Power spectral density — before despread (at the receiver)
After despread — correlate with the code
wanted signal
jammer
post-despread J/S threshold
Spreading technique
DSSS (chips / bit)
FHSS (hops)
Chips / bit
Jammer J/S
20.0 dB
Processing gain
G
p
—
—
Pre-despread J/S
—
Post-despread J/S
—
(J/S − G
p
)
Spread link
—
Reference narrowband link (
G
p
≈ 0)
—
dies the moment J/S > threshold