Headend Info Sheets
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New Products
- AMCM-860S - Stereo Agile Modulator
(36KB, PDF)
- MISE
(52KB, PDF) - Complete Headend Section
(1,900KB, PDF) - Commercial Satellite Receiver
(76KB, PDF) - Commercial Digital Satellite Receiver
(112KB, PDF) - HDA
(60KB, PDF) - Broadcast Frequency Locked Modulator
(88KB, PDF) - Modulators - Agile
(160KB, PDF) - Modulators - Channelized Agile
(68KB, PDF) - Processors - Channelized and Agile
(116KB, PDF) - Demodulators - Agile Audio/Video
(68KB, PDF) - HE Series -
(18KB, PDF) - Bandpass Filters
(116KB, PDF) - Passive Combiners
(64KB, PDF) - Active Combiners
(68KB, PDF) - Channel Converters
(68KB, PDF) - Channel Elimination Filters
(60KB, PDF) - Headend Racks, Panels, and Cabinets
(520KB, PDF) - Strip Amplifiers
(84KB, PDF) - Tunable Notch Traps
(88KB, PDF) - Low Cost Headend Products
(168KB, PDF) - Video All Call System
(68KB, PDF) - IF Demodulator/Modulator
(76KB, PDF) - HAVM Agile Modulator
(96KB, PDF)
Headend Overview
Features & Benefits
- Blonder Tongue Headend Products Feature Superior Performance at Affordable Prices
- All Products Exceed FCC CATV Specifications and Typically Meet FCC Broadcast Specifications
- Commercial Quality Equipment Provides Exceptional Picture Quality
- High CNR/SNR Performance Permits Large Multi-Channel Headends, Even with Agile Units
The Headend is the heart of CATV system. It handles many functions including reception and processing of broadcast or “off-air” television signals and reception, decryption and modulation of satellite delivered programming in preparation for distribution to cable television subscribers.
The broadcast signals routed to the headend are filtered to reject any unwanted signals from adjacent off-air channels and adjusted for proper aural & visual carrier levels in. They can be fed to a signal processor or a demodulator / modulator approach can also be used.
The majority of CATV channels are delivered to the headend via satellite. In this method signals are uplinked to a communications satellite in geosynchronous orbit from an uplink facility. The satellite then retransmits the signal back to earth where it is received by dish shaped antennas which focus the signals. At the dish, an LNB (low noise block converter) amplifies the signals and delivers them to the headend via a coaxial cable. Most satellite signals are scrambled and the satellite receiver in the headend is used to decode the signals. These units may have the ability to decode or decrypt the scrambling of a particular format or type of signal built in (IRD). The satellite receiver typically converts the signal to a baseband audio & video signal. This signal is then modulated onto any desired CATV channel.
The CATV headend uses frequency division multiplexing to combine signals from broadcast TV processors, satellite fed modulators and locally originated system specific channels onto a single feed. The combining process is passive since the signals already occupy discrete frequencies and have been adjusted to the same RF carrier level by their respective processing equipment. Passive combiners simply provide multiple signal ports where different signals are connected and are combined onto a single output containing all of the input signals. A post amplifier, sometimes called a launch or distribution amplifier, then amplifies the signals and provides slope control so that the entire range of carriers can be at the correct RF level for launching to the distribution system.