Two power sensor inputs for multi-port measurement Ratio mode for measuring gain compression Programmable high and low power limits for unattended power monitoring Measurement Modes: A, B, A-B, B-A, A/B, B/A Uses 8480 Series Power Sensors GPIB Interface The 438A power meter is a dual-channel power meter designed specifically for ATE systems. The compact front panel saves critical rack space, while the dual-channel design allows simple and accurate measurements of the ratio and difference of power levels from two separate sensors.