Campbell Scientific 18-bit binary format decode

binary1.dat

jSO@_`@Be@@T@@qB\P@@@@Ao@B@@@@@RpjSK@Be@]lLPE@_`@BeTWUDsIC$l@BD@@C@@C@DX@En@BS@I~$~z@@@@ND@@F@@|LPE@_`@BeSWGBhG}cqLPE@_`@BeSXMBhG}cqLPE@_`@BeSYRBhG}cqLPE@_`@BeSZXBhG}cqLPE@_`@BeS[]BhG}cqLPE@_`@BeS\cBhG}cqLPE@_`@BeS]hBhG}cqLPE@_`@BeS^nBhG}cqLPE@_`@BeS_sBhG}cqLPE@_`@BeS`xBhG}cqLPE@_`@BeSa~BhG}cqLPE@_`@BeScCBhG}cqLPE@_`@BeSdIBhG}cqLPE@_`@BeSeNBhG}cqLPE@_`@BeSfTBhG}cqLPE@_`@BeSgYBhG}cqLPE@_`@BeSh_BhG}cqLPE@_`@BeSidBhG}cqLPE@_`@BeSjiBhG}cqLPE@_`@BeSkoBhG}cqLPE@_`@BeSltBhG}cqLPE@_`@BeSmzBhG}cqLPE@_`@BeSn$BhG}cqLPE@_`@BeSpEBhG}cqLPE@_`@BeSqJBhG}cqLPE@_`@BeSrPBhG}cqLPE@_`@BeSsUBhG}cqLPE@_`@BeStZBhG}cqLPE@_`@BeSu`BhG}cqLPE@_`@BeSveBhG}cqLPE@_`@BeSwkBhG}cqLPE@_`@BeSxpBhG}cqLPE@_`@BeSyvBhG}cqLPE@_`@BeSz{BhG}cqLPE@_`@BeS|ABhG}cqLPE@_`@BeS}FBhG}cqLPE@_`@BeS~KBhG}cqLPE@_`@BeS$QBhG}cqLPE@_`@BeT@VBhG}cqLPE@_`@BeTA\BhG}cqLPE@_`@BeTBaBhG}cqLPE@_`@BeTCgBhG}cqLPE@_`@BeTDlBhG}cqLPE@_`@BeTErBhG}cqLPE@_`@BeTFwBhG}cqLPE@_`@BeTG|BhG}cqLPE@_`@BeTIBBhG}cqLPE@_`@BeTJGBhG}cqLPE@_`@BeTKMBhG}cqLPE@_`@BeTLRBhG}cqLPE@_`@BeTMXBhG}cqLPE@_`@BeTN]BhG}cqLPE@_`@BeTOcBhG}cqLPE@_`@BeTPhBhG}cqLPE@_`@BeTQmBhG}cqLPE@_`@BeTRsBhG}cqLPE@_`@BeTSxBhG}cqLPE@_`@BeTT~BhG}cqLPE@_`@BeTVCBhG}cqLPE@_`@BeTWIBhG}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cqjSI}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cq}cqjSM@`F@@A@@@Aqq@@@@m~Ap]B^b}cq}cq@qV@qC@DF@BeE`N@Dv@BvEYV@@d@`@@@A@@@Aqu@@@@ngAtHB^d}cq}cq@qw@qe@Fy@D]Dts@GR@DxDtu@@d@_z@@A@@@Aqz@@@@oBAt[B^e}cq}cq@rY@rI@Gj@E]D`i@HV@EzD`c@@d@_t@@A@@@Aq$@@@@oBAutB^e}cq}cq@r~@rk@Gb@C|DED@H@@D]DF\@@d@_n@@A@@@ArE@@@@oaArxB^e}cq}cq@sd@sH@FY@B`ELQ@FX@B|ESC@@d@_h@@A@@@ArJ@@@@p]AoIB^e}cq}cq@tK@sd@Bf@@xE\F@B|@ATEct@@d@_b@@A@@@ArP@@@@phAnQB^d}cq}cq@tq@tD@C~@B]Brj@Df@B{Bwf@@d@_\@@A@@@ArU@@@@pvAnoB^c}cq}cq@uX@t_@Cg@AqB\$@DF@BRBWM@@d@_V@@A@@@Ar[@@@@qJAm~B^a}cq}cq@u$@t~@C~@ALChT@DP@AbCNQ@@d@_P@@A@@@Ara@@@@qeAhLB^c}cq}cq@va@uX@Bx@ALDqO@B|@AcDqo@@d

decode.py

def decode_binary_message(bites):
    """
    Takes Cambell Scientific High Resolution 18-Bit Binary Format and converts
    it to a CSV row.
    """
    row = []
    while True:
        # Number are three bytes long
        byte_s = bites.read(3)
        if not byte_s:
            break
        # logger.debug('Bytes: {}'.format(byte_s, type(byte_s)))
        members = []
        for i, b in enumerate(byte_s):
            # binary = '{0:08b}'.format(b)
            # logger.debug('Binary {}: {}'.format(i, binary))
            # Apply mask to remove first two bits
            mask = 0b00111111
            masked = mask & b
            masked_bin = '{0:08b}'.format(masked)[2:]
            # logger.debug('Masked {}: {}'.format(i, masked_bin))
            members.append(masked_bin.encode())
        sofar = b''.join(members)
        # logger.debug('Combined mask: {}'.format(sofar))
        integ = int(sofar, 2)
        # This correct subtracts one and takes the complement if
        # the value should be negative per the Campbell Scientific docs
        # It's a typical two's complement
        # http://stackoverflow.com/a/9147327
        bits = 18
        if (integ & (1 << (bits - 1))) != 0:
            integ = integ - (1 << bits)
        row.append(str(integ))

    return ','.join(row)

with open('binary1.dat', 'rb') as f:
    print(decode_binary_message(f))