binary_to_ascii.py

# -*- coding: utf-8 -*-
"""
Attempt to read Agilent E5100A network analyzer (10kHz-180 MHz) binary data
file and write the contents into a .csv file. The user should store only
'MAIN' array and 'SUB' array, typically in real and imaginary format but
any format will be read in.

I don't know how to get frequency information from the binary file;
I think we would need to save ALL instead of DATA ONLY

Patrick Pribyl - Sep'16; based on C++ version originally written Feb 2009
Updated 14 Aug 2019 - swjtang
Updated 15 Jan 2021 - format to PEP8
"""

import numpy as np
import scipy.constants as const
import struct
import sys
from glob import glob
from .toolbox import qprint


def unpack_record(fdata, verbose=False) -> (np.array, int):
    """
    worker for read_data()
    Parse a data record from the input data
        Each record is of the form
            unsigned x                 ???
            unsigned short npts        number of doubles in array
            unsigned y;                ???
            double data[npts];         data array
    Returns a numpy array with the data, and the number of bytes of the input
    data that were processed
    """
    pos = 0
    x = struct.unpack('=L', fdata[pos:pos+4])[0]       # L = unsigned long
    pos += 4
    npts = struct.unpack('=H', fdata[pos:pos+2])[0]     # H = unsigned short
    pos += 2
    y = struct.unpack('=L', fdata[pos:pos+4])[0]       # L = unsigned long
    pos += 4
    data = struct.unpack('='+str(npts)+'d', fdata[pos:pos+npts*8])  # d=double
    pos += npts*8
    if verbose:
        print('  x =', x, '   y =', y, 'but their meaning is unknown')
        print('npts=', npts)
        print('data=', data[0:4], '...')
    return np.array(data), pos


def read_data(ifn: str, ch=2) -> (np.array, np.array):
    """ read the 'MAIN' and 'SUB' arrays from the input file named in the
    ifn argument
    """

    with open(ifn, 'rb') as f:
        fdata = f.read()   # haha can't be more than 1.44 MB just read it all

    a = struct.unpack('=d', fdata[0:8])[0]      # d = double precision
    b = struct.unpack('=d', fdata[8:16])[0]

    error_count = 0
    if a != 10000 or b != 180000000:
        print("file format may be incorrect due to unexpected first 16 bytes")
        print("...continuing anyway  (a=", a, " b=", b, ")", sep='')
        error_count = 1

    HEADER_SIZE = 0x126

    """
    The file consists of a header followed by 4 data records in this order:
       - LOGMAG CH1 (1)  - "MAIN_ARRAY"
       - LOGMAG CH2 (3)  - "MAIN_ARRAY"
       - PHASE CH1 (2)   - "SUB_ARRAY"
       - PHASE CH2 (4)   - "SUB_ARRAY"
    All four channels are saved even if they are inactive on the scope.
    """
    pos = HEADER_SIZE
    ch1_logmag, n = unpack_record(fdata[pos:])

    pos += n
    ch2_logmag, n = unpack_record(fdata[pos:])

    pos += n
    ch1_phase, n = unpack_record(fdata[pos:])

    pos += n
    ch2_phase, n = unpack_record(fdata[pos:])

    if ch == 1:
        MAIN_array, SUB_array = ch1_logmag, ch1_phase
    else:
        MAIN_array, SUB_array = ch2_logmag, ch2_phase

    if MAIN_array.size != SUB_array.size:
        print("This is probably a bad file: the data array sizes are \
              unequal:", MAIN_array.size, "!=", SUB_array.size)
        if error_count == 0:
            print("continuing anyway, but saving the smaller number of points")
        else:
            print("(not processed)")
            return np.zeros(1), np.zeros(1)

    return MAIN_array, SUB_array

# * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
# defining function for writing the csv files
# usage: OUTPUT = b2a(file=<filename>, options=options)
# f0/f1 - start/stop sweep frequency on VNA, r - helmholtz coil radius,
# g - amplifier gain


def b2a(file=None, f0=10e3, f1=5e6, r=5.4e-2, g=10, ch=2, output=0, quiet=0):
    Re = np.zeros(1)
    Im = np.zeros(1)

    if file is None:
        print('Usage:')
        print('   python E5100A_Reader.py <sumdumfile>')
        print('')
        print('Needs one or more filenames on the command line,'
              ' (Wildcards are OK)')
        print('Appends ".csv" to the filename and writes each file')
        print('e.g. ')
        print('    python "<filename>" *.dat')
        print('will write a bunch of files ending in .dat.csv')
        print('')
        print('In the agilent E5100 network analyzer setup, save binary data,'
              ' MAIN ARRAY and SUB ARRAY only')
        return(None)
    else:
        ifn = glob(file)[0]

        Re, Im = read_data(ifn, ch=ch)
        ofn = ifn[:-4] + '.csv'
        npts = min(Re.size, Im.size)
        if npts <= 1:
            qprint(quiet, 'skipping file "{0}"'.format(ifn))
            # continue
        qprint(quiet, 'writing file "{0}" with {1} entries'.format(ofn, npts))

        freqarr = np.linspace(f0, f1, num=len(Re), dtype='float')
        warr = 2*np.pi*freqarr

        area = 10**(Re/20) / (32 * (4/5)**1.5) * r / (g*const.mu_0*warr)  # m^2

        if output != 0:
            htext = 'freq [Hz],LOGMAG [dB],PHASE [deg],Area NA [m2]'
            np.savetxt(ofn, np.transpose((freqarr, Re, Im, area)),
                       delimiter=",", header=htext)

        # function returns data
        temp = {
            'freq':   freqarr,
            'logmag': Re,
            'phase':  Im,
            'area':   area
        }

        qprint(quiet, '... done')
        return(temp)