552 FM & HD Radio Modulation Monitor

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Integrating all the necessary features for station setup, regulatory compliance, and remote monitoring, Inovonics’ 552 HD Radio Modulation Monitor is the ideal choice for advanced FM and HD Radio signal monitoring. Simultaneously monitor in real time the off-air FM modulation along with up to 4 HD Radio Channels.

The 552 collects a history of signal parameters and displays HD Radio™ album artwork, station logos and similar visuals on the remote Web interface. The 552 includes a built-in BandScanner™, a real-time clock and full SNMP functionality

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. SNMP is fully supported.


  • Monitor off-air analog FM and HD Radio signals (HD1-HD8) remotely via any Web enabled device.
  • Spectrum graphs include RF Baseband, MPX and Left/Right Audio. O-Scope views for MPX, Pilot, RDS and all Audio Channels.
  • The 552 collects a history of signal parameters and displays HD Radio™ album artwork, station logos and similar visuals via remote Web interface.
  • Measures real-time audio diversity delay between the FM and HD1 broadcast.
  • Fulltime off-air program audio is available simultaneously as L/R-analog, AES3-digital and Dante®-based AES67 AoIP streaming, all with adjustable levels, plus a multi-listener Internet IP stream and front-panel headphone jack.
  • StationRotation enables the user to monitor up to 30 different Station Presets.


Tuning Range: 87.5MHz-107.9MHz in 100kHz steps
Antenna Input: 75-ohm (F)
High Level RF Input: 50-ohm (BNC)
Sensitivity/SNR: 10dBuV required for 50dB mono-FM SNR, unweighted.
Reception Modes: FM: Stereo / Forced Mono
HD Radio: HD1 through HD8
FM/HD1: ‘Split Mode’ delivers L+R FM to the left audio channel and L+R HD1 to the right.
Off-Air Frequency Response: FM: ±.1dB, 20Hz-15kHz
HD Radio: ±0.25dB, 20Hz-20kHz
Stereo Separation: FM: 60dB, 20Hz-15kHz
HD Radio: 90dB, 20Hz-20kHz
Distortion: FM: <0.01% THD, 20Hz-15kHz
HD Radio: <0.003% THD, 20Hz-20kHz
FM De-emphasis: 75µs, 50µs or None, menu-selectable
Program Audio Outputs: ‘Assignable’ outputs utilize XLR connectors.
Balanced Analog: Left and Right outputs adjustable from –15dBu to +15dBu in 0.1dB steps; 200Ω source.
AES Digital: Adjustable from –30dBFS to 0dBFS in 0.1dB steps; 44.1kHz sample rate; 110 Ω transformer-coupled.
Dante/AES67 Compatible: (RJ45) Output at 44.1kHz (Dante-only) or 44.1kHz/
48kHz (Dante /AES67); AoIP utility has independent IP, Audio Format and Transmit Flow settings; level adjustable from –30dBFS to 0dBFS in 0.1dB steps.
Headphone Jack: (¼” TRS) with adjustable listening level.
Listening Stream: Web browser ‘remote listening’ stream uses HE-AACv2 encoding, 44.1kHz or 48kHz sample rate, bit-rates from 18kbps to 64kbps; accommodates up to 10 simultaneous listeners. HTTP/Icecast and raw UDP streams are available simultaneously.
Composite/MPX Output: (BNC) may be switched between MPX and 19kHz stereo pilot sample; adjustable from 1Vpp to 6Vpp in 0.05V steps.
LAN Port: LAN connection to local network or Internet provides remote monitoring, control, listening and full SNMP implementation; user-programmable network setup and streaming parameters.
General Purpose Outputs: Ten individual open-collector NPN transistor closures to ground are associated with alarm functions. Each is programmable for GPO assignment and logic polarity.
RDS Fields Displayed ## (Web only): PS • PI • Call • RT • RT+1 • RT+2 • PTY • PTYN • CT • M/S • DI • TP • TA • AF • ODA • Block Error Rate • Groups & use statistics.
HD PAD Data Displayed ## (Web only): Overview: Short Name • Universal Name • Station ID • Slogan• Message • Station Location • Service Mode • TX Blend • Emergency Alert
HD1-HD8, each: Slogan • Program Type • Artist • Title • Album • Codec Mode • Bitrate • TX Gain • Logo/Artist Experience graphics and file details.
Bargraph & Numerical Level Metering: Analog FM: Carrier Modulation • Stereo Pilot & Subcarriers • Demodulated L/R & L+R/L-R • Stereo Separation • Stereo Crosstalk • BS.1770 Loudness • Synchronous & AM Noise.
HD Radio: (simultaneously for HD1 and three other preselected HD programs)
L/R Audio • BS.1770 Loudness (absolute and relative to Analog FM Loudness).
FM/HD1 Alignment: Timing offset and level and phase discrepancies between programs; ‘Confidence Factor’ display.
Graphic Displays/Plots ## (Web only): RF Spectrum • MPX Spectrum • Audio Spec­trum • Audio XY • Audio O’scope • FM Modulation History • Audio Level History • Metrics History • FM/HD1 Time & Level Alignment History • BandScanner™ utility.
Alarms: Most alarms have multiple parameter settings. All alarms can send text or email notifications. Alarms are also logged: daily, weekly, monthly.
Analog FM: Carrier Overmod • Audio Loss • Low Signal • RDS Loss • PI Error • RT Update • Pilot Loss
HD Radio: HD Loss • Program Loss • Audio Loss • HD Power Level • FM/HD1 Alignment • PSD Update • Logo Receipt • Artist Experience Update • Image Issues • Emergency Alert Updates
Real-Time Clock: Auto-sets to Internet time; auto/manual DST setting; battery backup.
Power Requirement 88-264Vac, 18W.
Dims and Weight 63.6cm H x 43.2cm W x 7.6cm D; 3.6kg shipping weight.