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Applications:
- Electronic News Gathering (ENG)
- Sports
- Point of View
- Studio Wireless Links
- Helicopter links
- UAV/UGV Applications
- Mobile and Portable AV Applications
Key System Features:
- Robust Link Performance with C-OFDM
- Optional Diversity Maximal- Ratio Pre- Detect Combining
- SDI, Component & S-Video Interfaces
- 4:2:2 and 4:2:0
- 49 MHz to 6 GHz (In-Bands) with External Down-Converter
- Low System Latency (80 mS)
- Built-in MPEG-2 Decoder audio (Mic or Line level)
Cobham Surveillance (GMS Products) Broadcast version of the Messenger Digital Link (MDL) includes the Broadcast version of both the Messenger Digital Transmitter (MDT), the Messenger Digital Receiver (MDR), and one or two external Down-Converters. The Broadcast version of the MDL provides professional Audio/Video (A/V) interfaces and processing. All versions of the MDL use a robust digital modulation system known as Coded Orthogonal Frequency Division Multiplexed (COFDM) that provides frequency diversity and powerful Forward Error Correction (FEC) algorithms.
The Broadcast version of the Messenger Digital Receiver (MDR) includes an option for Spatial Maximal-Ratio Pre-Detect Diversity Combining to combat short delay spread multipath reflections found in indoor environments. The MDL provides a robust wireless link that is effective against the multipath interference experienced by analog systems, and provides crisp, clear pictures in the most difficult of terrains.
The MDRs versatile housing can sit on a desk top, be installed in a suitcase for portable applications or by adding the rack-mount option can be mounted in a 19-inch instrumentation rack. Control and status monitoring can be accomplished via the Front Control Panel, a Remote Control Unit (RCU) or via an external IBM PC and Cobham Surveillance (GMS Products) MS Windows application control software.
Critical performance parameters like Signal Strength, Signal To Noise Ratio (SNR), Modulation Error Ratio (MER) and Pre and Post FEC Bit Error Rate (BER) are provided. For frequencies > 861 MHz, external down-converters (sold separately) are used. These down-converters can be remotely mounted at the antenna to optimize system performance. DC power, control, and the IF signal all exist on a single coax cable.
The MDR receives and demodulates the DVB-T signal and decodes the MPEG-2 transport stream to recover video, optional audio (single or dual), and low-rate RS-232 data. This stream can be encrypted with either a simple fixed key scrambling system or AES to provide protection in sensitive applications. The recovered A/V data is decompressed and converted back to analog signals. The MPEG-2 supports 4:2:2 or 4:2:0 chroma sampling, 422P@ML, MP@ML and SD@ML profiles and maintains the original signal’s video fidelity. The Broadcast version of the MDR outputs ASI, SDI, Component or S-video signal, Composite video signal, analog stereo audio.
One of the biggest problems encountered in the transition from an analog to a digital A/V platform has been the inherent digital coding delays that in some digital systems are 400ms or more. The MDT/MDR Broadcast version combination employs a specially designed ‘low delay’ coding technology, which provides an end-to-end latency of approximately 80ms without the introduction of any further MPEG encoding artifacts. This ensures that the picture you see is what is happening now - crucial for applications such as sports coverage, surveillance, and law enforcement, where personnel are reacting to real-time events.