#excitation_file with a file MATLAB to generate a sfcw signal

[Andrea]

Good morning I have some questions. Can anyone help me please?

I want to create a simulation for a Stepped Frequency Continuous Wave radar.

 I generate my signal in MATLAB and i want import it in GprMax to simulate it.

Matlab parameter:

Stepped Frequency Continuous Wave Signal GENERATION

PARAMETER:

Amplitude= 1.000000 [V]

N= 51

Bw= 5e+08 [Hz]

Dwell Time= 8.33333e-11[s]

PRI=4.25e-09 [s]

Frequency Step= 10.000000 [MHz]

Range Resolution= 0.094868 [m]

Unambiguous Range= 4.838285[m]

this code generate a txt file named my_wave.txt :

time my_pulse

0 1 

8.33333e-13 0.992115 

1.66667e-12 0.968583 

2.5e-12 0.929776 

3.33333e-12 0.876307 

4.16667e-12 0.809017 

5e-12 0.728969 

5.83333e-12 0.637424 

6.66667e-12 0.535827 

7.5e-12 0.425779 

.. .. ..

GprMax code

#title: scenario_0_cubo_cilindro_al_centro

#domain: 2.0 1.5 0.002

#dx_dy_dz: 0.002 0.002 0.002

#time_window: 8.5e-9

#material: 10 0 1 0 ground

#excitation_file: my_wave.txt

#hertzian_dipole: z 1.0 1.0 0.0 my_pulse

#rx: 1 1.01 0.0

#box: 0 0 0 2.0 1.0 0.002 ground

#cylinder: 1 0.5 0.0 1.0 0.5 0.02 0.1 pec

#geometry_view: 0 0 0 2.0 1.5 0.002 0.002 0.002 0.002 scenario_0_cubo_cilindro_al_centro n

#snapshot: 0 0 0 2.0 1.5 0.002 0.002 0.002 0.002 8.5e-9 snap1

I'm sorry but I can't understand where I'm wrong

The cmd return:

Model title: scenario_0_cubo_cilindro_al_centro

Number of CPU (OpenMP) threads: 4

Spatial discretisation: 0.002 x 0.002 x 0.002m

Domain size: 2 x 1.5 x 0.002m (1000 x 750 x 1 = 750000 cells)

Mode: 2D TMz

Time step (at CFL limit): 4.71731e-12 secs

Time window: 8.5e-09 secs (1803 iterations)

Excitation file: C:\Users\andre\Desktop\gprMax\ESEMPI_PROVA\scenario_0_sfera\my_wave.txt

User waveform my_pulse created using user-defined time array and, if required, interpolation parameters (kind: linear, fill value: nan).

Traceback (most recent call last):

  File "C:\Users\andre\Miniconda3\envs\gprMax\lib\runpy.py", line 193, in _run_module_as_main

    return _run_code(code, main_globals, None,

  File "C:\Users\andre\Miniconda3\envs\gprMax\lib\runpy.py", line 86, in _run_code

    exec(code, run_globals)

  File "C:\Users\andre\Desktop\gprMax\gprMax\__main__.py", line 6, in <module>

    gprMax.gprMax.main()

  File "C:\Users\andre\Desktop\gprMax\gprMax\gprMax.py", line 66, in main

    run_main(args)

  File "C:\Users\andre\Desktop\gprMax\gprMax\gprMax.py", line 188, in run_main

    run_std_sim(args, inputfile, usernamespace)

  File "C:\Users\andre\Desktop\gprMax\gprMax\gprMax.py", line 229, in run_std_sim

    run_model(args, currentmodelrun, modelend - 1, numbermodelruns, inputfile, modelusernamespace)

  File "C:\Users\andre\Desktop\gprMax\gprMax\model_build_run.py", line 166, in run_model

    process_multicmds(multicmds, G)

  File "C:\Users\andre\Desktop\gprMax\gprMax\input_cmds_multiuse.py", line 230, in process_multicmds

    h.calculate_waveform_values(G)

  File "C:\Users\andre\Desktop\gprMax\gprMax\sources.py", line 67, in calculate_waveform_values

    self.waveformvaluesJ[iteration] = waveform.calculate_value(time + 0.5 * G.dt, G.dt)

  File "C:\Users\andre\Desktop\gprMax\gprMax\waveforms.py", line 118, in calculate_value

    ampvalue = self.userfunc(time)

  File "C:\Users\andre\Miniconda3\envs\gprMax\lib\site-packages\scipy\interpolate\polyint.py", line 79, in __call__

    y = self._evaluate(x)

  File "C:\Users\andre\Miniconda3\envs\gprMax\lib\site-packages\scipy\interpolate\interpolate.py", line 663, in _evaluate

    below_bounds, above_bounds = self._check_bounds(x_new)

  File "C:\Users\andre\Miniconda3\envs\gprMax\lib\site-packages\scipy\interpolate\interpolate.py", line 695, in _check_bounds

    raise ValueError("A value in x_new is above the interpolation "

ValueError: A value in x_new is above the interpolation range.

Can anyone help me please?

[Craig Warren]

Dear Andrea,

A quick Google will give you suggestions - https://stackoverflow.com/questions/45429831/valueerror-a-value-in-x-new-is-above-the-interpolation-range-what-other-re

Try using extrapolate with your excitation file command - http://docs.gprmax.com/en/latest/input.html#excitation-file

https://docs.scipy.org/doc/scipy/reference/generated/scipy.interpolate.interp1d.html

Kind regards,

Craig

[Andrea]

thank you very much. I think I understand the mistake. I generate my wave for 4.25e-09 (PRI) second. while I was setting the #time_window: 8.5e-9 (2*PRI), if I set #time_window: 4.25e-09, it works.

So in order not to have the error and to have the time to receive the signal I increased the time up to 8.5e-9 and added 0 as an amplitude value after the time 4.25e-09.

ex:

time my_pulse

0 1

5e-13 0.998027

1e-12 0.992115

1.5e-12 0.982287

2e-12 0.968583

2.5e-12 0.951057

3e-12 0.929776

3.5e-12 0.904827

4e-12 0.876307

4.5e-12 0.844328

5e-12 0.809017

5.5e-12 0.770513

6e-12 0.728969

6.5e-12 0.684547

7e-12 0.637424

7.5e-12 0.587785

....

..

..

2.547e-09 -0.45399

2.5475e-09 -0.382683

2.548e-09 -0.309017

2.5485e-09 -0.233445

2.549e-09 -0.156434

2.5495e-09 -0.0784591

2.55e-09 0

2.5505e-09 0

2.551e-09 0

2.5515e-09 0

...

..

..

.