Variable voltage 1553 bus output linearity

The variable voltage output of the PCI-1553 and all of our other variable voltage boards is not a calibrated, absolute level. The variable voltage function allows the user to attenuate, in terms of a percentage, the maximum output. Furthermore, the voltage output is slightly non-linear at low output levels.

The non-linear output is a function of the commercial 1553 transceiver hybrid and the external load. The output is not calibrated because the output level depends greatly on the external load. The external load is a function of the actual bus setup; the number of stubs and cable length, for example, greatly affect bus loading.