Said to rival standalone and VXI-based signal generators, NI 5431/5411/5401 signal sources are designed to deliver analog stimulus for performing network analysis, video signal testing, serial communications link testing, and more. The NI 5431 high accuracy analog and digital video signal generator is for PCI and PXI/CompactPCI computers and supports M-NTSC, B/G-PAL, M-PAL, N-PAL and SECAM standards. It also features a 20-MHz sampling frequency, adjustable over a 20.00 to 20.01 MHz range to support the chroma frequency of different formats. Price: $4995. Priced at $3495, the NI 5411 card is a full-featured arb for PCI, PXI/CompactPCI and ISA computers. It is said to include all of the functionality of arbitrary waveform, sweep and function generators. By contrast, the low-cost ($1495) MI 5401 is a DDS-based function generator for PCI and PXI/CompactPCI computers. It can generate repetitive signals, such as sine, square, triangular and limited arbitrary with a minimum frequency of 9.31 MHz.