gitting project in git

python/read_data_file.py

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+import ctypes
+import os.path
+import time
+import numpy as np
+from matplotlib import pyplot as plt
+import socket
+
+import data_structures
+import radar_manager
+from data_recorder import DataRecorder
+
+
+def db20(x):
+    return 20*np.log10(np.abs(x))
+
+
+def db20n(x):
+    x = db20(x)
+    x = x - np.max(x)
+    return x
+
+
+def main():
+    print('Hello')
+
+    clk = 187.5e6
+
+    # Parse Data
+    headers = []
+    offset = 0
+
+    file = 'test0.bin'
+    fid = open(file, 'rb')
+
+    # Find header, recording buffer could have wrapped depending on data rate and how long we ran for
+    hdr_sync = False
+    while not hdr_sync:
+        # data = recorder.buffer[offset:offset + 4]
+        data = fid.read(4)
+        sync_word = np.frombuffer(data, dtype=np.uint32)[0]
+        if sync_word == 0xAABBCCDD:
+            hdr_sync = True
+            print('Header found at offset', offset)
+            fid.seek(-4, 1)
+
+    # Get the first header
+    header = fid.read(ctypes.sizeof(data_structures.CpiHeader))
+    header = data_structures.CpiHeader.from_buffer_copy(header)
+    fid.seek(-ctypes.sizeof(data_structures.CpiHeader), 1)
+
+
+    # CPI Parameters (timing values are in clk ticks)
+    num_pulses = header.num_pulses
+    num_samples = header.num_samples
+    pri = header.pri
+    inter_cpi = header.inter_cpi
+    data_size = num_pulses * num_samples * 4
+
+    file_size = os.path.getsize(file)
+    expected_num_cpis = int(file_size / (ctypes.sizeof(data_structures.CpiHeader) + data_size))
+    print('Expected CPIS:', expected_num_cpis)
+
+
+    for i in range(expected_num_cpis):
+        # Get Header
+        data = fid.read(ctypes.sizeof(data_structures.CpiHeader))
+        headers.append(data_structures.CpiHeader.from_buffer_copy(data))
+
+        # Get CPI
+        data = fid.read(data_size)
+
+    # Check some header fields
+    cpi_times = np.array([x.system_time for x in headers]) / 187.5e6
+    pps_frac = np.array([x.pps_frac_sec for x in headers]) / 187.5e6
+    pps_sec = np.array([x.pps_sec for x in headers])
+    utc_time = pps_sec + pps_frac
+    print(pri, inter_cpi, num_pulses * pri + inter_cpi)
+    print(cpi_times - cpi_times[0])
+    print(pps_frac)
+    print(pps_sec - pps_sec[0])
+
+    # Plot last CPI
+    data2 = np.frombuffer(data, dtype=np.int16)
+    i = data2[0::2]
+    q = data2[1::2]
+    iq = i + 1j * q
+    iq = iq.reshape(-1, num_samples)
+    iq = iq + 1e-15
+
+    vmin = -60
+    vmax = 0
+
+    plt.figure()
+    plt.plot(np.diff(cpi_times))
+
+    plt.figure()
+    plt.plot(iq.T.real, '.-')
+    plt.plot(iq.T.imag, '--.')
+    plt.grid()
+
+    plt.figure()
+    plt.imshow(db20n(iq), aspect='auto', interpolation='nearest', vmin=vmin, vmax=vmax)
+    plt.ylabel('Pulse Count')
+    plt.xlabel('Sample Count')
+    plt.colorbar()
+
+
+    plt.show()
+
+
+if __name__ == '__main__':
+
+    main()