Last updated: 16/11/2024

To synchronise a master device (SDRLab 122.88) and a slave device (SDRLab 122.88, externally-clocked version), you need to have the following connections.

One end of a SATA cable needs to be removed, along with its shield, to expose the inner wires. Once these are stripped, the ends can be soldered to pin headers or a connector as shown below. The connector or headers need to be plugged into the slave SDRLab as shown. NOTE: the polarity matters, since if it is incorrect, the trigger could jitter slightly by one clock cycle.

The master provides a ‘trigger out’ signal on DIO2_P, and the slave accepts a trigger input on DIO8_N.

[ NOTE this is inconsistent with both the Red Pitaya pinout diagram and the diagram on the ‘DACs’ page. This is still to be fixed.]

On the master, connect a jumper wire to DIO2_P and run it to DIO8_N on the slave, as shown below:

As shown in the ‘Trigger connection’ diagram above, there are two ground pins at the top of the pin header where the triggers connect. Each device in your MIMO setup should be connected together through these, to avoid floating grounds affecting the reliability of the clocks.

A chain of connections or a star ground are both fine.

Warning: Do not rely on the RF connections to ground your devices, since they may be floating (depending on the device and channel). A dedicated ground connection should be used.

If you are setting up the system and testing its synchronisation, connect the master and slave with two matching SMA-SMA cables (of identical type and length) to carry out cross-loopback testing: