SIST EN 60835-2-4:2002/A1:2002

SIST EN 60835-2-4:2002/A1:2002 is a SIST adoption of Amendment 1 to IEC 60835-2-4 for methods of measurement on digital microwave radio transmission equipment. It specifies a selective fading signature measurement for terrestrial radio-relay transmitter/receiver chains, including the modulator/demodulator, for engineers who need to compare receiver behaviour under multipath fading and document acceptance or type-test results.

What does SIST EN 60835-2-4:2002/A1:2002 specify?

SIST EN 60835-2-4:2002/A1:2002 adds one measurement topic to the terrestrial radio-relay section of the digital microwave measurement series: selective fading signature. In practice, it tells test engineers how to simulate multipath fading in the receiver path and how to record the receiver response at a specified BER.

The added material is organized as Clause 5.3 with four subclauses:

• 5.3.1 General considerations
• 5.3.2 Method of measurement
• 5.3.3 Presentation of results
• 5.3.4 Details to be specified

It also adds Figures 5 to 7, which support the simulator arrangement, its frequency characteristic, and an example signature plot.

What are the key requirements of SIST EN 60835-2-4:2002/A1:2002?

SIST EN 60835-2-4:2002/A1:2002 focuses on how to measure a receiver’s sensitivity to selective fading caused by multipath propagation. The practical aim is to produce repeatable results that can be compared between systems and used to estimate outage behaviour in the field.

Main points in the method

• The standard uses a two-ray fading simulator in the i.f. or r.f. path of the receiver. This matters because it creates a controlled fading notch instead of relying on uncontrolled field conditions.
• The simulator splits the signal into a direct path and a delayed path, then recombines them. The notch depth and notch frequency displacement are adjustable, so the test can mimic different fading severities and channel positions.
• The delay is selected so the notch spacing is much wider than the channel bandwidth. In practice, that lets the test produce one main notch within the channel band, which is the usual selective fading case.
• Measurement follows the same basic arrangement as the BER test setup, with the simulator inserted at the receiver input. The receiver is first set to a nominal input level with a flat response, so the signature measurement is not dominated by thermal noise.
• Two measurement methods are allowed. Method 1 fixes the notch offset frequency and increases notch depth until the threshold BER is reached; Method 2 fixes notch depth and moves the notch frequency until the threshold BER is reached. Method 2 is better for large offsets, while Method 1 is better near the band centre.
• Measurements are made for both minimum phase and non-minimum phase conditions, and the test should be run by increasing and decreasing notch settings to detect hysteresis. This helps reveal whether the receiver response depends on test direction.
• Results are presented graphically as notch depth in decibels versus notch frequency displacement from the band centre. That gives a clear signature curve that can be compared across equipment.
• The detailed equipment specification should state items such as receiver input level, bit rate, pseudo random sequence length, BER measurement time, threshold BER, simulator delay time, notch range or notch depth, and whether the test is minimum phase or non-minimum phase. This ensures the same test can be repeated and interpreted consistently.

What terms does SIST EN 60835-2-4:2002/A1:2002 use?

• Selective fading signature - The notch-shaped response recorded when the receiver is tested with a simulated multipath fade across the channel.
• Two-ray fading simulator - A test arrangement that combines a direct signal and a delayed signal to create a controlled fading notch.
• Bit error rate (BER) - The error rate used as the threshold for deciding when the fading condition has reached the specified limit.
• Minimum phase - The condition where the direct-path signal has the higher amplitude.
• Non-minimum phase - The condition where the delayed-path signal has the higher amplitude.
• Notch depth - The depth of the simulated fade, adjusted in the test to reach the threshold BER.
• Notch frequency displacement - The offset of the fade notch from the channel band centre.
• Pseudo random sequence - The digital test pattern used during BER measurement.

Who uses SIST EN 60835-2-4:2002/A1:2002?

SIST EN 60835-2-4:2002/A1:2002 is used by manufacturers, test laboratories, and system engineers working on digital microwave radio transmission systems. It is especially relevant for acceptance and type testing of terrestrial radio-relay equipment.

It also supports people comparing adaptive equalizers and assessing how a receiver behaves under multipath fading. Quality teams and buyers can use it to understand what should be measured, what results should be recorded, and which conditions must be stated in the equipment specification.

What changed in SIST EN 60835-2-4:2002/A1:2002 from the previous edition?

SIST EN 60835-2-4:2002/A1:2002 adds Clause 5.3 on selective fading signature to the transmitter/receiver measurement section.

It introduces:

• the two-ray fading simulator concept
• two alternative measurement methods
• guidance for presenting signature results
• a list of items to include in the detailed equipment specification
• Figures 5 to 7 for the simulator arrangement, its frequency characteristic, and an example signature

Which standards are used with SIST EN 60835-2-4:2002/A1:2002?

The amendment refers to IEC 60835-2-8 for the BER measurement arrangement used with the selective fading test. In practice, that companion part supplies the broader BER test setup, while this amendment adds the fading simulator and the signature method.

What does the SIST EN 60835-2-4:2002/A1:2002 document contain?

SIST EN 60835-2-4:2002/A1:2002 contains the new text for Clause 5.3, including the method, result presentation, and specification items. It also contains the formula for the simulator transfer function, which is used to explain how the notch behaves.

Figures 5 to 7 show the functional arrangement of the two-ray fading simulator, its wideband frequency characteristic, and an example of minimum phase and non-minimum phase signature curves. These parts support lab setup, test execution, and result recording without requiring the reader to derive the method from the formula alone.