FMCW Software

1  Basic radar parameters

Parameter Value Unit Comment
C 3*108 m/s Speed of light
sweep_time 0.0005 s Sweep time
Sweep Frequency 2~4 or 5.2~8.2 GHz  
B 2 or 3 GHz Bandwidth
S     S = B / sweep_time
IF 1 MHz adc sample,IF frequency
maximum range   m IF / 2 * c / (2 * S), according to the Nyquist theorem,so IF / 2
if_offset   KHz Zero point estimation, due to the influence of signal cable length

2  Operations before power-on

  • The transmitter antenna and receiver antenna are connected to the corresponding ports of the device.
  • The transmitter must not be empty before powered on.
  • Check whether the control bus is connected.
  • Check whether the synchronization signal cable is connected.
  • Check whether the IF signal line is connected.
  • Check whether the VGA voltage control is connected.
  • Power on FPGA(must be power on before radar, because the output VGA voltage is unstable when it is just powered on).
  • Power on Radar.
  • Use the Ethernet cables to connect FPGA with computer.

3  Packet Parsing

Each frame contains flag、tx no、rx no、frame no adc data.

No field data type packet size description
1 packet flag   12 The flag of each packet
2 timestamp unsigned long long 8 The timestamp,if you parse packet from a file,otherwise,the field is None
3 tx unsigned short 2 The transmitter antenna No
4 rx unsigned short 2 The receiver antenna No
5 frame no unsigned long 4 The frame No
6 adc data unsigned char 1 adc data

4  Process Parameters

Parameter Value Unit Comment
num_tx     the number of tx
num_rx     the number of rx
loop_size     data size after traversing each antenna
num_loop_per_frame     the number of loops each frame
frame_size     the data length of each processing window
num_range_nfft 512   the number of points of range fft
num_doppler_nfft 64   the number of points of doppler fft
num_angle_nfft 180   the number of points of angle fft

5  About the repository

5.1 Install Dependencies

   pip install -r requirements.txt -i https://pypi.mirrors.ustc.edu.cn/simple/

5.2 Changing the IP Address

  • The FPGA default IP address is "192.168.0.2",default port is 5000;By default ,it send to the IP address "192.168.0.3" and port 6000.
  • So modify the localhost IP address to "192.168.0.3".

5.3 Select the antenna number you want to use by modifying txs list and rxs list

   local_udp_ip = "192.168.0.3"
   local_udp_port = 6000
   fpga_udp_ip = "192.168.0.2"
   fpga_udp_port = 5000
   
   # FPGA use antenna no
   txs = [3,4]
   rxs = [1,2,3,4,5,6,7,8,9,10]
   
   r = Receive(local_udp_ip,local_udp_port,fpga_udp_ip,fpga_udp_port)
   msg,result = r.setting(txs,rxs)

5.4 Plot data real time

   python plot_data_real_time.py

5.5 Save raw data to file,

  • You can run the following script if you want to save the data locally,and the file will be saved in ‘./data/'.

     python receiving_data_and_save.py

  • This script saves the local time for easy time synchronization.

5.6 Plot data from file

   python plot_data_from_file.py

6  Algorithm processing flow

  1. Range FFT
  2. Remove DC
  3. Doppler FFT
  4. Angle FFT
  5. Find the target
  6. Point cloud
  7. Point cloud clustering

7  FQA

  1. How does the antenna switch work?

    If the working tx antennas is [1,2],rx antennas is [1,2,3,4,5], and the switching order is:tx1,rx1,rx2,rx3,rx4,rx5,tx2,rx1,rx2,rx3,rx4,rx5.