Description
The Model D9482 QPSK Modulator is an integral component of Scientific-Atlanta’s Digital Headend product line. This device works in conjunction with digital set-tops, including Scientific-Atlanta’s Explorer® family of set-tops, and the QPSK Demodulator to provide a forward signaling and reverse path communications for interactive video and data systems over a conventional two-way CATV plant.
Features
• Interfaces with up to eight reverse-path demodulators through ATM25 interfaces
• Contains interleaving and Reed-Solomon FEC for improved performance
• Implements DAVIC MAC control algorithm
• Provides 10/100Base-T Ethernet interface for all application data plus remote provisioning, control, status monitoring, and alarms
Specifications
Input 10/100 Base-T Ethernet
RF Specifications
Frequency Range (center frequency) 54 MHz to 550 MHz
Minimum Tuning Step Size 250 kHz
RF Output Power Level +50 dBmV to +60 dBmV (minimum range)
RF Output Impedance 75 O
RF Output Return Loss = 12 dB (45 MHz to 550 MHz)
Inband Spurious Outputs (50 MHz to 550MHz) < -57 dBc
Noise Floor (out-of-band) < -126 dBc/Hz > 25 MHz from center frequency
Output Power level with Carrier Squelched < 0 dBmV
Output Frequency Error (over temperature) < ±10 ppM
RF Test Point Level RF Output Power - 20 dB (±2 dB)
Modulation Specifications
Modulation Type Quadrature Phase Shift Keying
Error Correction Reed-Solomon t = 1
Carrier Suppression > 30 dB
Data Rate 1.544 Mbps
Data Shaping Filter Square Root Raised Cosine; alpha = 0.30
Spectral Mask Offset from Center (MHz) Response (dB)
0.5018 < -21
0.772 < -40
Error Vector Magnitude = 3.0%
Electrical Specifications
Voltage (2 options) -42 V dc to -56.7 V dc (option 1)
85 V ac to 264 V ac (option 2)
Power < 65 W
QPSK Modulator D948...
