scaling.jl

# Compute the scaling factors for each measurement technique to ensure that
# analog signal is 99.9% below -1dBFS. Random gaussian noise is technically
# unbounded, so it's not useful to find a normalization level that will ensure
# we never clip, but we can at least find a reasonable level where any clipping
# should have a minimal impact.

"""
    percentilethresh(x, p)

Find the threshold where `p` percent of `x` will be below it.
"""
function percentilethresh(x, p)
    xs = sort(abs.(x))
    xs[ceil(Int, p/100*length(x))]
end

# expsweep and impulse are naturally limited, so no need to compute a scaling
# factor for them

using MeasureIR

rawsig(g::MeasureIR.GolaySequence) = [g.A; g.B]
rawsig(g::MeasureIR.IRMeasurement) = g.sig

data = Dict()
for f in [expsweep, golay, mls, rpms]
    fname = split(string(f),".")[2]
    m = f(2^24)
    thresh = percentilethresh(resample(rawsig(m), 8//1), 99.99)
    data[f] = thresh
    print(".")
end
println()

ref = db2amp(-1)
println("===================")
println("Impulse Gain: ", ref)
println("ExpSweep Gain: ", ref / data[expsweep])
println("Golay Gain: ", ref / data[golay])
println("MLS Gain: ", ref / data[mls])
println("RPMS Gain: ", ref / data[rpms])
println("===================")