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

SOFTWARE
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)

MEASUREMENTS

• Total peak deviation in percent
• SAP Injection in kHz
• Pro Injection in kHz
• SAP audio output level in dB
• PRO audio output level in dB

SETTABLE PARAMETERS

• SAP Peak Mod flasher level
• SAP Mute (On/Auto/Off)
• SAP Mute Level (in kHz)
• SAP Bandpass Filter
• SAP Detector Bandwidth
• SAP Response
• SAP Calibrator (5 functions)
• PRO Peak Mod flasher level
• PRO Mute (On/Auto/Off)
• PRO Mute Level (in kHz)
• PRO Bandpass Filter
• PRO Calibrator (3 functions)
• Hold Time
• Time Mode
• Infinite Hold

Additions to the TVM-250:

MP-250

Belar has a number of analog remote meter panels for use with Belar TV monitors. The MP-250 Analog Meter Panel is designed for use with the TVM-250 TV SAP/PRO Modulation Monitor. It features 2 large back-lit meters that display SAP modulation and PRO modulation. Four LED's mirror the LED's on the TVM-250 and show SAP Carrier, SAP Peak, PRO Carrier, and PRO Peak.