Wireless transmitters have dramatically increased in number over the last decade. The Internet of Things (IoT) has created demand for low-cost chipsets, which are based on technologies like Bluetooth, ZigBee, and Wi-Fi. Such chipsets utilize unlicensed radio spectrum like the 2.4-GHz band, which is extremely popular for low-cost, license-free applications. Unfortunately, problems are encountered in terms of establishing radio links and maintaining communications, resulting in the need for troubleshooting. In the tutorial, "Trouble-shooting Radio Links in Unlicensed Frequency Bands," Tektronix explains why a real-time spectrum analyzer (RTSA) is an important tool for today’s troubleshooting requirements.
The tutorial begins by discussing the traditional spectrum analyzer, as it is the primary tool for performing spectrum-based measurements. A simplified block diagram of a traditional swept-tuned spectrum analyzer is presented. These spectrum analyzers perform swept measurements, meaning the displayed measurements are disjointed in time. Therefore, the spectral information may not be accurately represented, especially in the case of time division multiple access (TDMA) signals.
A block diagram of a basic RTSA is then presented. An RTSA possesses capabilities that traditional swept-tuned spectrum analyzers do not have. For any span within the maximum real-time span, an RTSA can continuously capture spectrum information instead of having to perform swept measurements. RTSAs are also not limited to a single display at one time: Spectrum, spectrogram, and modulation information can be simultaneously analyzed. And because this data is from a continuous acquisition, the information is time-correlated.
Devices that utilize license-exempt frequency bands must withstand the effects of multiple transceivers sharing the same spectrum. Regulatory requirements almost always require that devices operating in unlicensed frequency bands cause no interference, as well as accept any interference that is present. The tutorial explains in greater detail how the capability of an RTSA to continuously capture spectrum information makes it well suited to quantify the effects of interference. The document concludes by presenting a digital phosphor spectrum display and spectrogram from an RTSA.
Tektronix Inc., 14150 SW Karl Braun Dr., Beaverton, OR 97077; 800-833-9200
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