Troubleshooting and practical application of Advantest U3771/3772 microwave spectrum analyzer

Advanced measurement functions and practical fault location

In daily maintenance and troubleshooting, U3771/3772 provides rich standard measurement functions. This includes:

OBW measurement: Automatically calculates the bandwidth and center frequency for a specified power ratio (10% to 99.8%), which is a powerful tool for evaluating the compliance of transmitter spectrum templates.

Harmonic measurement: Simply input the fundamental frequency or place a marker to automatically measure up to 10 harmonic components, which is very suitable for stray response testing of wireless transmitters.

Frequency counter: For the millimeter wave frequency band, the instrument can be used as a frequency counter by placing marker points on the signal, with a resolution range of 1 Hz to 1 kHz.

Channel power to adjacent channel leakage ratio (ACLR): used to evaluate the degree of interference of the transmitter on adjacent channels.

Practical cable fault location:

In the maintenance of the base station antenna feeder system, damage or water ingress of coaxial cables can lead to severe deterioration of standing wave ratio. With the optional OPT.76 (3 GHz) or OPT.77 (6 GHz) tracking generator, as well as sample software on an external PC, U3771/3772 can achieve distance measurement of cable fault points. By emitting a sweep signal to the cable and analyzing the reflected wave, engineers can accurately measure the distance of the open or short circuit fault point from one end of the cable. In addition, by combining SWR bridge, the return loss characteristics of antennas or filters can be directly measured, greatly improving the troubleshooting efficiency of outdoor antenna feeding systems.

Guidelines for Option Configuration and System Integration

In order to meet the depth requirements of different application scenarios, U3771/3772 provides flexible option upgrade paths:

OPT.10 (Dual Channel Input): Add an independent second RF input channel, suitable for research and advanced diagnostic scenarios that require parallel processing of multiple signals.

OPT.20 (High Stability Frequency Reference Source): Increases aging rate to ± 2 x 10 ^ -6/day, significantly improving frequency counting accuracy, suitable for long-term monitoring and high-precision frequency measurement.

OPT.28 (EMC Filter): Increase the CISPR standard's 6 dB bandwidth (200 Hz, 9 kHz, 120 kHz, 1 MHz) and equip it with a quasi peak detector, making it a powerful tool for electromagnetic compatibility prediction testing and electromagnetic interference investigation.

OPT.53-56 (Time Domain Analysis): As mentioned earlier, it provides a time dimension perspective for complex modulation signals and radar pulse analysis.

OPT.76/77 (Tracking Generator): Used for frequency response testing, filter characteristic evaluation, and cable fault location.

In terms of system integration and remote monitoring, the instrument comes standard with a 10/100BASE-T LAN interface. This means that it can not only serve as an independent on-site testing tool, but also be deployed in unmanned wireless transmission stations. Engineers can use remote control software on their personal computers to monitor signal output, adjust parameters, and even capture spectrum images in real-time from different locations (supporting PNG and BMP format storage), truly achieving unmanned automated spectrum monitoring.

Evaluate microwave oscillation circuits and modules

In the laboratory research and development environment, with the help of external PC example software, U3771/3772 can efficiently evaluate the phase noise characteristics of microwave oscillation circuits and microwave modules. The software allows users to set frequency ranges that deviate from the carrier and automatically generate phase noise curves. In addition, by setting a specific frequency band, RMS jitter can be calculated from the power spectrum. This design concept of integrating professional level measurement capabilities into portable devices enables R&D personnel to obtain laboratory level data support during prototype debugging.