The three primary switching signals are SigRef , Cal , and Blanking . All backends can generate these signals and the LO1, receivers, and some backends can respond to various subsets of the signals. When using multiple backends only one backbend can generate the signals, i.e., be master, and the other must be slaves. However, this results in only the master knows the definitions of the states of the switching signals in each phase. Each device specifies its switching signals' sequences differently including parameter name, type, and meaning as the following table shows.
Data types are in parentheses.
This is most important in the case of the slave devices, the LO1 system in particular. The problem here is that the slaves are all synchronized to a common wall clock, but the jitter in the software timing may be a few milliseconds. The solution which best conforms to the philosophy intent of Ygor is for devices to set their states for switching signals for the first phase prior to the start of scan and then allowing the first transition to occur after the scan starts between the first and second phases. Slaves are responsible for ignoring the transitions during a quiescent period, q, if necessary for the proper operation of the slaves. In practical terms for the GBT, this rule only affects the LO1 when slaved to the DCR because the LO1 is the only device sensitive to transitions of switching signals rather than their state and the DCR is the only device that generates transitions at the start of a scan.