racerxdl / packet-finder.py

#!/usr/bin/env python import os, math import collections ''' Sync Words Phased 0 = 00011010 11001111 11111100 00011101 = 0x1ACFFC1D 1 = 10001111 01010101 01010110 10000100 = 0x8F555684 2 = 11100101 00110000 00000011 11100010 = 0xE53003E2 3 = 01110000 10101010 10101001 01111011 = 0x70AAA97B ''' ''' Sync Words 1/2 Symbols 0 = 00000011 11001100 11110000 11111111 11111111 11110000 00000011 11110011 = 0x03CCF0FFFFF030F3 1 = 11000000 11111111 00110011 00110011 00110011 00111100 11000000 00110000 = 0xC0FF3333333CC030 2 = 11111100 00110011 00001111 00000000 00000000 00001111 11111100 00001100 = 0xFC33F00000F0FCC0 3 = 00111111 00000000 11001100 11001100 11001100 11000011 00111111 11001111 = 0x3F00CCCCCCC33FCF 00000011 11001100 11110000 11111111 11111111 11110000 00000011 11110011 S = 00000011 10010010 11100011 01010100 11100111 10100111 11010100 00010101 11111100 00110011 00001111 00000000 00000000 00001111 11111100 00001100 F = 11111100 01101101 00011100 10101011 00011000 01011000 00101011 11101010 00000011 10010010 11100011 01010100 11100111 10100111 11010100 00010101 ''' ''' Frame Size = 1024 bytes (1020 + 4) Rate = 1/2 Frame Symbol Size = 1024 * 8 * 2 Input = IQ Byte. Symbol = 2 Byte Frame Input Size = 1024 * 8 * 2 * 2 ''' frameSymbolSize = 1024 * 8 frameInputSize = frameSymbolSize * 2 frameBitSize = frameSymbolSize * 2 syncWordSize = 32 syncWordDoubleSize = syncWordSize * 2 UW0 = 0x03CCF0FFFFF030F3 UW1 = 0xC0FF3333333CC030 UW2 = 0xFC33F00000F0FCC0 UW3 = 0x3F00CCCCCCC33FCF def processFrame(frameData, n): ''' Gets the bit array, corrects the phase ambiguity and returns a byte array frameData = bit array n = phase number(0 = 0, 1 = 90, 2 = 180, 3 = 270) ''' # Fix Ambiguity ''' p0 p1 p2 p3 00 10 11 01 01 00 10 11 11 01 00 10 10 11 01 00 ''' if n == 1 or n == 3: # 90 / 270 phase # We can just shift to 90 and if its 270 we invert the bits later for i in range(0, len(frameData), 2): a = 1 if frameData[i+1] == 0 else 1 b = 1 if frameData[i] == 0 else 1 frameData[i] = a frameData[i+1] = b if n == 2 or n == 3: # 180 / 270 is 0 / 90 inverted frameData = invertBits(frameData) # Generate byte array bdata = "" for i in range(0, len(frameData), 8): v = 0 for k in range(0, 8): v = v << 1 v = v | frameData[i+k] bdata += chr(v) return bdata def processFrameBitMap(frameData, n): ''' Gets the bit array, corrects the phase ambiguity and returns a byte array frameData = bit array n = phase number(0 = 0, 1 = 90, 2 = 180, 3 = 270) ''' # Fix Ambiguity ''' p0 p1 p2 p3 00 10 11 01 01 00 10 11 11 01 00 10 10 11 01 00 ''' if n == 1 or n == 3: # 90 / 270 phase # We can just shift to 90 and if its 270 we invert the bits later for i in range(0, len(frameData), 2): a = 1 if frameData[i+1] == 0 else 1 b = 1 if frameData[i] == 0 else 1 frameData[i] = a frameData[i+1] = b if n == 2 or n == 3: # 180 / 270 is 0 / 90 inverted frameData = invertBits(frameData) # Generate byte array bdata = "" for i in range(0, len(frameData)): bdata += chr(0xFF) if frameData[i] == 1 else chr(0x00) return bdata def invertBits(frame): for i in range(0, len(frame)): frame[i] = 1 if