The GPS-89 (GPS-Rb) from Pendulum Instruments is a Time and Frequency Standard with Frequency 0.1 MHz / 5 MHz / 10 MHz, Stability over Temperature 30 ppb, Phase Noise -145 to -80 dBc/Hz, Short Term Stability 100 to 3000 ppb. Tags: Benchtop, Frequency Standard. More details for GPS-89 (GPS-Rb) can be seen below.