Image Transmission Module Board PCBA

H.265/HEVC 4K Video Encoder — <120 ms Glass-to-Glass, OFDM — DO-160 / IPC-6012 Class 3

Product Overview

The Image Transmission Module Board from Superb Automation is a compact, high-efficiency PCBA that encodes, packetizes, and transmits digital video from a UAV-mounted camera to a ground receiver with minimal latency. Built around an Ambarella H22 or HiSilicon Hi3519A video processor, the board accepts raw video input via MIPI CSI-2 or HDMI and performs H.265/HEVC encoding at up to 4K resolution with bitrates configurable from 2 to 50 Mbps. The encoded stream is then packetized and transmitted through an integrated OFDM baseband modem, providing robust video links even in multipath-rich environments such as urban areas and forests. Total glass-to-glass latency — from photon hitting the camera sensor to pixel appearing on the ground display — is under 120 milliseconds, making the system suitable for real-time piloting. The board meets IPC-6012 Class 3 fabrication standards.

The 8-layer PCB features carefully isolated analog and digital domains, with the sensitive MIPI CSI-2 differential lanes routed as 100 Ω impedance-controlled pairs with intrapair skew held below 5 ps through precision length matching. A dedicated LPDDR4 memory interface running at 3200 MT/s provides the bandwidth needed for 4K video frame buffering. The board's power distribution network employs over 40 decoupling capacitors in a multi-stage PI-filter topology, ensuring clean, stable power delivery to the noise-sensitive PLLs within the video processor. An onboard microSD card slot provides local recording capability, simultaneously storing video while streaming it to the ground station, enabling post-flight review even if the RF link experiences momentary interruptions. DO-160 qualification ensures reliable operation across the UAV's environmental envelope.

Key Specifications

High-Speed PCB Design

The 8-layer stack-up dedicates two layers to the MIPI D-PHY interfaces, with all differential pairs length-matched to within 5 ps intrapair skew. The LPDDR4 interface running at 3200 MT/s requires byte-lane matching to within 10 mils and address/command matching to within 25 mils. Power integrity is maintained through a multi-stage PI-filter decoupling network with target impedance below 10 mΩ from DC to 100 MHz. The analog video input section employs a separate ground plane to prevent digital switching noise from coupling into the sensitive video PLLs. All critical traces are verified through post-layout simulation for signal integrity at full data rate.

Test Strategy

Each assembled board is tested with standardized video test sequences (color bars, resolution charts, motion sequences) to validate encoding quality across all bitrate and resolution configurations. Glass-to-glass latency is measured using a high-speed camera that simultaneously captures the test scene and the ground display. RF output power and EVM (error vector magnitude) are measured with a vector signal analyzer across the OFDM subcarriers. The microSD recording function is verified with write/read speed testing at maximum bitrate for 1-hour continuous recording endurance.

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