"The 8210 is a modulation meter from Boonton. Modulation meters measure degrees of modulation in a modulated signal.","Additional Features:","The Boonton 8210 is a used FM\/AM Modulation Meter. The Boonton 8210 is a microprocessor based high performance AM and FM modulation measuring instrument.The instrument provides automatic tuning and leveling, low residual modulation, true peak detection, a digital display, and self-calibration.To create modulation standards, the 8210 automatically generates two crystal-controlled frequencies to internally calibrate the FM channel, and two levels, differing by a precise amount, to calibrate the AM channel.The results are verified mid-range accuracies of 1% of reading for both AM and FM measurements, without the need for expensive external calibration setups."