Instrument Function
R&S
®
SMJ100A
188
Operating Manual 1403.7458.32 ─ 14
"Data"
The applied data signal was detected.
"No Data"
The applied data signal was not detected.
Only clocked-in signals are detected; if the clock signal is missing,
then data changes will also not be detected.
If the data is not detected despite the detected clock signal, this may
be caused by the following:
●
The signal from the DUT is missing.
●
The wrong impedance for the applied clock rate was selected
(see "Impedance" parameter).
●
The wrong threshold for the applied data signal was selected (see
Threshold parameter).
"Sync"
The measurement is synchronized.
"No Sync"
The measurement is not synchronized.
Generally, a measurement cannot be synchronized until a clock and
a data signal have been detected. If synchronization still does not
occur, this may be caused by the following:
●
The selected PRBS is not correct. For the bit error rate measure-
ment, the PRBS sequence on which the data is based must be
set on the bit error rate tester. If the PRBS is not correct, the BER
measurement cannot synchronize to the data (due to the incorrect
polynomial).
●
A wrong clock slope is used, which violates setup or hold times
(see "Clock Slope" parameter).
●
The travel times of clock and data are unfavorable (e.g. clock
slope at data change). Check the relationship of clock to data
using an oscilloscope and optimize the travel times (e.g. clock
slope when the data signal applied is stable).
●
Reflections on the clock line occur, clocking the data signal into
the BER measurement twice, e.g. on lines without termination.
The R&S
SMJ input is not terminated.
●
Incorrect polarity of data signal (or "Data Enable" signal).
In this case the PRBS cannot synchronize. Note that an inversion
of the output signal specified for some cases by the PRBS stan-
dard is performed automatically upon PRBS selection. Manual
inversion of the data signal is therefore not required.
No Sync status and an error rate of approx. 50%:
●
A bit error occurs during synchronization (e.g. nine data bits with
PRBS9). The BER measurement is set up incorrectly. This fault is
internally detected and automatically corrected.
●
If data that is not cyclically continued (i.e. when a break in the
sequence occurs at the memory wrap-around), the measurement
will not be started at the right time. The signal on the "Restart"
line enables the measurement to be started optimally at the
beginning of the sequence.
Remote command:
Bit and Block Error Rate Measurements - BERT Block
Summary of Contents for SMJ100A
Page 34: ...Preface R S SMJ100A 18 Operating Manual 1403 7458 32 14 Notes on Screenshots...
Page 86: ...Preparing for Use R S SMJ100A 70 Operating Manual 1403 7458 32 14 LXI Configuration...
Page 826: ...Remote Control Commands R S SMJ100A 810 Operating Manual 1403 7458 32 14 UNIT Subsystem...
Page 828: ...Maintenance R S SMJ100A 812 Operating Manual 1403 7458 32 14 Storing and Packing...
Page 844: ...Hardware Interfaces R S SMJ100A 828 Operating Manual 1403 7458 32 14 BERT Connector...