1
00:00:00,589 --> 00:00:03,428
Hi my name is Rick Gentile on the

2
00:00:03,629 --> 00:00:04,629
product manager for the phased array

3
00:00:04,830 --> 00:00:06,698
system tool box. I want to show you how

4
00:00:06,899 --> 00:00:08,500
easy it is to generate a radar data cube

5
00:00:08,699 --> 00:00:10,269
using MATLAB. In the phased array system

6
00:00:10,468 --> 00:00:12,189
tool box you could find a good

7
00:00:12,388 --> 00:00:13,780
description of the radar data cube and

8
00:00:13,980 --> 00:00:15,460
fundamentals of radar signal processing

9
00:00:15,660 --> 00:00:18,460
by Mark Richards. In this book he

10
00:00:18,660 --> 00:00:20,019
describes the radar data cube it's a

11
00:00:20,219 --> 00:00:21,609
convenient way to represent a collection

12
00:00:21,809 --> 00:00:23,829
of received radar signals built up

13
00:00:24,028 --> 00:00:26,980
sample by sample in space and time once

14
00:00:27,179 --> 00:00:28,690
the receive data is put into this data

15
00:00:28,890 --> 00:00:30,999
cube format various signal processing

16
00:00:31,199 --> 00:00:32,679
Techniques can be used to enhance the

17
00:00:32,880 --> 00:00:35,709
target returns and extract range speed

18
00:00:35,909 --> 00:00:37,469
and bearing information from the data

19
00:00:37,670 --> 00:00:39,909
These techniques include algorithms such

20
00:00:40,109 --> 00:00:42,219
as pulse compression, doppler processing,

21
00:00:42,420 --> 00:00:45,189
and beam forming. So, to build up a radar

22
00:00:45,390 --> 00:00:48,338
data cube will need a few things. We'll

23
00:00:48,539 --> 00:00:49,509
start with a single pulse that's

24
00:00:49,710 --> 00:00:51,939
reflected off the target the received

25
00:00:52,140 --> 00:00:54,489
data is sampled in time the samples can

26
00:00:54,689 --> 00:00:55,989
be used to calculate the distance to the

27
00:00:56,189 --> 00:00:58,419
target these time samples are sometimes

28
00:00:58,619 --> 00:01:00,669
called range bins. They make up the

29
00:01:00,869 --> 00:01:03,279
y-axis of the data cube. this is referred

30
00:01:03,479 --> 00:01:05,138
to as the fast time dimension because

31
00:01:05,338 --> 00:01:06,488
the sampling rate can sometimes be

32
00:01:06,688 --> 00:01:08,168
pretty high from the tens of MHz

33
00:01:08,368 --> 00:01:11,349
to a GHz or higher. A single radar

34
00:01:11,549 --> 00:01:12,700
target reflection will often be

35
00:01:12,900 --> 00:01:14,168
collected at an array of receive

36
00:01:14,368 --> 00:01:16,209
elements, each one of these elements

37
00:01:16,409 --> 00:01:18,488
makes up an individual channel which

38
00:01:18,688 --> 00:01:20,168
makes up the X dimension of the radar

39
00:01:20,368 --> 00:01:23,019
data cube in the figure. Spatially,

40
00:01:23,219 --> 00:01:24,640
sampling the receive signals like this

41
00:01:24,840 --> 00:01:26,769
will allow us to determine the bearing

42
00:01:26,969 --> 00:01:28,899
of the target if we use algorithms like

43
00:01:29,099 --> 00:01:30,488
beam forming and direction of arrival

44
00:01:30,688 --> 00:01:33,640
estimation. You might be transmitting and

45
00:01:33,840 --> 00:01:35,439
receiving multiple pulses in a selected

46
00:01:35,640 --> 00:01:37,689
direction at a rate called the pulse

47
00:01:37,890 --> 00:01:40,329
repetition frequency. The time base for a

48
00:01:40,530 --> 00:01:42,549
collection of pulses is sometimes called

49
00:01:42,750 --> 00:01:45,009
the coherent processing interval this

50
00:01:45,209 --> 00:01:46,869
