genSignal <- function(NcivsInGal     = 1e6,
                      EmitStartRange = c(-5e9, 5e9),
                      DistRange      = c(300,  1e5),
                      DurRange       = c(1000, 1e5)){

	signals = data.frame(EmitStartYBP = runif(nCivs, EmitStartRange[1], EmitStartRange[2]),
	                     Distance     = runif(nCivs, DistRange[1],      DistRange[2]),
	                     Duration     = runif(nCivs, DurRange[1],       DurRange[2]))

	signals$EmitEndYBP     = with(signals, EmitStartYBP + Duration)
	signals$DetectStartYBP = with(signals, EmitStartYBP + Distance)
	signals$DetectEndYBP   = with(signals, EmitEndYBP   + Distance)

	signals$Detectable = with(signals, DetectStartYBP <= 0 & DetectEndYBP >= 0)
	return(signals)
}

nGalaxies     = 1000
propSignalHit = replicate(nGalaxies, mean(genSignal()$Detectable))

hist(propSignalHit, col = "Blue", breaks = 10, freq = T,
     xlab = "Proportion of Signals Detectable",
     main = paste("Mean =", mean(propSignalHit)))