Echopype Error - Simrad EK80 data: ValueError: zero-size array to reduction operation maximum which has no identity

Question

I am currently trying to get sv values from Simrad EK80 echosounder. I converted the .raw file to .nc (netCDF4) files, using Echopype library (Python). I am now moving on the second step, where I am processing the converted file and calibrate to get sv values. However, if I run the script provided in echopype instruction, I run into the error:

ValueError: zero-size array to reduction operation maximum which has no identity

Does anyone know how to proceed to fix it?

Instruction: https://echopype.readthedocs.io/en/stable/data-proc-func.html

The code I run:

nc_path = r"C:\Users\Runner\Desktop\Echopype\unpacked_files\20220923--D20220923-T082637.nc"  # path to a converted nc file

echodata = ep.open_converted(nc_path)  # create an EchoData object

ds_Sv = ep.calibrate.compute_Sv(echodata, waveform_mode="CW", encode_mode="complex")

The error I get:

---

ValueError                                Traceback (most recent call last)
Cell In[16], line 5
      2 echodata = ep.open_converted(nc_path)  # create an EchoData object
      4 # For EK80 data, you need to specify waveform_mode and encode_mode
----> 5 ds_Sv = ep.calibrate.compute_Sv(echodata, waveform_mode="CW", encode_mode="complex")

File ~\anaconda3\envs\Echopype\lib\site-packages\echopype\calibrate\api.py:206, in compute_Sv(echodata, **kwargs)
    120 def compute_Sv(echodata: EchoData, **kwargs) -> xr.Dataset:
    121     """
    122     Compute volume backscattering strength (Sv) from raw data.
    123 
   (...)
    204     it must be set using `EchoData.update_platform()`.
    205     """
--> 206     return _compute_cal(cal_type="Sv", echodata=echodata, **kwargs)

File ~\anaconda3\envs\Echopype\lib\site-packages\echopype\calibrate\api.py:60, in _compute_cal(cal_type, echodata, env_params, cal_params, ecs_file, waveform_mode, encode_mode)
     58 # Perform calibration
     59 if cal_type == "Sv":
---> 60     cal_ds = cal_obj.compute_Sv()
     61 elif cal_type == "TS":
     62     cal_ds = cal_obj.compute_TS()

File ~\anaconda3\envs\Echopype\lib\site-packages\echopype\calibrate\calibrate_ek.py:628, in CalibrateEK80.compute_Sv(self)
    619 def compute_Sv(self):
    620     """Compute volume backscattering strength (Sv).
    621 
    622     Returns
   (...)
    626         and the corresponding range (``echo_range``) in units meter.
    627     """
--> 628     return self._compute_cal(cal_type="Sv")

File ~\anaconda3\envs\Echopype\lib\site-packages\echopype\calibrate\calibrate_ek.py:612, in CalibrateEK80._compute_cal(self, cal_type)
    606 flag_complex = (
    607     True if self.waveform_mode == "BB" or self.encode_mode == "complex" else False
    608 )
    610 if flag_complex:
    611     # Complex samples can be BB or CW
--> 612     ds_cal = self._cal_complex_samples(cal_type=cal_type)
    613 else:
    614     # Power samples only make sense for CW mode data
    615     ds_cal = self._cal_power_samples(cal_type=cal_type)

File ~\anaconda3\envs\Echopype\lib\site-packages\echopype\calibrate\calibrate_ek.py:501, in CalibrateEK80._cal_complex_samples(self, cal_type)
    498 fs = self.cal_params["receiver_sampling_frequency"]
    500 # Switch to use Andersen implementation for transmit chirp starting v0.6.4
--> 501 tx, tx_time = get_transmit_signal(beam, tx_coeff, self.waveform_mode, fs)
    503 # Params to clarity in use below
    504 z_er = self.cal_params["impedance_transceiver"]

File ~\anaconda3\envs\Echopype\lib\site-packages\echopype\calibrate\ek80_complex.py:248, in get_transmit_signal(beam, coeff, waveform_mode, fs)
    246 fs_chan = fs.sel(channel=ch).data if isinstance(fs, xr.DataArray) else fs
    247 tx_params["fs"] = fs_chan
--> 248 y_ch, _ = tapered_chirp(**tx_params)
    250 # Filter and decimate chirp template
    251 y_ch, y_tmp_time = filter_decimate_chirp(coeff_ch=coeff[ch], y_ch=y_ch, fs=fs_chan)

File ~\anaconda3\envs\Echopype\lib\site-packages\echopype\calibrate\ek80_complex.py:45, in tapered_chirp(fs, transmit_duration_nominal, slope, transmit_frequency_start, transmit_frequency_stop)
     42 y[i0:i1] = y[i0:i1] * w1
     43 y[i2:i3] = y[i2:i3] * w2
---> 45 return y / np.max(y), t

File ~\anaconda3\envs\Echopype\lib\site-packages\numpy\core\fromnumeric.py:2810, in max(a, axis, out, keepdims, initial, where)
   2692 @array_function_dispatch(_max_dispatcher)
   2693 @set_module('numpy')
   2694 def max(a, axis=None, out=None, keepdims=np._NoValue, initial=np._NoValue,
   2695          where=np._NoValue):
   2696     """
   2697     Return the maximum of an array or maximum along an axis.
   2698 
   (...)
   2808     5
   2809     """
-> 2810     return _wrapreduction(a, np.maximum, 'max', axis, None, out,
   2811                           keepdims=keepdims, initial=initial, where=where)

File ~\anaconda3\envs\Echopype\lib\site-packages\numpy\core\fromnumeric.py:88, in _wrapreduction(obj, ufunc, method, axis, dtype, out, **kwargs)
     85         else:
     86             return reduction(axis=axis, out=out, **passkwargs)
---> 88 return ufunc.reduce(obj, axis, dtype, out, **passkwargs)

ValueError: zero-size array to reduction operation maximum which has no identity