Aerospace and Electronic Systems Magazine May 2017 - 8

Collision Avoidance Radar System for the Bullet Train

Figure 7.

Block diagram of the radar front end.

generator board consist of the reference signal for the demodulation
of the received echoes and a LFMCW signal with a bandwidth B =
50 MHz in the frequency range between 75 and 125 MHz, which
can be used as the transmitting signal. The bandwidth of the signal
used here is the tradeoff between the size of the resolution cell and
the processing ability of the equipment in this system.

THE RADAR ANALOG FRONT END
The radar analog front end is designed to achieve modulation
of the baseband signal to a RF of 17.4 GHz, as well as demodulation of the received RF signal echo for the digital baseband
signal. A single-channel transmitter and a multichannel receiver
composed of eight independent linear channels are integrated
in the radar front end accordingly. The block diagram of modulation and demodulation in the radar front end are shown in
Figure 7.
The reference generator integrated in the front end is the heart
of the CA radar, providing clock signals for other components of
the radar system. The frequency division technique used in the reference generator ensures coherency within a single transmitting
signal pulse, as well as between sequenced signal pulses, enabling
high-resolution Doppler processing for the velocity estimation of a
target. The outputs of the reference generator are three local oscillator (LO) frequencies and four fixed frequency clocks. The LO1
(17.3 GHz) is used in the transmitting channel for modulation of
the transmitting signal, the LO2 (15.75 GHz) and the LO3 (1.4
GHz) are used in the receiving channels for demodulation of the
received echo, the clock of 100 MHz and the clock of 25 MHz are
used in the DDS in the signal generator board, and two clocks of
120 MHz are used to drive the analog-to-digital converters (ADCs)
in the data acquisition board.
8

Figure 8.

Analog front end (on the left) and digital section of the CA radar.

The bandpass IF signal from each receiving channel in the
front end is a LFMCW signal with a bandwidth B = 50 MHz in the
frequency range between 125 and 175 MHz. According the theory
of bandpass sampling [27], the valid sampling rate for the IF signal
with a bandwidth of 50 MHz to avoid aliasing ranges from 116.7
million samples/s to 250 million samples/s. In this article, the IF
signal is directly sampled at 120 million samples/s by 16-bit ADCs
embedded in the data acquisition board, providing about 96 dB
of dynamic range. After processing of the digital downconversion
(DDC) and downsampling (filtering processing is included), the
digital IF signal is converted to a digital baseband signal in the
frequency range of 0-25 MHz at a lower sampling rate of 60 million samples/s. The digital baseband signal is then fed to the signal
processing board for further processing.
Two kinds of hardware platforms are integrated in the digital
section for real-time signal processing: field-programmable gate
array (FPGA) and digital signal processing (DSP) unit. FPGA

IEEE A&E SYSTEMS MAGAZINE

MAY 2017



Table of Contents for the Digital Edition of Aerospace and Electronic Systems Magazine May 2017