will be a much slower rate than the

51
00:01:47,069 --> 00:01:48,519
range gate sampling so pulse repetition

52
00:01:48,719 --> 00:01:51,399
frequency of 1 to 10 kilohertz would be

53
00:01:51,599 --> 00:01:54,819
a typical range this is the dimension of

54
00:01:55,019 --> 00:01:56,319
the radar data cube it is sometimes

55
00:01:56,519 --> 00:01:58,539
called a slow time dimension the

56
00:01:58,739 --> 00:01:59,918
information you get from this collection

57
00:02:00,118 --> 00:02:01,509
of data is something you can use to

58
00:02:01,709 --> 00:02:04,090
determine the speed of the target well

59
00:02:04,290 --> 00:02:05,259
let's take a look at how we can do this

60
00:02:05,459 --> 00:02:09,550
in matlab ok we'll see that it's

61
00:02:09,750 --> 00:02:11,110
relatively easy to generate pulse

62
00:02:11,310 --> 00:02:13,700
waveforms reflect the pulses Offit are

63
00:02:13,900 --> 00:02:15,618
and collect the receive signals into the

64
00:02:15,818 --> 00:02:19,310
radar data cube here's the MATLAB code

65
00:02:19,509 --> 00:02:21,050
that we can use to build our own radar

66
00:02:21,250 --> 00:02:23,840
data cube we'll take a look at some

67
00:02:24,039 --> 00:02:25,700
phased array system toolbox functions

68
00:02:25,900 --> 00:02:27,590
and system objects that can be used to

69
00:02:27,789 --> 00:02:30,259
create a target at a 30 kilometer

70
00:02:30,459 --> 00:02:33,819
distance and 150 meter per second speed

71
00:02:34,019 --> 00:02:36,200
now this another phased array system

72
00:02:36,400 --> 00:02:38,539
toolbox object here that we can use to

73
00:02:38,739 --> 00:02:41,300
create an eight element array so our

74
00:02:41,500 --> 00:02:42,709
data cube will have eight receive

75
00:02:42,908 --> 00:02:46,520
channels now here's our waveform which

76
00:02:46,719 --> 00:02:48,530
is a swept FM pulse with a ten percent

77
00:02:48,729 --> 00:02:51,050
duty cycle you can see the sample rate

78
00:02:51,250 --> 00:02:53,420
for this waveform is one mega Hertz and

79
00:02:53,620 --> 00:02:56,868
the PRF is one kilohertz this means

80
00:02:57,068 --> 00:02:58,340
there will be a thousand samples per

81
00:02:58,539 --> 00:03:01,129
radar pulse this will make up the time

82
00:03:01,329 --> 00:03:04,550
dimension of our radar data cube I'll

83
00:03:04,750 --> 00:03:06,649
run this piece of code and you'll see it

84
00:03:06,848 --> 00:03:10,429
takes about 40 lines of code what we've

85
00:03:10,628 --> 00:03:12,709
created are the MATLAB objects which can

86
00:03:12,908 --> 00:03:15,439
be seen in MATLAB workspace window over

87
00:03:15,639 --> 00:03:18,409
here these are the objects we'll use to

88
00:03:18,609 --> 00:03:19,969
simulate and generate our radar data

89
00:03:20,169 --> 00:03:23,060
cube now the actual generation of the

90
00:03:23,259 --> 00:03:24,800
radar data cube only takes about 15

91
00:03:25,000 --> 00:03:27,530
lines of code you can see it in the

92
00:03:27,729 --> 00:03:29,270
simulation loop here that there are the

93
00:03:29,469 --> 00:03:33,289
32 pulses this is the size of the loop

94
00:03:33,489 --> 00:03:36,469
shown right here now this loop generates

95
00:03:36,669 --> 00:03:39,289
the radar pulse and updates the target

96
00:03:39,489 --> 00:03:40,819
position and propagates the pulse we

97
00:03:41,019 --> 00:03:42,920
generated and reflects off the target

98
00:03:43,120 --> 00:03:45,560
and propagates back to the radar now all

99
00:03:45,759 --> 00:03:47,390
of these returns are collected they're

