A client requires a long-range, full HD video transmitter for a drone, operating in the L or S band, with a data rate of 8Mbps, SDI video input, and a range of 200km; LAN and HDMI inputs are unnecessary. Input only SDI.
After comprehensive analysis of customer needs, our one-way transmission links and two-way transmission links can basically meet customer needs. However, some optional parameters require adjustment.
If the customer agrees to a one-way transmission link, we recommend the Vcan1726 basic model adjustment, using a 20W amplifier to meet the customer’s 200km transmission distance requirement, Vcan1726-10W and replacing the HDMI video encoding board with an SDI video encoding board.
If the customer agrees to a two-way transmission link, and he just can’t agree the RJ45 Ethernet video input, we can use an SDI video input to network port output video adapter board to meet the customer’s SDI video input needs, and using a two-way wireless link has another benefit of being able to control the drone. The customer does not need an additional data transmission link, and over 200 kilometers, a device can be added between the transmitter and the receiver to achieve signal relay and enhancement functions.
Table of Contents
Demand and Solution
Video input
Select a transmitter that supports SDI (such as 3G-SDI/HD-SDI) interface to ensure compatibility. We have SDI video encod boarding. so video input can meets SDI input demands.
Frequency band
L band (1-2 GHz) is preferred because its low frequency characteristics are more suitable for ultra-long-distance transmission (200 kilometers), but care should be taken to avoid military or satellite frequency bands.
Two-way transmission link Vcan1933 supports 1350-1470Mhz. One-way transmission link Vcan1729-TX supports 70Mhz-4Ghz, but Vcan1729-RX supports 200Mhz~860Mhz, it has to add extra frequency down converter from 1365Mhz to 600Mhz. (LO765Mhz)
Data rate
It needs to support 8Mbps compressed encoding transmission (such as H.265/HEVC) to ensure bandwidth efficiency at 1080p image quality.
Two-way transmission link Vcan1933 supports 10Mbps or 20Mbps to choose. One-way transmission link Vcan1726 supports 0.5Mbps to 31.67Mbps （bites per second）.
Transmission distance
The client requires 200km transmission range, it needs high-power transmission (10W+ PA), low-noise reception, and a high-gain directional antenna (13~16dBi).
Vcan1933 10-Watts PA supports 200km, here is 186Km test video. It recommends use the automatically tracker with flat panel directional antenna. Vcan1726 needs to use 20-watts power amplifier to ensure the good signal reach. We recommends to use one big and long fiberglass omnidirectional antenna and one yagi directional antenna.
Recommended technical solutions
Modulation technology
COFDM (multi-carrier modulation) Vcan1729 or OFDM Vcan1933 is used, which has strong anti-multipath interference capability and is suitable for complex environments.
Compression coding
H.265/HEVC must be supported to achieve high-definition image quality at 8Mbps.
Antenna solution:
The drone end uses a lightweight omnidirectional antenna, and the ground station uses a high-gain tracking antenna (such as a phased array) to improve link stability. More antenna, please check here.
Key challenges and considerations
Regulatory compliance
L/S bands may require a radio license (such as SRRC certification in China) to avoid frequency band conflicts.
Power consumption and weight
High-power transmitters need to match the drone power system, and the antenna size needs to be lightweight.
Environmental adaptability
Anti-interference capabilities (such as Doppler effect and weather attenuation) need to be tested, and redundant links may be required.
The curvature of the earth
The 200km transmission distance mentioned here requires that the transmission distance is within the line of sight, that is, there is no obstruction between the transmitter and the receiver. Considering that the earth is round, if the straight-line transmission distance still needs to be maintained, the flight altitude of the drone must be high enough. We can also consider using an intermediate relay to overcome ground obstructions and enhance the wireless transmission signal.
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