Pulses on the wire & what the radar makes of them
transmitted pulse (width c·τ)
echo returning
R
u
— the fold line
drop-line: truth → blip
Waveform (X-band,
λ = 3 cm
)
PRF
10.0 kHz
Pulse width τ
10.0 µs
Target A speed
+50 m/s
Sim speed
40 µs/s
Low 1 kHz
Medium 10 kHz
High 200 kHz
❚❚ Pause
Step 1 PRI
Reset
pulse width pulled down — a transmitter cannot be on longer than its PRI
Drag
A
,
B
or
C
along the wire. Positive speed is
inbound
(closing on the radar).
Pulse-to-pulse phase — the Doppler sampler
gold — the target's actual phase, spinning continuously
navy — what the radar samples, once per echo
Δ
φ
/ pulse
+120°
true +120°
v
true
+50
m/s
v
measured
+50
m/s
measured correctly
±180° per pulse ↔ ±v
u
= λ·PRF/4
ΔR =
cτ
/2
1.5 km
range resolution
R_u = c
/2·PRF
15.0 km
unamb. range
v_u = λ
·PRF/4
75 m/s
unamb. velocity
1st blind speed
150 m/s
λ·PRF/2
Duty cycle
10.0%
τ · PRF