Inter-Satellite Links

The core of Starlink Cable is PoE (Power over Ethernet) technology, which can simultaneously transmit data and power in one cable, achieving "one wire for two uses". It is a key link connecting the user terminal (satellite antenna/Dishy) with the router/power supply. The following comprehensively dissects its operational mechanism from technical principles, physical structure, working processes to special designs.
I. Core Technology: The Working Foundation of PoE
Starlink cables are essentially PoE cables that comply with the IEEE 802.3 standard, consisting of two core components working together:
Component role function
PSE (Power Sourcing Equipment), the power supply end Starlink power adapter/router, is responsible for detection, classification, and power supply management, and outputs 48V DC power
PD (Powered Device, receiving device) power receiving end Starlink satellite antenna, with built-in PoE receiving chip, converts 48V to its own working voltage (usually 12-24V)
Key working steps of PoE
Detection stage: PSE checks whether the other end of the cable is a PD device that meets the standards (to prevent power supply to non-poe devices)
Grading stage: Negotiate the power required by the PD (about 10-30W for Starlink antennas, depending on the model)
Power supply stage: Stably provide 48V DC power and simultaneously transmit data
Power-off stage: When the equipment is disconnected, the power supply will automatically stop to ensure safety
Ii. Physical Structure and Transmission Mechanism
1. Internal structure of the cable
The standard starlink cable is an 8-core twisted pair (Cat5e/Cat6/Cat6a grade), and the following design is adopted to achieve parallel transmission of power and data:
Line pair function transmission mode
1/2 and 3/6 pairs of data transmission differential signals, supporting 10/100/1000Mbps rates, full-duplex communication
The 4/5 and 7/8 pairs are used for power transmission. The idle pairs supply power, with 4/5 being the positive pole (+) and 7/8 being the negative pole (-), and the DC voltage is 48V
The anti-interference multi-layer shielding (aluminum foil + woven mesh) reduces the interference from rain, snow and strong electromagnetic environments, ensuring signal stability
Note: The new generation of starlinks (such as Gen3) uses Cat6a/super Category 6 cables, supporting higher power (PoE++/802.3bt, up to 90W) and a rate of 10Gbps
2. The Secret of Parallel power and Data
Frequency isolation: The electricity is direct current (0Hz), and the data is high-frequency differential signals (hundred-megabit/gigabit level), and the two do not interfere with each other
Safety voltage: 48V is classified as a very low safety voltage (SELV), posing no risk of electric shock to the human body and meeting the power supply requirements of the equipment
Power management: The PSE monitors the current in real time. When the PD is disconnected or abnormal, it automatically cuts off the power supply to prevent short circuits and overloads
Iii. Complete Workflow (User Internet Access Link)
When users access the Internet via Starlink, the transmission paths of data and power are as follows:
plaintext
Mains power (110/220V AC) → Starlink power adapter (PSE) → Starlink cable → Satellite antenna (PD)
left
Bidirectional data transmission and unidirectional power supply (48V DC)
left
User equipment (mobile phone/computer) ←→ Router ←→ Starlink cable ←→ Satellite antenna ←→ Starlink satellite
Detailed step-by-step breakdown
Power flow: The power adapter converts the mains power to 48V DC → through the idle pairs of the starlink cable (4/5,7/8) → the built-in PD chip of the antenna reduces the voltage → supplies power to the phased array radar, processor, and RF module of the antenna
Data stream
Uplink: User data → Router → Starlink cable data pair (1/2,3/6) → Antenna → Satellite → Ground station → Internet backbone network
Downlink: Internet data → Ground station → Satellite → Antenna → Starlink cable → Router → User equipment
Signal processing: The antenna receives the Ka/Ku band RF signals from the satellite → converts them into digital signals → transmits them to the router through PoE cables, completing the "space-ground link" conversion