100
00:03:47,590 --> 00:03:49,460
actually collected right here and the

101
00:03:49,659 --> 00:03:51,020
radar data cube can be assembled at this

102
00:03:51,219 --> 00:03:53,719
point when I run this piece of code I

103
00:03:53,919 --> 00:03:57,379
produce my radar data cube we can see

104
00:03:57,579 --> 00:03:58,789
over here that the dimension of the

105
00:03:58,989 --> 00:04:01,849
radar data cube is here and there are

106
00:04:02,049 --> 00:04:04,009
complex IQ samples that are collected at

107
00:04:04,209 --> 00:04:06,590
the array and the dimensions are a

108
00:04:06,789 --> 00:04:08,749
thousand time samples by eight receive

109
00:04:08,949 --> 00:04:12,590
elements by 32 pulses this is a plot of

110
00:04:12,789 --> 00:04:14,659
a signal receive for one data Channel

111
00:04:14,859 --> 00:04:18,199
for the entire 32 pulse duration now you

112
00:04:18,399 --> 00:04:19,579
might think that the first simulation

113
00:04:19,779 --> 00:04:22,579
was a small data cube so let's increase

114
00:04:22,779 --> 00:04:25,218
the complexity a little bit this next

115
00:04:25,418 --> 00:04:27,170
example instead of having one target

116
00:04:27,370 --> 00:04:27,410
we're

117
00:04:27,610 --> 00:04:29,269
I have 20 targets with random positions

118
00:04:29,468 --> 00:04:33,110
in velocity I receive array will be 121

119
00:04:33,310 --> 00:04:34,639
elements mounted on the surface of a

120
00:04:34,839 --> 00:04:37,879
sphere also we've increased our

121
00:04:38,079 --> 00:04:40,100
bandwidth of the waveform from 1

122
00:04:40,300 --> 00:04:42,949
megahertz the 20 megahertz to give us

123
00:04:43,149 --> 00:04:45,439
additional resolution now the

124
00:04:45,639 --> 00:04:46,999
initialization is a few more lines of

125
00:04:47,199 --> 00:04:48,860
code than in our previous example you

126
00:04:49,060 --> 00:04:51,259
can see the array geometry that we have

127
00:04:51,459 --> 00:04:53,838
in this plot here you can also see the

128
00:04:54,038 --> 00:04:55,218
loop to build this data cube is

129
00:04:55,418 --> 00:04:57,588
identical down to the previous example

130
00:04:57,788 --> 00:05:00,170
the only difference is that the values

131
00:05:00,370 --> 00:05:03,050
that we pass in for the RCS and the

132
00:05:03,250 --> 00:05:06,170
positions are vectors instead of just a

133
00:05:06,370 --> 00:05:10,040
single value for a single target well go

134
00:05:10,240 --> 00:05:11,300
ahead and execute this code to generate

135
00:05:11,500 --> 00:05:13,519
our new data cube we can see the

136
00:05:13,718 --> 00:05:16,160
dimensions of the new data cube 20,000

137
00:05:16,360 --> 00:05:19,670
time samples across 121 receive elements

138
00:05:19,870 --> 00:05:22,369
and 32 pulses now the dimensions have

139
00:05:22,569 --> 00:05:24,040
grown but it's still easy to generate

140
00:05:24,240 --> 00:05:26,449
now if you're interested in how we can

141
00:05:26,649 --> 00:05:28,759
process a radar data cube to determine

142
00:05:28,959 --> 00:05:30,499
the range speed and bearing from this

143
00:05:30,699 --> 00:05:33,319
data cube please watch part 2 of this

144
00:05:33,519 --> 00:05:35,149
recording titled processing the radar

145
00:05:35,348 --> 00:05:37,459
data cube you can find this on our

146
00:05:37,658 --> 00:05:39,829
website at the phased array system

147
00:05:40,028 --> 00:05:42,410
toolbox product page thank you very much

148
00:05:42,610 --> 00:05:45,028
for your time

149
00:05:47,079 --> 00:05:52,079
you