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Handheld Users Group

Handheld Users Group

Delivering leading solutions for today's field and maintenance challenges

 
Interference hunter


With over 20 years leading the way in handheld testing Anritsu has a well earned reputation for superior measurements in not so superior conditions. learn more about the very latest handheld testing technology.

Click the article below to learn more...

   

Direction Finding Techniques to Find Interfering Signals

Direction finding is theoretically simple but in practice multi-path propagation often makes the process very complex. To do the job effectively, you need a map and a directional antenna that works at the frequency of interest.

Multiple Location Direction Finding
You can use directional antennas at multiple locations to approximate the site position of an interfering signal, if the signal stays on the air long enough to turn antennas to determine the direction of arrival. The Doppler direction finding method is better for short duration signals, as long as you are observing the direction of arrival display when the signal is on the air.


Single Antenna Direction Finding
To make measurements, determine your exact location on a map, then rotate the antenna to find the direction to the largest signal. Plot that information on the map with an arrow from where you are in the direction of arrival of the signal. Use an arrow rather than a straight line to record the direction of arrival. This is important when you are chasing a multi-path reflection. What you may see if that is the case is that the arrows point in all sorts of directions rather than toward a single point or small area.

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To see if you are being fooled by multi-path signals, move the antenna a quarter wave (figure 1) without rotating. If there is no significant change in signal strength, you probably are aimed properly. If, however, there is a radical shift in power you are experiencing multi-path reinforcement or cancellation, and the direction of arrival will be skewed. In urban environments, the main propagation paths will probably be multiple bounces off buildings. In this situation, don’t try to find the exact direction to the emitter. Stand at an intersection, point your antenna down all the roads and follow the strongest signal. Use a band pass filter tuned to the frequency range in which you are interested to eliminate the potential of having problems with strong out-of-band signals. Once you have gone past the emitter so that the direction of the strongest signal changes significantly, try triangulating the signal since you may have a direct path to the emitter. If you are still receiving the signal via indirect paths it will quickly become apparent. By this time, you will very likely be receiving a signal directly from the emitter so more traditional direction finding approaches will work.

Fixed Direction Finding Networks
In the ideal configuration of a fixed direction finding network, some receivers are around the coverage area and others are within the coverage area, so that at least two receivers would be able to receive a signal from the target area at right angles to each other. The worst case is if the two receivers receive the signal with opposite bearings. The signal could be anywhere along the line between the two stations and no triangulation is possible, as would be the case for antennas 2 and 6 trying to direction finding a signal originating at the X in figure 2. On the other hand, antennas 1 and 3 would give directional lines that would cross somewhere near the X.

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A completely different approach to interference location is signal strength mapping. It only works for signals that are on the air for an extended period of time. You can learn more about signal strength mapping in particular and direction finding in general by reading an application note that is available by clicking here.
 

Questions and Answers

Question: How do I get the fastest possible sweep time on my Spectrum Master™?

Answer: Sweep time is affected by the RBW, the VBW, the number of markers and the detector type. Use a wide video bandwidth, a relatively wide resolution bandwidth, turn off all markers and select the sample detector for the fastest sweep time. Also, use the minimum span to make the required measurements.

Question: How do I see both the maximum and the minimum of a signal at the same time?

Answer: The MS272xB, MS271xB and MT8222A have three traces available. The best way to see the maximum and minimum simultaneously is to set Trace A to Normal, Trace B to Max Hold and Trace C to Min Hold.

Question: Can I convert a return loss measurement terminated to an antenna to a DTF measurement?

Answer: Yes, our Handheld Software tools has a feature that allows you to convert a return loss measurement to DTF. In Handheld Tools go to tools and select Distance to Fault. Enter cable information and the software will convert your trace.

Question: What is the difference between the internal power meter and the high accuracy power meter on the handheld products?

