BELAR MODEL TVM-250 SAP/PRO MONITOR
DESCRIPTION
The Belar TVM-250 SAP/PRO monitor is a dual modulation monitor system for television stations broadcasting the MTS Second Audio Program (SAP) and/or PROfessional channels. Operated in conjunction with the Belar TVM-100, TVM-101, or other wideband aural demodulator, the Belar TVM-250 combines simultaneous demodulation and peak modulation measurement of both SAP and PRO subcarriers. An internal RMS metering system indicates injection of both subcarriers and provides direct RMS readings of audio crosstalk and signal-to-noise ratios.
Accurate decoding of the encoded SAP signal is assured by an on-board professional dbx expander card. A crystal-controlled calibration system provides precise references for SAP and PRO carrier deviations, injection levels, and dbx expander performance. SAP and PRO rear-panel audio outputs are active-balanced and drive 600-ohm lines at +10 dBm.
The Belar TVM-250 SAP/PRO Monitor combines all its functions in a single chassis only one rack unit high. Two large LED displays simultaneously indicate peak modulation percentage of the SAP and PRO channels. Four LED's indicate modulation peaks and presence of the SAP and PRO channels, with user-adjustable thresholds. All operational and metering functions can be controlled via the front-panel menu system. One set of UP/DOWN keys provides menu control, another set of keys adjusts operating parameters. Adjustable parameters include peak flasher settings and muting thresholds for SAP and PRO. To facilitate broadcast performance measurements, the menus offer the capability to bypass the subcarrier bandpass filters, to change the SAP detector bandwidth, and to substitute 75 micro-second de-emphasis for dbx companding.
The Belar TVM-250 SAP/PRO Monitor provides an RS-232 output, permitting full operation and readout under computer control. With the addition of a 2400-bps modem and the supplied Wizard software, computer control may be from any off-site location via a standard telephone line. The TVM-250 may also be used in conjunction with other Belar monitors via the Wizard interface. The Wizard system turns an ordinary PC into a powerful tool for display and logging of SAP and PRO modulation parameters
The Wizard Software can operate the TVM-250 remotely and is also used to display real-time graphs. A direct connection or a pair of modems and a phone line may be used. The software is fully password protected with three levels of access. (Software available 1Q97)
Input wide-band demodulated aural composite
Input Level 400 mV to 4Vrms for 73 kHz peak deviation
Audio Outputs
Balanced Outputs +10 dBm, 600 active-balanced, XLR-type connectors
Test Outputs 5 Vrms, unbalanced, BNC connectors (75 ohm source)
Audio Test (auto-ranged) 1.2Vrms, unbalanced, BNC connector (75 ohm source)
Serial Interface RS-232
Unit Interface Wizard Standard Interface
Remote Meter Outputs:
SAP Analog Modulation Meter
PRO Analog Modulation Meter
Open collector and relay closures for SAP and PRO peak modulation and carrier presence ndicators
Data Out - direct coupled PRO demodulator output. 0.9Vrms at 3kHz peak deviation.
SAP Specifications (20 Hz - 10 kHz):
Subcarrier Peak Modulation ± 5%
Injection (15 kHz) ± 0.2 kHz
Frequency response:
Bandpass Filter In
Flat ± 0.4 dB
De-emphasized ± 0.5 dB
BTSC ± 1.5 dB
Bandpass Filter Out
Flat ± 0.1 dB
De-emphasized ± 0.25 dB
BTSC ± 1.0 dB
Distortion (THD+N), 10 kHz bandwidth
BPF In, de-emphasized 1.2%
BPF Out, de-emphasized 0.3%
(residual distortion 0.1%)
Signal-to-Noise, de-emphasized 65 dB
PRO Specifications (30 Hz - 3.5 kHz):
Subcarrier Peak Modulation ± 5%
Injection (3 kHz) ± 0.2 kHz
Frequency response:
BPF In, de-emphasized ± 0.5 dB
BPF Out, de-emphasized ± 0.25 dB
Distortion (THD+N), 10 kHz bandwidth
BPF In, de-emphasized 1.5%
BPF Out, de-emphasized 0.3%
(residual distortion 0.2%)
Signal-to-Noise, de-emphasized 65 dB
Dimensions 1.75"H x 16.5"D x 19"W
(1 EIA Rack Unit)
Power requirements 20 Watts, 100-240VAC, 50-60 Hz
Shipping Weight 13 lbs
© Copyright 2000 Belar Electronics Laboratory, Inc. All rights reserved.
Specifications subject to change without prior notice.
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