Downlink Equipment

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Enterprise Control System

Digital Downlink High Definition

Enterprise Control Systems Ltd (ECS) has extensive experience of both rotary and fixed-wing downlink installations. ECS is proud to have designed and proven a Coded Orthogonal Frequency Division Multiplexing (COFDM) High Definition (HD) system compliant with UK Home Office specifications MG42C, DVB-T, MPEG-2 and H.264. ECS is the only company able to offer HD video downlink transmission using Quadrature Phase Shift Keying (QPSK) modulation thus achieving a resilient link with superior range.

Digital Downlink High Definition
  • General Description
  • Technical Data

General Description

A single COFDM HD downlink system is capable of transmitting both HD and Standard Definition (SD) video. 1 HD channel, 1 HD and 1 SD channel or, 2 SD channels may be transmitted simultaneously depending on compression rate and link distance. The 3G-HDI inputs are available in accordance with the latest air camera system standards.
The COFDM HD downlink system includes a Video Encoder and Modulator (VEM), a Video Linear Transmitter (VLT) and an Encryption Control Unit (ECU). Antennas and filters are designed and provided on a system-specific basis. The VEM encodes and modulates video, audio, serial data and Global Positioning System (GPS) information into a single COFDM signal on an MPEG-2 Transport Stream. GPS may be input directly to the VEM or sourced from an ARINC429 airframe bus. The VLT has automatic gain control and does not have to be paired with a specific VEM. The ECU is Night Vision Goggle (NVG)-compatible; The ECU is used to select video source, encryption key, channel and transmitter power on/off.
An array of receive equipment compatible with the COFDM HD Downlink System is available; this, together with bespoke antenna systems and network interfacing options allows ECS to provide its customer with a complete air-to-ground solution.

Technical Data

Video Encoder & Modulator (VEM)
HDTV Video Channel: Single Video Input or Switched Single Input from three Inputs
Interface: SDI Standards SMPTE-292M, -296M, -274M, -424M (up to 3Gbps). BNC 75 Ω
Compression: AVC / H.264 / MPEG 4 Part 10.
Resolution: 1920x1080i (23.98,24,25,29.97,30 fps), 1920x1080p (25,29.97,30,50,59.94,60 fps), 1280x720p (50,59.94,60 fps)
SDTV Video Channels: Dual (Y/C and CVBS) Video Input. Single Video Input or Switched Single Input from three Inputs (SD-SDI)
Interface: SDI Standards SMPTE-259M. BNC 75 Ω, CVBS and Y/C. 2xBNC 75 Ω Compression: H.262 / MPEG 2 Part 2 Resolution: 720x576i (25 fps) PAL, 720x480i (29.97 fps) NTSC
Audio, Data & GPS: 2 Audio MPEG-1 L2 Channels. 2 Data Channels. 1 GPS (ARINC429 / NMEA0183 Serial / GPS RF)
Modulation Technique: Coded Orthogonal Frequency Division Multiplexing
Carriers: 2k in 8 MHz bandwidth
Audio and Serial Data Rate: Up to 256 kbps audio stereo pair. Up to 115 kbps data
Encryption: Substitution Cipher or, AES 256-bit (Export licence approval required)
Forward Error Correction: Reed-Solomon, Viterbi inter-leaving, outer-leaving and convolutional encoding
Power: 1.5 A. 28 VDC max
Size & Weight: 312 x 177 x 69 mm. 2.2 kg approx 
Video Linear Transmitter (VLT)
Output RF Power: 39.5 dBm +/- 2dB channel pwr for 1.4-5.3 GHz bands 37.0 dBm +/- 2dB channel pwr for 6.4 GHz band
Automatic Gain Control (AGC)
Frequency Bandwidth: 10% max proportional bandwidth
Power: 6.0 A typ for VLT15-10-6-D1.4. Up to 12 A for VLT15-10-6-D5.3. 28 VDC
Size & Weight: 269 x 122 x 137 mm. 5.5 kg 
Encryption Control Unit (ECU)
Display & Controls: Graphical LCD, NVG-compatible filters
Functions: Video input selection, channel selection, transmitter on/off, encryption key, fault alarm monitoring.
control, encryption key and transmit mode selection
Power: 28 VDC powered from VEM
Size & Weight: 57.15 x 146.05 mm (2.25 x 5.75’’ Dzus fittings). 300 g