Operating Manual Vol 1 - ES Documentation

Bit Error Rate TestSMIQBLER TYPEDATA POLARITYDisplays the CRC type. Only the CRC_16_BIT type is supported at present.IEC/IEEE-bus command :BLER:SET:TYPE?Setting the data bit polarity.NORM Normal polarityINV Inverted polarityIEC/IEEE-bus command:BLER:SET:DATA[:POL] NORMCLOCK SLOPESetting the clock edge polarity.POS Rising edgeNEG Falling edgeIEC/IEEE-bus command:BLER:SET:CLOC[:POL] RISINFORMATION DATAENABLEUNITSetting the polarity of the DUT's DATA ENABLE signal.LOW The bits received at low level of the data enable signal areinterpreted as information bits.The bits received at high level of the data enable signal areinterpreted as checksum bits.HIGH The bits received at high level of the data enable signal areinterpreted as information bits.The bits received at low level of the data enable signal areinterpreted as checksum bits.IEC/IEEE-bus command :BLER:SET:DEN LOWSetting the unit for BLOCK ERROR RATE display.ENG Display in exponential notation, exponent -3 or -6SCI Display in scientific notation, i.e. normalized to one characterahead of the decimal point% Display of relative frequency in percentppm Display of relative frequency in parts per millionIEC/IEEE-bus command :BLER:UNIT ENG2.23.2.2 CRC PolynomialCCITT CRC 16 : G(x) = x 16 + x 12 + x 5 + x 1 is the only CRC polynomial currently supported.At the beginning of information data (marked by the edge of the DATA ENABLE signal) the shift registeris initialized with 0. All information bits are then shifted through the shift register. The CRC componentis then read into a second register and compared bit by bit with the result of the calculation.2.23.2.3 Measurement Result, Accuracy, Measurement TimeRange of valuesStatisticsThe measurement results for the block error rate (i.e. the quotient of erroneousblocks and total blocks) are normally between 10 -2 and 10 -4 . This means that a largenumber of blocks may have to be tested before an erroneous block occurs.Because of the large number of blocks involved the measurement time is usuallyvery long. Since 32-bit-wide counters are used for the total number of blocks and theerror bits, the maximum measurement time is 4.29 x 10 9 blocks.The BLER measurement measures statistical block errors, i.e. errors which do notoccur at regular intervals but at random. Although a single measurementdetermines the exact number of errors in the measured interval, a statistically1125.5555.03 2.380 E-9