OFF-AIR RECEIVER SECTION
Type
Double-conversion superhet circuit with proprietary ultra-linear, noise-rejecting pulse-counting FM detector
Tuning Range
76MHz – 108MHz in 100kHz increments
Station Presets
6 user-programmable pushbutton presets; local or remote selection
- F connector for 75-ohm antenna
- 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.
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.
FM BASEBAND MEASUREMENTS
Adjustable BNC composite/MPX input to stereo decoder and subcarrier measurement circuitry. Accepts 100%- modulation levels (typical 3V p-p) equating to ±75kHz carrier deviation.
Composite/MPX Metering
58-segment LED bargraph display has quasi-peak response with floating peak hold. Switchable between positive deviation, negative deviation and highest of either
Meter Resolution
1% accuracy between 80% and 100% carrier modulation; 2% resolution between 46% and 80% (100% = ±75kHz carrier deviation)
Metering Integration
User-selectable at 0.1ms, 0.2ms, 0.5ms and 1.0ms
Meter Frequency Response
+0/–1%, 10Hz - 100kHz
Peak Flasher
Programmable in 1% increments between 95% and 120% of total carrier modulation.
- Direct connection to the demodulated output of the offair receiver section
- BNC connector accepts an external baseband input 3V p-p (adjustable) equivalent to full (±75kHz) carrier deviation
Program Audio Outputs
- Balanced XLR Left & Right channel stereo program outputs deliver +4dBm at 100% monaural modulation (±75kHz carrier deviation)
- Front-panel headphone jack
Demod Metering Display
Dual LED bargraph displays show Left and Right or L+R and L–R demodulated program audio. The display is peak responding between +10dB and –30dB, and average responding between –30dB and – 64dB.
Stereo Audio Frequency Response
±0.5dB, 10Hz - 15kHz
Stereo Signal-to-Noise Ratio
Unmodulated (stereo) carrier noise is better than 65dB below 100% modulation with de-emphasis applied.
Distortion
<0.075%THD at 400Hz 100% Modulation Mono. No De-Emphasis, unweighted
Stereo Separation
55dB, 50Hz - 15kHz with an external composite/MPX input. In the off-air mode, receiver selectivity limits separation to >45dB, 50Hz - 15kHz (see Figure 3).
Stereo Crosstalk
By the M/S or S/M (stereo-difference) method, >60dB, 50Hz - 5kHz, derated to >45dB at 15kHz with external composite/MPX input. In the off-air mode receiver selectivity limits crosstalk to >50dB, 50Hz - 5kHz, derated to >35dB at 15kHz (See Figure 4).
Stereo/Mono Switching
Mode switching is automatic with a front-panel indicator; monaural reception may be forced with a front-panel button or from the remote Web Interface.
Program De-Emphasis
May be turned on and off from front panel or Web Interface (indicator provided); internal jumper selects 50μs or 75μs characteristic.
FM SUBCARRIER MEASUREMENTS
Meter Scaling and Resolution/Accuracy
58-segment LED bargraph display measures stereo pilot and subcarrier levels between 2.6% and 14% with 0.2% resolution and accuracy. Injection percentages refer to 100% = ±75kHz carrier deviation.
Metering Characteristic
Peak-responding in all modes
Measurement Filters
- 19kHz Stereo Pilot Tone
- 38kHz Residual Stereo Subcarrier
- 57kHz RDS/RBDS Data Subcarrier
- 67kHz SCA Audio Subcarrier
- 92kHz SCA Audio Subcarrier
PROGRAMMABLE ALARMS
Peak Flasher
Ground-closure output gives remote indication coincidental with the front-panel Peak Flasher
Program Audio Loss
Front-panel LED and ground-closure (remote) alarm is programmable from the front panel to indicate when either stereo channel remains 10dB or more below 0dB for a period that may be set between 10 seconds and 2 minutes.
Low Signal
Front-panel LED and remote ground-closure alarm is fixed at a level of incoming RF signal below which modulation measurements are not valid.
Multipath
Front-panel LED and remote ground-closure alarm is fixed at a degree of multipath distortion above which modulation measurements are not valid.
NETWORK PORT
Rear Panel Connector
An RJ45 jack accepts TCP/IP Network Connections for remote setup and operation.
Settings
DHCP or Static IP address can be set from the front panel.
SNMP
Supports SNMP remote monitoring and control (MIB file can be downloaded directly from the 531N)
SMTP
Supports email services with or without SSL.
Dynamic DNS
Supports dyndns.org, no-ip.org, and dnsomatic.com.
MISCELLANEOUS
Power Requirements
105 - 130VAC or 210 - 260VAC, 50/60Hz; 20 watts
Size and Weight
3½”H x 19”W x 12”D (2U); 14 lbs. (shipping)
Environmental
Continuous operation at ambient temperatures between 32ºF/0ºC and 122ºF/50ºC; 0-95% relative humidity, non-condensing, altitudes to 10,000ft/3,048m.
