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FM Modulation Monitor

From: Inovionics Broadcast
  • Weight:14 lb

  • Shipping Dimensions:3½ x 19 x 12” in

-Complete set of metering and measurement tools to ensure FM broadcast regulatory compliance worldwide.
-Separate inputs for Antenna, High Level ʻdirectʼ RF, and composite signal measurements.
-Full-time display of Signal Strength and Multipath effects, plus Synchronous AM noise output (BNC) to validate readings and aid in antenna alignment.

Incorporating all the necessary features for station setup, regulatory compliance, and remote monitoring, Inovonics' 531N is the ultimate choice for essential FM signal monitoring. Dependable, direct input and off-air reception lets you keep a sharp eye on your total RF signal performance whether you’re right at the transmitter site or half way around the world.

The high-resolution LED bargraph displays are easy to read, and a "floating dot" program peak marker eliminates any ambiguity in the total-mod measurement. Off-air readings are qualified by Inovonics' exclusive multipath indicator, which also aids in antenna alignment during initial station build-outs. In addition, readouts of signal strength and synchronous AM noise qualify the incoming signal and validate measurements. Rear-panel alarms constantly check for Audio Loss, RF Loss, Multipath and Overmodulation, while advanced notifications alert personnel with e-mail or SMS messaging when any or all of the alarms occur.


-Type: Double-conversion superhet circuit with proprietary ultra-linear, noise-rejecting pulse-counting FM detector.
-Tuning Range: 87.9MHz to 108.1MHz in 100kHz increments.
-Station Presets: 6 user-programmable pushbutton presets; local or remote selection.
-RF Inputs: 1) F connector for 75-ohm antenna. 2) BNC connector for high-level 50-ohm RF sample; 1V - 7V r.m.s.
-Receiver Sensitivity: 10µV (10dBf) for 50dB mono quieting; 250µV (60dBf) required for valid Total Modulation reading.
-Receiver Selectivity: ±0.25dB, 20Hz - 50kHz; –1.5dB or less at 100kHz (see Figure 1); –35dB (typ) at 200kHz (see Figure 2).
-Baseband Output: BNC composite/MPX demod output; 3Vp-p at 100%-modulation. RSSI (Incoming Signal Level): Independent front-panel LED bargraph metering of the relative strength of the incoming carrier. Multipath Distortion Measurement: Independent front-panel LED bargraph metering of the relative degree of multipath reception-distortion effects.
-AM Noise Measurement: Front-panel metering may be switched to show the relative level of the incidental, synchronous AM noise component of the FM carrier. AM noise is routed to a separate BNC output and also monitored by headphones when selected.