The 525N is a third-generation AM Modulation Monitor from Inovonics. It can accept either a direct feed from the transmitter, or function as a precision Reference Receiver to give accurate off-air measurements reflecting ATU, phasor and antenna parameters.
A proprietary phase-locked synchronous detector provides precise demodulation, rejects interference, and recovers only the amplitude-modulated component of HD Radio™ ‘hybrid digital’ transmissions.
The 525N is also compatible with power-saving MDCL operation. Although the 525N maintains full wideband response for measurement, it features user-selectable audio-monitor cutoff characteristics to mitigate noise or to simulate the response of consumer radios.
IP connectivity with full SNMP support gives the user total access to the unit from any computer, tablet or mobile device. Setup, metering, alarms and audio monitoring are all available from the remote monitoring point.
The 525N is supplied with a large-aperture, weatherproof passive AM Loop Antenna.
- Alan Alsobrook Checking it Out - Inovonics 525N AM Modulation Monitor
Single-conversion superheterodyne; 300kHz IF; phase-locked I/Q synchronous detector.
The 75-ohm (F) antenna input connects to the supplied broadband passive AM Loop Antenna. Cable is not included, but up to 100 feet of general-purpose RG-6 CATV coax may be used. A short wire antenna may prove adequate in high-signal areas that suffer minimal interference. A 50-ohm (BNC) high-level input accepts a direct RF sample between 1V and 7V r.m.s. / 3V–20V p-p.
Tunable via the front-panel menu or the Web interface:
520kHz to 1720kHz in 10kHz steps
522kHz to 1719kHz in 9kHz steps Five station-memory pushbutton/Web presets are provided.
Carrier amplitude demodulation extends to 10kHz, ±0.2dB. Measurement is not affected by the user-selectable audio cutoff.
User-selectable “FLAT” response, or restricted in programmable 1kHz steps between 10kHz and 2kHz.
A menu command switches-in the NRSC ‘truncated’ 75μs de-emphasis characteristic to the program audio outputs with any restricted audio bandwidth selection.
Typically 0.15% THD at 50% carrier modulation; <0.5% at 99% modulation
The peak-responding front-panel bargraph readout shows positive and negative modulation peaks simultaneously, with extended persistence of the most recent highest peak value. Measurement resolution is 1% between 50% and 100% (negative) and 50% and 140% (positive) modulation, and 2% between 20% and 50% modulation.
The Modulation Display may be switched to show the dBuV level of the incoming carrier (RSSI) and a relative measurement of asynchronous noise.
Absolute-limit flashers are factory-calibrated at –100% and +125% carrier modulation.
A second set of flashers may be programmed by the user to values between –70% and –100%, and +70% and +140%.
The active-balanced, rear-panel program audio output (XLR) delivers +4dBu from a 200-ohm resistive source.
Front-panel headphone jack (¼-inch, TRS)
Open-collector NPN transistor outputs (screw-terminal block) for low signal, program audio loss and overmodulation. Closure polarity is programmable.
RJ45 jack for remote setup and operation via TCP/IP; DHCP or Static IP with local or remote selection
Remote Web-based monitoring of off-air audio
Comprehensive network configuration utility including dynamic DNS and full SNMP support with downloadable MIB file.
Supports email and text message services with or without SSL.
105–130VAC (0.250A Fuse) 210–255VAC (0.125A Fuse),50/60Hz; 10W.
1¾”H x 19”W x 7”D (1U); 9 lbs. (shipping).
0°C – 50°C operating temperature range; 95% noncondensing relative humidity; up to 3000 meters AMSL