Pulse Modulated PIM Measurement Instrument
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Solution Overview
Problem
Passive intermodulation (PIM) interference in wireless communication systems reduces receive sensitivity and causes call drops, especially in cellular networks with high-speed digital data communications, and existing measurement systems face challenges in efficiently detecting and locating PIM sources, particularly in low-power environments like distributed antenna systems (DAS) networks.
Innovation Solution
A measuring instrument generates test signals with two or more tones amplified to a target output power using a duty cycle, allowing for efficient PIM calculation by averaging measurements over a sweep of frequencies, with the duty cycle determined based on the target output power to maintain constant average power consumption and improve receiver sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the amplifier operates continuously at high power to improve measurement speed, then productivity increases, but the noise floor increases and receiver sensitivity deteriorates
Solution Approach 1:
The amplifier operates in periodic pulses rather than continuously. The duty cycle is adjusted based on target output power requirements, allowing the amplifier to be active only during measurement intervals and inactive during integration intervals, thereby reducing average power consumption and noise floor while maintaining measurement capability
Solution Approach 2:
Multiple measurements are taken during the active portion of the duty cycle and stored for later integration. The integration process combines these pre-collected measurements during the inactive period, improving receiver sensitivity without requiring continuous high-power operation
2Measurement precision
If the amplifier operates at high power to improve signal strength, then measurement precision improves, but power consumption increases
Solution Approach 1:
The system uses pulsed operation with adjustable duty cycles to deliver high peak power only when needed for measurement, then reduces power during integration periods. This maintains measurement precision while significantly reducing average power consumption compared to continuous operation
Solution Approach 2:
The duty cycle is dynamically adjusted based on the target output power requirements. The system can adapt between different power consumption modes while maintaining the ability to achieve required signal strength during active measurement periods
3Stability of the object's composition
If the amplifier operates continuously to maintain constant power output, then power stability improves, but noise floor increases
Solution Approach 1:
The system separates operation into distinct phases: active measurement phases with high power output and inactive integration phases with reduced power. This periodic structure maintains power stability during measurements while reducing overall noise floor through the inactive periods
Solution Approach 2:
Multiple measurements are collected during active phases and then integrated during inactive phases. This preliminary collection and subsequent integration approach maintains power stability when needed while utilizing low-power periods for signal processing
Data Source
AI summary
In an embodiment, a method for measuring passive intermodulation (PIM) associated with a device under test (DUT) includes generating a test signal using a measuring instrument and obtaining measurements of PIM for the DUT. The test signal comprises two or more tones each amplified to a target output power by a respective amplifier according to a duty cycle. Measurements are obtained by the measuring instrument during an active portion of each duty cycle over a sweep of frequencies. PIM is calculated for the DUT by averaging a plurality of measurements obtained for each frequency from the sweep of frequencies. The duty cycle is determined based on the target output power.