Overview
IEC TR 60728-3-2:2016 defines a standardized method of measurement of 5th order non-linearity for active electronic equipment in cable networks that carry only digitally modulated television signals, sound signals and interactive services. The technical report describes a five‑carrier test technique mainly aimed at MATV (Master Antenna TV) installations but also applicable to broadband amplifiers and channel‑selective amplifiers used across cable networks.
Key topics and technical requirements
- Measurement scope: Measurement of 5th order intermodulation (IM5) and related lower‑order products (3rd and 2nd order) for equipment handling digitally modulated services.
- Five‑carrier method: Configures five equally spaced carriers and identifies IM products produced by 5th order non‑linearity. (Figures and tables in the report illustrate carrier layout and IM locations.)
- Test setup and equipment: Lists required test instruments, connection diagrams and configuration for reproducible measurements (see Figure 1).
- Measurement procedures: Stepwise procedures for measuring 3rd, 5th and 2nd order intermodulation products and how to present results.
- Performance metrics: Guidance on presenting results and estimating the maximum usable output level when many channels are present.
- Frequency planning: Annexes provide example measurement carrier frequencies and IM allocations for channel spacings of 6 MHz, 7 MHz and 8 MHz across VHF and UHF bands (wide‑band and narrow‑band equipment).
- Declared characteristics: Specifies which equipment characteristics should be published to allow comparison and compliance assessment.
Applications and who uses it
This technical report is practical for:
- Manufacturers of MATV amplifiers, broadband and channel‑selective amplifiers - to validate IM performance during design and production.
- Test laboratories and certification bodies - for reproducible, standardized intermodulation testing and reporting.
- System integrators and MATV installers - to assess headend and amplifier suitability for digitally modulated services and to estimate usable output levels.
- Network operators - to ensure signal integrity and minimize intermodulation distortion in multi‑channel deployments.
Practical benefits include improved signal quality, comparable test results across vendors, and guidance for frequency/channel planning to mitigate intermodulation issues.
Related standards
- Part of the IEC 60728 series on cable networks for television, sound and interactive services. Users should consult other parts of IEC 60728 for complementary measurement methods and application-level requirements.