LAN power sensor represents new category of RF, microwave instrument
Traditional power-meter solutions typically consist of the benchtop form factor with a separate power sensor that is changeable to adapt to different applications based on frequency range or power range requirements. Over the past decade, an increasing number of portable power meters in the USB form factor have been introduced. These USB power sensors have made inroads into many major applications, including fast production testing of wireless communication chipsets or radar pulsed components in both wireless and aerospace/defense applications.
Recently, a new category of power sensors with local area network (LAN) connectivity has emerged. These power sensors have created excitement in many markets and applications, generating new applications or use cases that were not possible or convenient in the past. This article explores the benefits of the LAN power sensor in certain applications such as multichannel satellite transmitter tests and outlines two minor limitations associated with LAN-based instruments.
Why are LAN power sensors unique?
LAN power sensors operate over a long distance. LAN connectivity allows users to access the LAN power sensor from any PC on the network. The use of LAN connectivity makes it possible to place the sensor far away from the host PC and closer to the device-under-test (see figure). This can be beneficial in two ways. First, the sensor can be physically located in critical areas (such as on top of an antenna mast or radar tower), providing more accurate power measurements without needing to connect a long RF cable between the sensor and the device-under-test. Second, users are able to control the sensor from thousands of miles away, and the results can be monitored by many parties at the same time.
In a satellite uplink or downlink fault-monitoring system, personnel who monitor the satellite’s performance often are located separately from the actual antenna towers, often in different locations altogether. By using a LAN, users can control the system remotely and observe sensors that are located physically far away, allowing anyone who is on the network to connect to the sensor from any part of the world and receive nearly instant feedback. This remote monitoring and control capability can significantly reduce operational downtime, enhancing system efficiency.
Multichannel operations
LAN power sensors are ideal for multichannel power measurements. Multiple power sensors can be tied together easily over a network via LAN switches or routers. This setup is useful to offload high-performance analysis to multiple PCs to scale the processing performance. Each sensor can be configured to perform parallel or sequential measurements, log data, and stream only necessary measurement results over the network to the control center. The built-in trigger input and trigger output ports of the LAN sensors enable users to daisy-chain the power sensors (as many as they like) for acquisition timing control and synchronization with other equipment, such as a signal source or a spectrum analyzer.
Easy programming
LAN sensors are ideal for both programmers and nonprogrammers. Users with little or no programming knowledge can employ the bundled PC software to configure settings and retrieve measurement results from the power sensor. Programmers have the flexibility of using any programming software of their choice to develop their codes. The LAN sensor is programmable via SCPI, IVI-COM, IVI-C, or NI LabVIEW drivers. This programming versatility allows the sensor to be easily integrated into any current test platform.
LXI-compliant
LXI is the standard for LAN-equipped instruments, and it helps to reduce the time it takes to set up, configure, and troubleshoot a test system. The LAN power sensor is LXI-compliant and can be controlled via an Internet web browser or PC software. This simplifies the sensor’s configuration and setup. The built-in web browser makes it easy for users to configure and view the status of the LAN sensor. Simply launch the PC software to start configuring the sensor’s measurement settings and monitoring the results in real time on a soft front panel.
Simplify test setup and save rack space
A LAN power sensor can be connected to the LAN port or router directly without occupying any space on the test rack. It is a standalone device that does not require PC software to process measurements. All measurement acquisitions, data conversion, and analysis are completed in the onboard electronics and signal-processing circuits, offering fast and accurate power measurements. The PC is only required as a user interface and to display the results.
Potential drawbacks
Despite the benefits, users also should be aware of the limitations of LAN-based instruments:
- Long latency—Latency is the time delay between the stimulation and the response. The long latency of LAN sensors when compared to USB or GPIB instruments will cause slower measurement rates, especially for applications that require a large number of simple commands or data to be transferred. But LAN (especially Gigabit Ethernet) offers high bandwidth for data-intensive applications such as transfer of high-resolution waveform data to the PC for post-processing. This is extremely useful for transferring raw sampling points of measured pulsed signals for reconstructing the pulse envelope on the PC software.
- Complex configuration—In general, setting up a LAN power sensor is simple, but it requires more steps than setting up a USB sensor. LAN needs an IP address and other network configurations, which might be subjected to the IT policy of individual companies. Some of the remote capability of the LAN instrument might be compromised due to firewalls or the company’s network security policy.
The easiest way to connect to a LAN power sensor is through the dynamic host configuration protocol (DHCP), whereby an IP address will be automatically assigned to the sensor connected to the network. However, the IP address assigned by the DHCP can change without warning during disconnection and reconnection. For instance, a system that contains two power sensors may have their IP addresses reversed due to DHCP configurations. This will result in a mix-up of measured signals and may lead to the wrong data being collected.
Users also can assign a hostname or a statically configured IP address. This will prevent the sensor from receiving a new IP address every time it is being disconnected and reconnected. Setting up a static IP address requires a few more steps and will need some instruction to do it correctly.
Conclusion
LAN-based instruments simplify the test setup and enable easy system integration with standard SCPI commands or IVI and LabVIEW drivers. LXI-compliance with a standard web browser enables long-distance remote access of the instrument from any part of the world. Multichannel measurements can be carried out with the addition of a LAN switch or router.
The Keysight U2049XA LAN/PoE (Power over Ethernet) power sensor is the first LAN power sensor with a wide dynamic range of 90 dB, and it enables accurate RF and microwave power measurements from 10 MHz to 33 GHz. The U2049XA LAN power sensor is suitable for long-distance remote monitoring when paired with a standard RJ45 LAN cable for a distance up to 100 meters. Longer distance monitoring is possible by connecting the sensor to a shared network via a PoE switch or hub. The power sensor can be controlled remotely from any part of the world with a standard web browser and Keysight BenchVue software. With its patented internal zero and calibration technology, the U2049A enables automated performance monitoring without human intervention.
About the author
Sook Hua Wong, who has been with Keysight Technologies for 16 years, currently is an industry segment manager residing in Penang, Malaysia. Previously, she was the product planner responsible for strategic planning and product portfolio development for RF/microwave power meters and sensors. Wong received her bachelor’s degree in electrical engineering from the University of Technologies Malaysia (1999) and a master’s of science degree in electronic system design engineering from the University of Science Malaysia (2003). [email protected]
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