For example: Agilent E4440A or Anritsu 68369
National Instruments VXI
National Instruments 777119-32
VXI MXI-2 Interface for PCI / VXI-PCI8015 Windows, No Cable
Manufacturer: National Instruments
National Instruments 780531-01
NI VXIPC-882 Core 2 Duo 2.16 GHz Controller, Win XP FES
Manufacturer: National Instruments
National Instruments VXI-1394-G
IEEE 1394 Remote Controller W/ GPIB
Manufacturer: National Instruments