SIST EN 60835-3-4:2002

SIST EN 60835-3-4:2002 is the Slovenian standard for measurement methods for low noise amplifiers used in satellite earth stations. It is published by SIST and is identical to EN 60835-3-4:1995, with the IEC title Methods of measurement for equipment used in digital microwave radio transmission systems - Part 3: Measurements on satellite earth stations - Section 4: Low noise amplifier. The document tells engineers how to measure noise temperature, gain, return loss, level behaviour, and intermodulation so a low noise amplifier can be checked in a satellite earth station chain.

What does SIST EN 60835-3-4:2002 specify?

SIST EN 60835-3-4:2002 specifies measurement methods for low noise amplifiers used in satellite earth stations. It is a measurement document, so it focuses on how to test the amplifier rather than on product design requirements.

The document is organized into a short front matter, an introduction, and nine clauses covering the scope, references, and the main measurement topics.

What are the key requirements of SIST EN 60835-3-4:2002?

SIST EN 60835-3-4:2002 sets out how to measure the main performance characteristics of a low noise amplifier, and it repeatedly points back to the methods in IEC 835-1-2 and IEC 835-1-3. In practice, this means the user needs a defined test setup, known signal levels, and a clear way to compare measured behaviour against the amplifier’s intended operating range.

Measurement conditions from the introduction

When a low noise amplifier is measured as part of a sub-system, the input and output ports of the amplifier should be defined, and associated networks such as r.f. filters, switches, or directional couplers should be specified. The test signal must be low enough to avoid compression or damage, and amplifier stability should be checked during all measurements. In practice, this prevents a setup problem from being mistaken for amplifier performance.

Noise temperature and gain

Clause 3 says to measure noise temperature as described in IEC 835-1-2, while taking the noise contribution of associated sub-systems into account. Clause 4 says to measure gain within the operating level range and to measure gain stability over time. This matters because the amplifier must be tested in a way that reflects the real system and shows whether gain drifts during use.

Frequency and level behaviour

Clause 5 covers amplitude and group delay/frequency characteristics within specified frequency limits and at a test-signal level within the operating range. Clause 6 covers input/output level characteristics by varying input level and observing the output curve, which lets the user evaluate gain compression and verify the linear operating range. In practice, these measurements show where the amplifier remains predictable and where it starts to depart from linear behaviour.

Return loss, interference and intermodulation

Clause 7 refers to the IEC 835-1-2 method for input and output return loss. Clause 8 checks how out-of-band signals affect gain compression and noise temperature by applying a specified interfering signal through a directional coupler and isolation device. Clause 9 covers intermodulation products, and for low-level measurements the document allows the noise level to be reduced by terminating the direct arm of the directional coupler with a cold load. These tests matter when the amplifier must operate cleanly in a crowded satellite signal environment.

What terms does SIST EN 60835-3-4:2002 define?

• Noise temperature - A measure used here to assess the amplifier’s own noise contribution, including any associated sub-systems during the measurement.
• Gain stability - The deviation of actual gain from the nominal value at a specified frequency over a specified time interval.
• Short-term stability - Gain stability over a time scale of about 1 minute.
• Long-term stability - Gain stability over a time scale of about 1 day.
• Gain compression - The reduction in gain that can be evaluated from the input/output level curve when input level rises.
• Return loss - The input or output matching characteristic measured by the referenced basic-characteristics method.
• Intermodulation products - Unwanted products measured to assess how the amplifier behaves when more than one signal or distortion mechanism is present.

Who uses SIST EN 60835-3-4:2002?

SIST EN 60835-3-4:2002 is used by manufacturers of low noise amplifiers, test laboratories, satellite earth station operators, and engineers responsible for system integration and acceptance testing. Quality managers and buyers use it to specify which measurements should be demonstrated before equipment is accepted into a satellite earth station installation. It is relevant to the radio relay and fixed satellite communications systems field.

Which standards are used with SIST EN 60835-3-4:2002?

• IEC 835-1-2: 1992, Methods of measurement for equipment used in digital microwave radio transmission systems - Part 1: Measurements common to terrestrial radio-relay systems and satellite earth stations - Section 2: Basic characteristics - provides the basic measurement methods used for noise temperature, gain, return loss, and intermodulation references.
• IEC 835-1-3: 1992, Methods of measurement for equipment used in digital microwave radio transmission systems - Part 1: Measurements common to terrestrial radio-relay systems and satellite earth stations - Section 3: Transmission characteristics - provides the referenced methods for amplitude and group delay/frequency characteristics and for gain compression measurement.

What does the SIST EN 60835-3-4:2002 document contain?

SIST EN 60835-3-4:2002 contains a foreword, an introduction, and nine clauses that structure the measurement methods for low noise amplifiers. The introduction explains how to define ports, set safe test levels, and verify stability during measurement. The clauses then cover noise temperature, gain, gain stability, frequency response, level characteristics, return loss, out-of-band signal effects, and intermodulation products.

The document also points to the test arrangements and methods in IEC 835-1-2 and IEC 835-1-3, so users can apply consistent measurement practice across related equipment.