APG PRS [PRS-017] True Echo Dual Frequency Pulse Radar Level Transmitter, 17ft (5m). The APG PRS series pulse radar level transmitter for Solids brings the unassailably accurate level readings of radar sensors to difficult to measure solids. Whether powders or pellets, grains or granules, the True Echo PRS's dual frequencies to allow it to quickly and accurately read the complex reflections from piled solids. The True EchoTM also automatically adjusts signal power for optimal accuracy and clarity. With echo masking and damping factors programmable via software, getting dependable level readings from difficult materials is simple.