Workshops/Workshops/RadarSystems2009/RadarSystems2009/openradar workshop tutorial timing waveforms

Radar Timing and Waveform Tutorial

In this tutorial we will evaluate the ambiguity function for several common waveforms and examine their properties. Finally we will invent a waveform and examine the resulting ambiguity function.

1. Login to your Linux tutorial workstation using the guest account and the provided password.

2. Open a bash shell terminal window by clicking the icon on the tool bar.

3. In the terminal window, change directory to the timing_waveform_tutorial directory.

   • [guest@minos ~]$ cd timing_waveform_tutorial/   
         

4. First evaluate the ambiguity function of a 500 usec uncoded pulse.

   • 
     [guest@minos timing_waveform_tutorial]$ python s500_ambi.py
     generating waveform...
     correlating...
     correlation duration :  41.4949080944
     plotting...
     
         

   1. What is the range resolution implied by this ambiguity function?

   • b. What is the doppler resolution?

     c. Is this a good waveform for measuring the E-region, F-region, or meteor trails?

     d. What is good about using an uncoded pulse?

     e. What is bad about using an uncoded pulse?

5. Next evaluate the ambiguity function of a 520 usec 13 baud barker code.

   • [guest@minos timing_waveform_tutorial]$ python b520_ambi.py
     generating waveform...
     code is  [1, 1, 1, 1, 1, -1, -1, 1, 1, -1, 1, -1, 1]
     correlating...
     correlation duration :  70.6643710136
     plotting...
        

   1. What is the range resolution implied by this ambiguity function?

   • b. What is the doppler resolution?

     c. Is this a good waveform for measuring the E-region, F-region, or meteor trails?

     d. What is good about using a coded pulse?

     e. What is bad about using a coded pulse?

6. Next you will invent several waveforms of different lengths. They will use half the baud length of the above barker code. Produce the best codes you can of length 10, 13, 18, and 24. No barker codes are allowed. Google Scholar is allowed unless you are Finnish or named Phil (if used, you must provide references). Evaluate the waveform ambiguities as follows by substituting your waveform in the command:

   • [guest@minos timing_waveform_tutorial]$ python mycode_ambi.py [1,-1,-1,1,1,1,-1,-1,-1,1,1,1,1,1,-1,-1,1,1,1,1,1,1,1,1,-1,1,1,1]
     generating waveform...
     code is  [ 1 -1 -1  1  1  1 -1 -1 -1  1  1  1  1  1 -1 -1  1  1  1  1  1  1  1  1 -1
       1  1  1]
     correlating...
     correlation duration :  75.5498490334
     plotting...
        

   1. When you get a good code, be sure to save a plots of the resulting ambiguity functions. Try more than one to see how things change.

   • b. What is the range resolution implied by this ambiguity function?

     c. What is the doppler resolution?

     d. What are the sidelobe levels?

     e. Is this a good radar waveform?

     f. How does it compare to the prior barker code?

     g. Discuss ways to improve the performance of such waveforms.

7. Rejoin the other groups. We will now compare the signals invented and discuss them.