The 3586A/B Selective Level Meter is designed for use in the design, manufacture, installation, and maintenance of Frequency Division Multiplex (FDM) systems and for general purpose wave analysis and frequency synthesis. The 3586A is available to meet the needs of C.C.I.T.T. requirements, while the 3586B meets North American (Bell) Standards. The 3586C is a general purpose instrument. The 3586A/B provides the ability to make both carrier frequency measurements to 32.5MHz and voice channel measurements from 50Hz to 100kHz. The Transmission impairments Option 003 allows the user to quickly troubleshoot voice channel problems with phase jitter, noise-with-tone, signal-to-noise-with-tone-ratio, and single level impulse noise measurements, all with one instrument. The capability to make all these transmission impairment measurements combined with both FDM voice channel and carrier frequency measurements is available only on the 3586A/B. Standard models include a 1740Hz psophometric or 2000Hz C-message equivalent noise filter, or weighted noise measurements can be made directly with the 3100Hz channel filter and noise weighting filter provided with the Transmission Impairments Option 003. Filter shape factor of < 1.2 provides 60dB carrier and 75dB adjacent channel rejection.