No label
Aerospace and Electronic Systems Magazine May 2017 - No label
Aerospace and Electronic Systems Magazine May 2017 - Cover2
Aerospace and Electronic Systems Magazine May 2017 - 1
Aerospace and Electronic Systems Magazine May 2017 - 2
Aerospace and Electronic Systems Magazine May 2017 - 3
Aerospace and Electronic Systems Magazine May 2017 - 4
Aerospace and Electronic Systems Magazine May 2017 - 5
Aerospace and Electronic Systems Magazine May 2017 - 6
Aerospace and Electronic Systems Magazine May 2017 - 7
Aerospace and Electronic Systems Magazine May 2017 - 8
Aerospace and Electronic Systems Magazine May 2017 - 9
Aerospace and Electronic Systems Magazine May 2017 - 10
Aerospace and Electronic Systems Magazine May 2017 - 11
Aerospace and Electronic Systems Magazine May 2017 - 12
Aerospace and Electronic Systems Magazine May 2017 - 13
Aerospace and Electronic Systems Magazine May 2017 - 14
Aerospace and Electronic Systems Magazine May 2017 - 15
Aerospace and Electronic Systems Magazine May 2017 - 16
Aerospace and Electronic Systems Magazine May 2017 - 17
Aerospace and Electronic Systems Magazine May 2017 - 18
Aerospace and Electronic Systems Magazine May 2017 - 19
Aerospace and Electronic Systems Magazine May 2017 - 20
Aerospace and Electronic Systems Magazine May 2017 - 21
Aerospace and Electronic Systems Magazine May 2017 - 22
Aerospace and Electronic Systems Magazine May 2017 - 23
Aerospace and Electronic Systems Magazine May 2017 - 24
Aerospace and Electronic Systems Magazine May 2017 - 25
Aerospace and Electronic Systems Magazine May 2017 - 26
Aerospace and Electronic Systems Magazine May 2017 - 27
Aerospace and Electronic Systems Magazine May 2017 - 28
Aerospace and Electronic Systems Magazine May 2017 - 29
Aerospace and Electronic Systems Magazine May 2017 - 30
Aerospace and Electronic Systems Magazine May 2017 - 31
Aerospace and Electronic Systems Magazine May 2017 - 32
Aerospace and Electronic Systems Magazine May 2017 - 33
Aerospace and Electronic Systems Magazine May 2017 - 34
Aerospace and Electronic Systems Magazine May 2017 - 35
Aerospace and Electronic Systems Magazine May 2017 - 36
Aerospace and Electronic Systems Magazine May 2017 - 37
Aerospace and Electronic Systems Magazine May 2017 - 38
Aerospace and Electronic Systems Magazine May 2017 - 39
Aerospace and Electronic Systems Magazine May 2017 - 40
Aerospace and Electronic Systems Magazine May 2017 - 41
Aerospace and Electronic Systems Magazine May 2017 - 42
Aerospace and Electronic Systems Magazine May 2017 - 43
Aerospace and Electronic Systems Magazine May 2017 - 44
Aerospace and Electronic Systems Magazine May 2017 - 45
Aerospace and Electronic Systems Magazine May 2017 - 46
Aerospace and Electronic Systems Magazine May 2017 - 47
Aerospace and Electronic Systems Magazine May 2017 - 48
Aerospace and Electronic Systems Magazine May 2017 - 49
Aerospace and Electronic Systems Magazine May 2017 - 50
Aerospace and Electronic Systems Magazine May 2017 - 51
Aerospace and Electronic Systems Magazine May 2017 - 52
Aerospace and Electronic Systems Magazine May 2017 - 53
Aerospace and Electronic Systems Magazine May 2017 - 54
Aerospace and Electronic Systems Magazine May 2017 - 55
Aerospace and Electronic Systems Magazine May 2017 - 56
Aerospace and Electronic Systems Magazine May 2017 - 57
Aerospace and Electronic Systems Magazine May 2017 - 58
Aerospace and Electronic Systems Magazine May 2017 - 59
Aerospace and Electronic Systems Magazine May 2017 - 60
Aerospace and Electronic Systems Magazine May 2017 - 61
Aerospace and Electronic Systems Magazine May 2017 - 62
Aerospace and Electronic Systems Magazine May 2017 - 63
Aerospace and Electronic Systems Magazine May 2017 - 64
Aerospace and Electronic Systems Magazine May 2017 - Cover3
Aerospace and Electronic Systems Magazine May 2017 - Cover4
http://www.brightcopy.net/allen/aesm/34-2s
http://www.brightcopy.net/allen/aesm/34-2
http://www.brightcopy.net/allen/aesm/34-1
http://www.brightcopy.net/allen/aesm/33-12
http://www.brightcopy.net/allen/aesm/33-11
http://www.brightcopy.net/allen/aesm/33-10
http://www.brightcopy.net/allen/aesm/33-09
http://www.brightcopy.net/allen/aesm/33-8
http://www.brightcopy.net/allen/aesm/33-7
http://www.brightcopy.net/allen/aesm/33-5
http://www.brightcopy.net/allen/aesm/33-4
http://www.brightcopy.net/allen/aesm/33-3
http://www.brightcopy.net/allen/aesm/33-2
http://www.brightcopy.net/allen/aesm/33-1
http://www.brightcopy.net/allen/aesm/32-10
http://www.brightcopy.net/allen/aesm/32-12
http://www.brightcopy.net/allen/aesm/32-9
http://www.brightcopy.net/allen/aesm/32-11
http://www.brightcopy.net/allen/aesm/32-8
http://www.brightcopy.net/allen/aesm/32-7s
http://www.brightcopy.net/allen/aesm/32-7
http://www.brightcopy.net/allen/aesm/32-6
http://www.brightcopy.net/allen/aesm/32-5
http://www.brightcopy.net/allen/aesm/32-4
http://www.brightcopy.net/allen/aesm/32-3
http://www.brightcopy.net/allen/aesm/32-2
http://www.brightcopy.net/allen/aesm/32-1
http://www.brightcopy.net/allen/aesm/31-12
http://www.brightcopy.net/allen/aesm/31-11s
http://www.brightcopy.net/allen/aesm/31-11
http://www.brightcopy.net/allen/aesm/31-10
http://www.brightcopy.net/allen/aesm/31-9
http://www.brightcopy.net/allen/aesm/31-8
http://www.brightcopy.net/allen/aesm/31-7
https://www.nxtbookmedia.com