Signal Coverage Mapping Capability in Handheld Instruments Brings Greater Measurement Confidence to the Field
By Mark Heimbach, Anritsu Company

One of the biggest challenges associated with deploying, installing, and maintaining wireless networks is to assess the signal environment in which many of the antenna towers are constructed. Engineers and technicians responsible for wireless networks have had to rely on coverage estimation software while making assumptions about signal loss caused by terrain, buildings, and other factors.

While there have been advances that have made field instrumentation smaller and easier to use, and expanded their testing capability, little had been done with mapping…until now. New software that takes advantage of Google Earth has been developed for use with handheld field instruments, taking the guesswork out of mapping signal coverage. With actual measurement data detailing the signal coverage in a wireless network, it becomes much easier for users to define areas of poor signal strength.

Outdoor Mapping
Coverage mapping solutions, such as those available from Anritsu Company, provide wireless service providers, public safety users, land mobile radio operators, and government officials with RF coverage mapping capabilities. Field technicians and engineers can now use handheld analyzers to monitor RSSI and ACPR levels automatically. Using GPS, these signal levels are correlated with position, allowing detailed maps to be made of signal coverage throughout the network (Figure 1).

Using a map created with special software, such as Map Master from Anritsu, the test instrument can display all measurements overlaid onto actual maps of the coverage area. It can also display user-defined color codes corresponding to the power level. The refresh rate can be set up in time (1 sec min) or distance, depending on the user preference. The overall amplitude accuracy coupled with the GPS update rate ensures accurate and reliable mapping results.

When there is no valid GPS signal (such as the case in many indoor environments), the analyzers incorporate a start-walk-stop approach to record RSSI and ACPR levels. Users can set the update rate, as well as the start and end locations, and the interpolated points will be displayed on the map.

The start-walk-stop approach is particularly effective when measuring signal coverage indoors (Figure 2). Facility managers often need to verify public safety, broadcast and personal communication systems that operate throughout the facility. By overlaying RSSI and ACPR data onto a building floor plan, regularly verifying the performance of these critical functioning networks and being able to locate any areas of weak signal strength and sources of interference, many issues with poor in-building coverage can be avoided.

Once an area of weak coverage has been found, the ability to revisit that location to identify and correct the source of the problem is important. Setting up repeaters in poor coverage areas can often eliminate the problem. Taking these types of precautions can assure that the wireless network will remain error-free.

An added benefit is that outdoor map data can be converted to special image files that contain GPS data. The map can then be uploaded from an analyzer to a PC via USB. The overall amplitude accuracy, coupled with the GPS update rate, ensures accurate and reliable mapping results.

Performance at the Top of the Scale
Of course, the mapping capability is only advantageous if it’s used on an instrument that is highly accurate and can detect a variety of signal sources. Anritsu has developed its mapping feature for use with many of its “E” series handheld instruments, including the MS2712E/MS2713E Spectrum Master™ (Figure 3). Covering the 100 kHz to 6 GHz frequency, the new Spectrum Master can be equipped with a GSM/EDGE analyzer, W-CDMA/HSDPA analyzer, TD-SCDMA analyzer, CDMA analyzer, EV-DO analyzer, fixed and mobile WiMAX analyzer, LTE analyzer, ISDB-T analyzer, P25, and NXDN analyzer, thus eliminating the need to carry multiple instruments to the field.

Most importantly, the MS2712E/MS2713E handheld spectrum analyzers provide users with the high performance they need to detect interfering signals and monitor coverage. Some of the key specifications include:

Dynamic Range– Dynamic range is >95 dB in 10 Hz RBW, so the MS2712E/MS2713E can measure very small signals, even in the presence of much larger signals.

Displayed Average Noise Level (DANL)– With the built-in pre-amp, better than -152 dBm DANL can typically be realized in 10 Hz RBW and -162 dBm when normalized to 1 Hz. This low-level performance capability is essential when looking for low-level interference signals.

GPS-Assisted Frequency Accuracy– With the GPS option installed, the MS2712E/MS2713E has frequency accuracy of < 50 ppb. This additional accuracy is important when characterizing 3GPP signals using counted frequency markers. Also, all measurements can be GPS tagged for exporting to maps.

10 MHz Bandwidth Demodulation– This option allows users to verify RF, modulation, and downlink coverage quality for most wireless standards, including LTE, GSM, and W-CDMA.

Designed for Field Use
The Spectrum Master was designed specifically for field environments. Weighing less than 3.45 kg, it is small, compact and easy to carry. Its field replaceable Li-Ion battery typically lasts for more than three hours, and a bright 8.4-inch color display provides visibility – even in broad daylight. With an operating temperature range from -10° C to 55° C, a rugged case and splash-proof design, the Spectrum Master works in the most extreme weather conditions with guaranteed performance anywhere and anytime.

Conclusion
Mapping software is now available that complements the high performance of handheld analyzers to create test solutions that can help eliminate the guesswork when deploying, installing and maintaining wireless networks. The combination of features, functionality, and performance have helped field engineers and technicians ensure the optimum signal transmission in both public and government networks.
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Anritsu Company
www.us.anritsu.com
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