The Model 8210 Modulation Meter, manufactured by Boonton Electronics Corp., is a versatile, solid-state instrument that measures and displays the deviation of frequency-modulated signals or the percentage modulation of amplitude-modulated signals over a carrier range of 2 MHz to 1.5 GHz. Both the a.m. and f.m. detectors of the 8210 are true peak-responding at all levels. Thus they conform to the basic definition of modulation depth or deviation. in addition, because the detectors are true peak-responding, the effect of any system noise will be accurately included in the measured value. Among the features of the Model 8210 are: a. Fully Automatic Tuning and Leveling. The Model 8210 will automatically acquire the largest signal present at the input connector and adjust its local oscillator, and the gain of its measurement channel, to provide a fully calibrated display of amplitude modulation or frequency modulation. b. Internal Calibration. Each time it is turned on, the 8210 calibrates both its a.m. and its f.m. detector. c. Digital Display. The 8210 presents recovered modulation on a 3-1/2 digit display, providing exceptional resolution and accuracy for modulation measurements. d. Pushbutton Operation. Selection of all operational parameters is made by means of pushbuttons, thus allowing fast measurement setup. e. Low Residual Modulation. The 8210's exceptionally low residual modulation permits accurate measurements of low- noise sources. Direct residual measurements are possible if an external r.m.s. detector is used. The Model 8210 is intended for both laboratory and field application. It will also be especially useful in the design of, and for production-line and field-testing of, f.m. and a.m. transmitters and signal generators.