When are 2 Out of Pass Band
Signals a Problem?
•
If you know the close-in dynamic range of a radio, at what
signal level will IMD start to be a problem?
•
Assume
S9 = 50
m
V
which is
–73 dBm
•
Assume a typical radio:
u
500 Hz CW filter
u
Noise Floor of -128 dBm
u
Preamp OFF
Dynamic Range
Signal Level Causing IMD = Noise Floor
55 dB
S9
60 dB
S9 + 5 dB
65 dB
S9 + 10 dB
70 dB
S9 + 15 dB
75 dB
S9 + 20 dB
80 dB
S9 + 25 dB
85 dB
S9 + 30 dB
90 dB
S9 + 35 dB
95 dB
S9 + 40 dB