hypothetical extraterrestrial emitters in the Milky Way

ROuter radius of a spherical shell signal
Δ, ΔM, Thickness, maximum thickness, and average thickness of a spherical shell signal
Ω0Solid angle of a conical beam signal
RoObservable radius
RMMaximum possible distance of an emitter from the Earth
tM = (RM + ΔM)/cAge of the oldest detectable signal
NNumber of galactic signals emitted within a time tM from present
Density probability that an emitter is found at
T*Time interval spanned by the age distribution of communication civilizations in the Milky Way.
ϕDetection probability (it is defined as the probability that there is at least one emitter within a distance Ro whose signal intercepts the Earth)
Mean number of detectable emitters