Answer: The internal power meter uses the Spectrum Analyzer receiver to measure the channel power over a certain bandwidth. The high accuracy power meter uses an external RMS sensor, which makes a broadband power measurement. The sensor provides better accuracy than the internal power meter and is also better suited for making accurate measurements of modulated signals. The main advantage of the internal power meter is that you can make power measurements of specific channels and it filters everything outside the bandwidth you entered.

 

Test Tip

You can use the Synchronizing Signal (SS) from an LTE base station and a BTS Master™ to estimate LTE coverage. It’s more convenient and less expensive than drive test systems. An application note that explains it all is available at anritsu.com.
 

LTE Measurement Capabilities Expanded in Spectrum Master™ and BTS Master™

 
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Maintaining its market-leading position in LTE test, Anritsu has enhanced the LTE measurement capabilities in its MS272xC Spectrum Master and MT822xB BTS Master series of handheld analyzers. With the new analysis tools added to the existing measurement capabilities, field engineers and technicians have handheld instruments that can conduct nearly all the measurements necessary to successfully deploy, commission, and maintain LTE networks.
Among the new analysis capabilities are enhanced OTA functions, including a new Transmitter Test measurement capability that allows users to perform key measurements on an eNodeB transmitter in an OTA configuration when a direct connection is not possible. This also helps make the MS272xC and MT822xB the industry’s best field solutions for measuring Remote Radio Heads (RRHs).
The OTA option has new coverage mapping functions that allow users to quickly determine the downlink coverage quality in a specific location. S-SS, RSRP, RSRQ, and SINR can be plotted using five user-definable thresholds. From these measurements, the new scanner measurement screen shows up to six LTE sectors on the instrument display.
There are many other options and enhancements to help field technician’s commission, install, and maintain LTE networks. To learn more click here.

 
 

Anritsu Tops the List for Technician Team Scaling Snow-Covered Mountains

   
Matthew Myers has quite an extensive checklist when he goes out to install, commission or maintain towers for Union Wireless. Thermal hat, check. Snow pants, check. Snow shoes, check. Keys for the snow cat, check. First aid and rescue kits, check and check. Anritsu handheld instruments, check, check, and check.
It’s a far cry from a desk job but it certainly is one that brings with it a good story or two. That’s because Myers maintains nearly 40 different sites in Colorado, many of which can only be accessed using a snow cat from as early as October to as late as August.
“I’m responsible for sites that are found anywhere from 7,000 feet to 13,000 feet above sea level. We work in temperatures that range from -50° F to 100° F,” explains Myers. “It’s taken me as long as three days to just cut a trail to some sites.”
 
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These scenarios are almost standard operating procedure for Myers and his fellow technicians. Union Wireless has more than 120 cell sites that cover over 123,611 square miles throughout Wyoming, Northwestern Colorado, and parts of Utah. Everyone in his department does it all – from locating interference to commissioning, maintaining and troubleshooting microwave links, as well as GSM and UMTS architectures. For all these jobs at all these tough sites, Myers relies on Anritsu handheld analyzers.
“I can’t afford to make mistakes. Me and my team have to trust our vehicles, clothing, and each other,” said Myers. “My test gear is no exception. The results have to be accurate. I trust the results from all my Anritsu test gear.”
Myers will only rely on the BTS Master when he has to locate interference from other carriers, as well as repeaters. The BTS Master is also used along with the S820D Site Master™ to commission equipment, troubleshoot lines, and test benchmarks. He uses the S331C Site Master to accurately commission microwave links, as well as to maintain and troubleshoot them.
The Anritsu handhelds come in particularly handy when Myers has to head off to Baker’s Peak, an 11,942 foot mountain peak near Durango, Colorado. As Myers explained, last winter the winds reached 110 miles per hour and the top is so steep the antenna pipe mounts have been driven directly into the rock.
“We had trouble on Baker’s Peak and I had to pull a new temporary cable, plus carry my S820D to sweep the antenna. I couldn’t have done it with most other test gear.”
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