Portable Analyzers Hunt For Interference

Portable Analyzers Hunt For Interference

This line of portable spectrum analyzers, when equipped with an additional interference-finding system, can detect and identify RF/microwave interference sources in the field.  

Interference can ruin the best-laid plans, especially when it blocks the intended signals in an RF/microwave communications system. But finding a source of interference can be tricky; such factors as reflections and multipath make signal detection challenging for even the most sensitive spectrum analyzers.

Fortunately, there is now the Spectrum Master™ MS2720T series of handheld spectrum analyzers from Anritsu Co., suitable not only for detecting those hard-to-find interference signals but for qualifying the performance of RF/microwave communications systems through 43 GHz. The analyzers bring a tremendous amount of operating flexibility, with both sweep and signal triggering capabilities, so that any search for signal interference can be performed as quickly and efficiently as possible.

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1. The Spectrum Master™ MS2720T series of handheld spectrum analyzers now includes models through 43 GHz with a wide choice of sweep options and resolution bandwidths.

The MS2720T analyzers (Fig. 1) are portable instruments with benchtop-instrument performance. Each analyzer links to its operator by means of an 8.4-in. touchscreen (Fig. 2), which enables users to add shortcut buttons to speed and simplify measurements and control the instrument. The analyzers can also be equipped with tracking signal generators with frequency coverage to 20 GHz, enabling them to generate signals to measure (for example) the performance of filters.

2. The MS2720T portable spectrum analyzers feature an 8.4-in. touchscreen to speed and simplify measurements.

The broadest-frequency unit, model Spectrum Master MS2720T (Fig. 3), spans 9 kHz to 43 GHz, with an improved sweep mode that allows resolution bandwidths to be set from 30 kHz to 10 MHz with minimal effect on sweep speed. There is no need to sacrifice sensitivity for the sake of faster sweep speed: The sweep speed for a 30-kHz resolution bandwidth is nearly the same as a sweep performed with a 10-MHz resolution bandwidth; the resolution bandwidth range is 1 Hz to 10 MHz.

3. The Spectrum Master MS2720T portable analyzer covers a frequency range of 9 kHz to 43 GHz with resolution bandwidths from 30 kHz to 10 MHz.

These versatile analyzers provide numerous ways to search for signals, such as using different detector modes and different sweep modes, including the Burst Detect™ function. Measurements can be performed in zero span or across a choice of frequency spans—including from 10 Hz to 9, 13, 20, 32, or 43 GHz. 

The MS2720T portable spectrum analyzer is truly an instrument that can hold its own with the best benchtop spectrum analyzers. It achieves a dynamic range of better than 106 dB, with a displayed average noise level (DANL) of -163 dBm using a 1-Hz resolution bandwidth. Its sensitivity is aided by low phase noise of -112 dBc/Hz offset 10 kHz from a 1-GHz carrier. And it has some features not found on conventional benchtop spectrum analyzers, including its burst detect sweep mode function, which allows the MS2720T analyzer to register emitters as short as 200 μs. In fact, the burst detect sweep mode increases the analyzer’s sweep speed more than 1000 times in a 15-MHz span compared to a sweep performed without the function. This helps it to efficiently and effectively detect short-lived signals that nonetheless may be the source of interference to a communications system.

To assist with swept-frequency measurements, the MS2720T series analyzers can be equipped with tracking generators covering bandwidths of 100 kHz to 9 GHz, 100 kHz to 13 GHz, or 100 kHz to 20 GHz. These generators are impressive instruments in their own right, capable of 100-dB dynamic range, power steps as fine as 0.1 dB, and output power flatness of ±0.5 dB across the frequency range covered. For fixed-frequency measurements, each tracking generator includes a continuous-wave (CW) mode.

To find interference, the MS2720T analyzer offers a host of measurement capabilities, including spectrograms that can show signal events as a function of time, so as to detect and identify intermittent interference signals. When the analyzer is connected to a directional antenna, it can perform signal-strength measurements in search of interference sources, such as rogue transmitters. The 43-GHz MS2720T boasts the measurement convenience of other Spectrum Master portable analyzers, with dedicated routines for one-button measurements of field strength, channel power, occupied bandwidth, adjacent channel power ratio (ACPR), and carrier to interference (C/I).

The MS2720T Series analyzers are available with a wide range of options to enhance the in-field measurement experience, including options that tune the analyzer for measurements of the major wireless communications standards. These include LTE FDD/TDD, GSM/GPRS/EDGE, W-CDMA/HSPA+, TD-SCDMA/HSPA+, CDMA/EV-DO, and the WiMAX Fixed/Mobile standards. The analyzers can also be augmented by add-on kits, such as the electromagnetic-interference (EMI) probe kit that allows MS2720T Series users to troubleshoot EMI problems.

Identifying Interference

To assist with the difficult task of isolating interference sources, the MA2700A InterferenceHunter™ was developed for use with the Spectrum Master handheld analyzers, as well as with the company’s BTS Master™ and Cell Master™ handheld analyzers for cellular communications systems (it works with any of the analyzers equipped with the Interference Analysis option). The MA2700A InterferenceHunter is a handheld direction-finding (DF) subsystem that works with any of the handheld analyzers.

The MA2700A InterferenceHunter is effective at spectrum clearing and interference tracking, as well as when installing, deploying, and maintaining wireless networks. It incorporates a Global Positioning System (GPS) receiver and antenna, an electronic compass, and a user-selectable preamplifier. It connects to the analyzer by means of a Universal Serial Bus (USB) cable and requires no additional power source.

When armed with this subsystem, one of the MS2720T analyzers becomes a powerful interference detection and tracking tool. For an area of interest, a map can be stored within the analyzer. Once an interference signal has been detected, the MA2700A InterferenceHunter allows an operator to draw a vector line to the interfering source on the map. Operators can zoom on a section of the map to facilitate a search for an interference source.

The Spectrum Master MS2720T series analyzers are built for the field, in durable housings that weigh between 9.7 and 10.7 lbs (4.4 to 4.9 kg), depending upon model and options. All of the MS2720T series analyzers measure 12.4 x 8.4 x 3.7 in. (315 x 211 x 94 mm). To aid in the process of locating and identifying interference, Anritsu offers a 20-page application note, “RF Interference Hunting Techniques.” This document offers helpful guidance not only on spotting interference, but also on resolving the problems caused by it. P&A: $2600 (MA2700A InterferenceHunter); 4 to 6 wks.

Anritsu Co., 490 Jarvis Dr., Morgan Hill, CA 95037-2809; (408) 778-2000, FAX: (408) 776-1744.

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