AM Modulation Analyzer with Network Interface

AM Modulation Analyzer
with Network Interface
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 amplitudemodulated component of HD Radio™
‘hybrid digital’ transmissions. The
525N is also compatible with powersaving MDCL operation.
Although the 525N maintains full
wideband response for measurement,
it features user-selectable audiomonitor 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 largeaperture, weatherproof loop antenna.
5805 Hwy 9, Felton CA 95018
• Accurate, simultaneous display of p
ositive and negative peak modulation
with Peak Density histogram
• Absolute-limit and user-programmable P
eak Flashers
• Calibrated RSSI signal strength display and asynchronous noise readout
• Alarms for Low Signal, Audio Loss and Overmodulation with panel indicators
and ‘tally’ closures
• Text message and/or email alarm alerts may be selectively dispatched to
multiple recipients
• Compatible with HD Radio transmissions and MDCL transmitter operation
• Full Web interface gives total remote control of all setup parameters,
metering, alarms with logging, and streamed audio monitoring
• Easy menu-driven setup and
operation, or use the convenient Web interface
• 5 Station Presets
• 10kHz/9kHz channel spacing
• Balanced audio output
• Supplied with out-
door loop antenna
• Headphone jack
Remote Web Interface
Receiver Topology:
Single-conversion superheterodyne; 300kHz IF; phaselocked I/Q synchronous detector.
RF Inputs:
The 75-ohm (F) antenna input connects to the supplied
broadband 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) highlevel input accepts a direct RF sample between 1V and 7V
r.m.s. / 3V–20V p-p.
Tuning Range:
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.
Signal-to-Noise Performance:
(See Figure 1)
Measurement Bandwidth:
Carrier amplitude demodulation extends to 10kHz, ±0.2dB.
Measurement is not affected by the user-selectable audio cutoff.
Audio Response:
User-selectable “FLAT” response, or restricted in
programmable 1kHz steps between 10kHz and 2kHz.
(See Figure 2)
A menu command switches-in the NRSC ‘truncated’ 75µs
de-emphasis characteristic to the program audio outputs
with any restricted audio bandwidth selection. (See Figure 3)
Audio Distortion:
Typically 0.15% THD at 50% carrier modulation; <0.5% at
99% modulation.
Modulation Display:
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.
Peak Flashers:
• 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%.
Program Audio Outputs:
• 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 Monitoring
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
Power Requirements:
105–130VAC (0.250A Fuse) 210–255VAC (0.125A Fuse),
50/60Hz; 10W.
Size and Weight:
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.
RSSI and Noise Display:
The Modulation Display may be switched to show the
dBuV level of the incoming carrier (RSSI) and a relative
measurement of asynchronous noise.
Figure 1 plots the program audio
output noise floor against the RF
level at the antenna connector.
Signal-to-noise performance of
the 525N is a direct function of
the incoming RF level. The figures
shown reference 100% modulation
with 10kHz audio bandwidth and
NRSC de-emphasis.
Figure 1 - Model 525N
SNR Performance
Figure 2 illustrates the effect of
the menu-programmable audiocut filter in the program audio and
headphone outputs of the Model
525N. This filter does not affect
modulation measurements, which
always follow the FLAT response
noted, regardless of the audio
cutoff selected.
Figure 2 - Model 525N Off-Air Measurement Response (FLAT) a
nd Program-Audio Cutoff Options
Figure 2, above, does not reflect
the ‘truncated’ 75µs NRSC deemphasis characteristic graphed
here in Figure 3. De-emphasis
is a menu option that is normally
engaged to compensate for
complementary transmission preemphasis mandated by the 1985
NRSC Specification.
Figure 3 - NRSC De-Emphasis Curve for AM Broadcasting
Made in USA
5805 Hwy 9, Felton CA 95018
© Inovonics, Inc. March, 2016
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