222 Keysight M8000 Series of BER Test Solutions User Guide
4 User Interface - M8020A Display Views
•PRBS
In a looping sequence block, a PRBS patern is generated using the
specified sequence block length as a minimum number of bits and
increased to a full repetition of the base PRBS. As an example, a
PRBS7-1 with original length of 127 bits and a sequence block length
of 200 bits is given. This will generate a PRBS pattern with a length of
254 bits, meaning two PRBS7-1 iterations. These 254 bits are then
used as a base pattern for the generated waveform and multiplied as
required to fit into an AWG memory segment.
Non-looping patterns contain the number of sequence bits defined in
the sequence block and do not consider the natural PRBS repetition
length.
• Memory Pattern
For memory patterns, only the number of bits that are specified as
sequence block length, occur in the resulting pattern. In case the
memory pattern has a length of 200 bits while the sequence block
length is specified as 100 bits, only the first 100 bit of the memory
pattern will be used for generating the data stream.
• Static
Static segments use the number of bits in the sequence block, either
as a minimum repetition length for roll-out in looped sequence blocks
or for defining a minimum pattern length in non-looped sequence
blocks.
•Clock
The minimum number of clock symbols are defined by the least
common multiple of the clock divider setting and the number of bits
specified as sequence block length. In case the line coding is, for
example defined as PAM4, the number of bits of a clock sequence
block additionally needs to be divisible by the number of bits per
symbol which is 2 bit/symbol.
•Pulse
The pulse pattern considers the number of bits specified as sequence
block length as the minimum pattern length. The length of the pulse’s
high duration is thereby specified by the width property configurable in
the sequence block’s data properties. In case of a line coding
containing more than one bit per symbol, the pulse pattern width and
length must be a multiple of the bits per symbol value (For PAM4, this
value is 2 bit/symbol).