Ultra-Wideband Waveform Tutorial

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Ultra-Wideband Waveform Tutorial
Ultra-Wideband Waveform Tutorial
Svein-Erik Hamran
May 2009
What is UWB?
• Definition
– Fractional Bandwidth: FB > 0.25 or BW > 500MHz
– Where
– Example fL=1GHz and fH=3GHz gives FB = 1
1
Resolution – Bandwidth FB = 20%
Resolution – Bandwidth FB = 100%
2
Range Resolution
Allowable level of a signal dBm
m
Radiation level
3.1
10.6
1.99
Medical systems
Ground penetrating radar
General restriction
Band of
the GPS
0.96
1.61
Frequency GHz
3
UWB waveforms
• UWB signals is very often several GHz wide
• Difficult to collect all the spectrum all the time.
• All UWB waveforms has a way to reduce sampling speed
Impulse Radar
4
Sequential Sampling Receiver
Dual Ramp Timing Circuit
clock
fast
ramp
slow
ramp
comparator
sampling pulse
5
Single Bit Receiver
Block diagram of a noise radar
6
Analog correlation receiver
NOISE
SOURCE
COUPLER
TXantenna
DELAY LINE
RXantenna
MIXER
LOW-PASS
FILTER
RESPONSE
Range response
7
Digital correlation receiver
NOISE
SOURCE
COUPLER
TXantenna
RXantenna
LOW-PASS
FILTER
ADC
ADC
DIGITAL CORRELATION
RESPONSE
Multi vs. One bit ADC
• Sign bit i.e. 1 if s(t)>=0 and -1 if s(t)<0
8
3-reflectors Multi-bit ADC
3-Reflectors
• Multi bit
1-bit
9
3 – Reflectors One – bit ADC
Pulse Train Spectrum
10
Step-frequency radar
frequency
SFCW
B
Δf
time
Step Frequency Waveform
11
FMCW
Transmit
and receive
Local
oscillator
output
Mixer
output
t t
Range
response
Amplitude frequuency frequency frrequency
Chirp radar
Transmit
Echo from 3 targets
time
time
time
f
12

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