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Clock and Trigger Synchronization of M4i.44xx and M4i.66xx series

Both card families can't be synchronized with the star-hub as this option only matches one card family. However external clock and trigger connections allows to synchronize the M4i.44xx and the M4i.66xx.

Clock Synchronization

Diagram of sync setupThe clock output of the M4i.66xx can be directly connected to the clock input of the M4i.44xx. The M4i.44xx uses this clock signal as a reference clock signal. The M4i.66xx cards output an internal system clock what is either 1/8 of the sampling clock or 1/4 of the sampling clock depending on the selected speed. This clock frequency needs to be programmed as reference clock of the M4i.44xx. The M4i.44xx then multiplies this clock to reach the digitizer sampling. For clock synchronization one needs a MMCX to SMA cable (availble from Spectrum)

An example:

  • M4i.6622-x8: sampling clock set to 500 MS/s -> clock output 500/8 = 62.5 MHz
  • M4i.4451-x8: reference clock input set to 62.5 MHz, sampling clock set to 500 MS/s -> sampling clock 500 MS/s, synchronous to M4i.6622-x8

Obviously there is some phase delay (and some aperture delay) between D/A and A/D card but that is fixed for a specific setup. While it is possible to set AWG and Digitizer to different sampling rates (like 625 MS/s and 500 MS/s) this will result in some phase uncertainity. Therefore it is strongly recommend to program both cards to a clock relation of a whole even number (1:2, 1:2, 1:4, ...)

It is possible to either synchronize single cards with each other or to synchronize a set of AWGs, synchronized by star-hub with a set of Digitizers, synchronized by a second star-hub.

Please note that when using the star-hub with the M4i.44xx the clock settings are restricted to the standard clock mode. The special clock mode which allows a fine setup clock granularity is only available for single clocks.

Trigger Synchronization

Trigger synchronization can be done on the same way. Connecting the trigger output of the M4i.66xx series to the trigger input of the M4i.44.xx series. Again a MMCX to SMA connection cable is needed here.

SBench 6

SBench 6 can only handle one set of cards in one software instance. To run synchronization of M4i.44xx and M4i.66xx with SBench 6 it is necessary to run two independent SBench 6 instances on the machine. A single Professional + a single Multi license is sufficient for this.



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