frame[i] == 0 else 0 return frame def binary(num, length=8): return format(num, '#0{}b'.format(length + 2)) def binStringToIntArr(b): if b[1] == 'b': b = b[2:] a = [] for i in b: a.append(int(i)) return a def symbolToBit(symbol): bdata = [] I = ord(symbol[0]) - 127 Q = ord(symbol[1]) - 127 if I > 0: bdata.append(1) else: bdata.append(0) if Q > 0: bdata.append(1) else: bdata.append(0) return bdata def checkCorrelationInBuffer(): uw0mc = 0 # Highest Correlation Factor for UW0 uw0p = 0 # Highest Correlation Position for UW0 uw1mc = 0 uw1p = 0 uw2mc = 0 uw2p = 0 uw3mc = 0 uw3p = 0 for i in range(0, frameBitSize - syncWordDoubleSize): uw0c = 0 uw1c = 0 uw2c = 0 uw3c = 0 # To get the highest correlation, we xor with the inverse of the word. So 180 phase for k in range(0, syncWordDoubleSize): uw0c += sbits[i+k] ^ UW2[k] uw1c += sbits[i+k] ^ UW3[k] uw2c += sbits[i+k] ^ UW0[k] uw3c += sbits[i+k] ^ UW1[k] uw0p = i if uw0c > uw0mc else uw0p uw1p = i if uw1c > uw1mc else uw1p uw2p = i if uw2c > uw2mc else uw2p uw3p = i if uw3c > uw3mc else uw3p uw0mc = uw0c if uw0c > uw0mc else uw0mc uw1mc = uw1c if uw1c > uw1mc else uw1mc uw2mc = uw2c if uw2c > uw2mc else uw2mc uw3mc = uw3c if uw3c > uw3mc else uw3mc return uw0p, uw0mc, uw1p, uw1mc, uw2p, uw2mc, uw3p, uw3mc UW0 = binStringToIntArr(binary(UW0, syncWordDoubleSize)) UW1 = binStringToIntArr(binary(UW1, syncWordDoubleSize)) UW2 = binStringToIntArr(binary(UW2, syncWordDoubleSize)) UW3 = binStringToIntArr(binary(UW3, syncWordDoubleSize)) f = open("test.s", "r") fsize = os.path.getsize("test.s") o = open("test.s.out", "w") ob = open("test.s.outbit", "w") sbits = collections.deque(maxlen=frameBitSize) count = 0 fcount = 0 print "Frame Input Size: %s" %frameInputSize while count < fsize: ''' Read the data from input to sbits ''' data = f.read(frameInputSize) for i in range(0, frameInputSize, 2): b = symbolToBit(data[i:i+2]) sbits.append(b[0]) sbits.append(b[1]) ''' Search for the sync word using correlation ''' uw0p, uw0mc, uw1p, uw1mc, uw2p, uw2mc, uw3p, uw3mc = checkCorrelationInBuffer() mp = max(uw0mc, uw1mc, uw2mc, uw3mc) print "Frame: #%s" %fcount print "Max Correlation: %s" %mp if mp == uw0mc: print "Max Correlation with 0 degrees Word at %s" % uw0p n = 0 p = uw0p elif mp == uw1mc: print "Max Correlation with 90 degrees Word at %s" % uw1p n = 1 p = uw1p elif mp == uw2mc: print "Max Correlation with 180 degrees Word at %s" % uw2p n = 2 p = uw2p elif mp == uw3mc: print "Max Correlation with 270 degrees Word at %s" % uw3p n = 3 p = uw3p ''' Read p bits for syncing the Circle Buffer Each pair of bits come from 2 bytes of the input So we will read 1 byte per bit ''' #t = p if p % 2 == 0 else p + 1 #data = f.read(t) #for i in range(0, t, 2): # b = symbolToBit(data[i:i+2]) # sbits.append(b[0]) # sbits.append(b[1]) print "B: " + str(list(sbits)[p:p+64]) print "W: " + str(UW0) ''' Now we should have everything in sync ''' #frame = processFrame(list(sbits), n) #o.write(frame) #frameb = processFrameBitMap(list(sbits), n) #ob.write(frameb) fcount += 1 count += frameInputSize #+ t ''' Clean everything ''' f.close() o.close() ob.close()