FprEN 3475-812

Overview

FprEN 3475-812 is a draft European standard developed by CEN, addressing test methods for measuring return loss and voltage standing wave ratio (VSWR) in coaxial cables intended for aerospace electrical applications. Measuring return loss and VSWR is essential to ensure reliable signal transmission in aircraft electrical systems, as these parameters directly reflect how efficiently the cable transmits signals and manages impedance mismatches.

This standard forms part of the comprehensive EN 3475 testing series and is intended to be used in conjunction with other key standards such as EN 3475-100 and EN 50289-1-11:2016. Proper understanding and implementation of return loss and VSWR measurements are critical for maintaining high-performance communication and control systems in aerospace environments.

Key Topics

• Return Loss Measurement: The standard outlines procedures to quantify the amount of signal reflection caused by impedance mismatches or manufacturing variations in coaxial cables.
• Voltage Standing Wave Ratio (VSWR): Specifies methods to calculate VSWR from the measured return loss. VSWR is a critical parameter that affects signal integrity in high-frequency applications.
• Test Specimen Preparation: Details requirements for specimen length (typically 10m unless otherwise specified), connector installation, and verification of connection quality.
• Measurement Conditions: Stipulates the use of standardized termination, referencing the system's nominal impedance, and employs correction procedures for accurate high-frequency measurement.
• Acceptance Criteria: Ensures that measured return loss and/or VSWR values do not exceed the limits defined in the relevant product standard.

Applications

• Aircraft Electrical Systems: Ensures that coaxial cables used in aircraft meet stringent return loss and VSWR performance criteria, supporting reliable data and signal transmission in avionics and communication systems.
• Aerospace Cable Manufacturing: Provides a recognized method for manufacturers to validate the quality and performance of their products according to European aerospace requirements.
• Quality Control and Compliance: Used by laboratories and quality assurance teams to evaluate cable performance, identify manufacturing defects, and verify compliance with industry standards.
• Research and Development: Supports engineers in developing new cable types or installation practices by providing standardized measurement techniques for return loss and VSWR.
• Maintenance and Troubleshooting: Helps maintenance teams diagnose and resolve issues related to signal degradation by identifying impedance mismatches or cable faults.

Related Standards

• EN 3475-100: Aerospace series - Cables, electrical, aircraft use - Test methods - Part 100: General, providing overall guidance on test procedures for aerospace cables.
• EN 50289-1-11:2016: Communication cables - Specifications for test methods - Part 1-11: Electrical test methods - Characteristic impedance, input impedance, return loss, offering detailed procedures and correction techniques crucial for precision measurements.
• EN 3475-805: Aerospace series – Cables, electrical, aircraft use – Test methods – Part 805: Characteristic impedance, relevant for verifying the nominal impedance of the cable under test.

FprEN 3475-812 is a critical document for organizations involved in manufacturing, testing, and using coaxial cables within the aerospace industry. By adhering to this standard, stakeholders ensure that aircraft cables achieve the required levels of signal transmission quality, safety, and reliability.