Digital Signal Processing Reference
In-Depth Information
PM/FM Demodulation Scheme 1
HIL99F1.0
1.2
1.E+01
1
1.E+00
0.8
1.E-01
0.6
1.E-02
0.4
1.E-03
0.2
1.E-04
0
1.E-05
-0.2
1.E-06
0
20
40
60
80
100
0
0.2
0.4
0.6
0.8
1
Time / (Sampling Period)
Normalized Carrier Frequency,
F
0.3
1.E+00
0.25
1.E-01
F = 0.25
0.2
1.E-02
F = 0.35
0.15
1.E-03
F = 0.45, 0.55
0.1
1.E-04
0.05
1.E-05
1.E-06
0
0.0001
0.001
0.01
0.1
1
0.1
1
10
100
1000
Modulation Frequency
Modulation Amplitude (degrees)
Notes:
(1)
Phase step response determined at carrier frequency F of 0.5.
(2)
All frequencies and bandwidths normalized with respect to the Nyquist frequency.
ac phase error carried out for modulation amplitude of 30
o
for shown carrier frequency, F.
(3)
Maximum dc phase error found when the phase input is dc and varies from 0
o
to 90
o
for each carrier
frequency shown.
(4)
(5)
Filter length of 99 using
HIL99F1.0
and a delay of L/2 (= 49) for path through LPF in Scheme 1.
2
2
, where noise amplification factor
2
(6)
Output noise power
σ
ϕ
≈
ησ
ε
η
= 1.52, provided input noise power
σ
ε
10 deg
2
(0.175 rad
2
).
≤
(7)
Empirical relation between bandwidth
B
dem
and modulation amplitude
ϕ
o
for carrier frequency
F
= 0.5.
−
0
02
ln
ϕ
−
0
24
B
≈
0
24
ϕ
o
dem
o
