Specifications

5-34

System Command Reference Section

Error Detector Error Location

The Error Location features of the error detector have three forms, all of which may be

used when the instrument has any RAM-based pattern configured, i.e. the functions are

not available when any one of the five pure PRBS patterns is selected. The three forms

are: Bit BER, Error Location capture and Block BER.

Whole Pattern BER, Bit BER and Block BER are mutually exclusive operating modes of

the error detector. When in Block BER mode the bit error and clock counting functions

underlying the query commands in Error Detector Measurement Functions on page 5-36

are altered in accordance with the block start and length parameters. Pattern

synchronization is also affected.

In general Block BER is not measured on every repetition of the pattern. The number of

times a pattern will be repeated when configuring the pattern generator and detector

depends on the pattern length and is defined by table 4-2 of the Operating Manual. Where

it is important to make Block BER measurements on every repetition of the pattern the

pattern length must be set to a multiple of 256 bits.

SENSe[1]:ELOCation ONCE

This initiates an error location capture measurement. This is an overlapped command.

SENSe[1]:ELOCation?

The boolean response to this query command is true during an error location capture, and

false at all other times.

SENSe[1]:ELOCation:BEADdress <numeric value>

This command configures the single bit BER “BIT: Error address”

The query form of this command will only return the last configured value of the bit error

address provided no bit error has occurred (while a RAM pattern was selected) since the

last error location capture operation was started, for example, using the

“SENSe1:ELOC ONCE” command. Where a bit error has been captured the query

command returns the bit error address of the errored bit. This address is automatically

configured as the bit error address for the single Bit BER measurements. Thus when the

gated single Bit BER measurements are of interest, one would expect to re-start gating

after any error location capture had fired.