Belar FMS-2 FM Precision Stereo Modulation Monitor


Belar FMS-2


The Belar Model FMS-2 Stereo Modulation Monitor is an all solid state precision stereo monitor designed to operate in conjunction with the Belar model FMM-2 baseband modulation monitor. The FMS-2 is also used for test functions in conjunction with the model FMM-2 to ensure the proper performance of FM stereo transmitters. The test and measurement capability of the FMS-2 is further enhanced by the integration of two independent auto-ranging voltmeters allowing automatic measurement of channel separation and crosstalk, along with sub-carrier suppression and noise. For example, depressing the left and right channel buttons automatically registers the wanted and unwanted channel for instant separation measurements. A front panel hold button can be used to lock the autorange to the displayed range.



  • Two independent semi-peak modulation meters for simultaneous monitoring of left and right channels
  • Front panel switchable de-emphasis for noise measurements
  • Pilot alarm with front panel indicator
  • Outputs for audio proof-of-performance measurements
  • Two auto-ranging voltmeters with LED displays for 0 to -80 dB range measurements
  • Stereo separation measurement capability of over 70 dB at 15 kHz
  • High visibility rear-illuminated meters

MP-8 Meter Panel

Belar has a number of analog remote meter panels for use with Belar FM monitors. The MP-8 meter panel is designed for use with the FMM-2/FMS-2 FM Monitor set. It features 3 large backlit meters and all the LED’s as the FMM-2 and FMS-2 for easy remote monitoring. It is the same height as the FMM-2 (3 rack-units, or 5.25 inches).

Technical Specification

Technical Specification

Input Level          
4.2 V P-P (3.5 V P-P Opt) composite

Input Impedance    
220k ohms, unbalanced, BNC connector

Left Meter
total modulation, L + R, pilot or left channel modulation

Right Meter
pilot phase, L-R, 38 kHz suppressior or right channel modulation

Auto Range Attenuator  
0-60 dB in 10 dB steps, calibrated full range readings:  +3 to -80 dB

Modulation Meter Range    
0 to 133%

Modulation Meter Accuracy    
Better than 2% over entire range

Pilot Meter Accuracy     
0.5% (6% to 13% pilot modulation)

Left to Right
70 dB, 10 Hz to 15 kHz

Right to Left
70 dB, 10 Hz to 15 kHz

L+R to L-R
85 dB min

L-R to L+R
85 dB min

SCA to L + R
Greater than 90 dB

SCA to L- R
Greater than 90 dB

SCA Interference
Greater than 90 dB

Left and Right Channel Program Audio
+10 dBm, 600 ohms, balanced

Left and Right Channel Program Test
5 vrms,10k ohms, unbalanced

3 V P-P. 27k ohm source

Composite (less Pilot)
4 V P-P,2k ohm source

Audio Output Specifications:
Frequency Response, Left and Right
+0.25 dB, 50-15,000 Hz

Signal to Noise Ratio,   Left and Right
90 dB min

Harmonic Distortion    
0.01% max. 50-15,000 Hz

Intermodulation Distortion   
0.01% max (SMPTE)

Remote Outputs:
Left Meter, Right Meter, Pilot Indicator For interface to Model MP-8 remote meter panel

5 1/4″H x 10 1/2″D x 19″W (EIA Rack Mount)

Power Consumption    
15 watts, 117/234 VAC, 50/60 Hz

Shipping Weight  
17 Ibs

© Copyright 2000 Belar Electronics Laboratory, Inc. All rights reserved.

New in 2015 – 3 Year Factory Warrant to all Belar Products 

Product Resources

Product Resources

Belar FMS-2 Manual

Comments are closed.