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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...

   

How to Measure LTE eNodeB Output Power without Interrupting Service

LTE eNodeB output power needs to be measured regularly to provide the best possible user experience while complying with legal restrictions on maximum power output. The most accurate way to measure eNodeB output power is to put the eNodeB into a test mode and connect a power meter or spectrum analyzer to the transmitter. However, operators want to verify and set the eNodeB transmitter output power without using test modes, so they don’t block customer calls or lose revenue by taking the base station off air.
A convenient method to measure output power is to use a handheld instrument, such as the MT8221B BTS Master™, to demodulate and measure the LTE Reference Signal (RS) power. Power fluctuations make it impossible to directly measure maximum power while the eNodeB is in service. Power measurements of the RS, which UEs use for downlink channel estimation, can provide surprisingly accurate proxy measurements.
 
MT8221B
RS power measurement is defined as the average power of all of the subcarriers used for RS. Across a 10 MHz channel there are 50 Resource Blocks with 12 subcarriers each, for a total of 600 Resource Elements per symbol. Two of the subcarriers in selected symbols in each Resource Block are for RS from each transmitter. This gives a total of 100 RS Resource Elements in those symbols. When all the Resource Blocks are occupied and the Reference Signal Power is set to the nominal value, the RS subcarriers are at the same power level as the other subcarriers.
Reference Signal Power can be adjusted in many base stations, changing the relationship between total output power and RS power. The Reference Signal Power is not adjusted dynamically, only when the base station is taken out of service. For a particular base station, the relationship between the RS power and total power will be constant for a particular RS power setting.
A good technique is to first measure both actual transmitter power and RS power using the out-of-service measurement – with a test signal that has all subcarriers turned on. Measure the base station output power at the physical antenna port or at a coupler output with a known coupling factor, using a calibrated spectrum analyzer or a power meter.
Next, use a BTS Master to measure the RS power level at the same test point with the appropriate LTE option. If the RS power level is measured in the future, deviations from this measured value are a good indication that the maximum power has deviated by the same amount.
 

Questions and Answers

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

Answer: Yes. A feature in our Handheld Software tools allows you to convert a return loss measurement to DTF. In Handheld Tools, go to tools and select distance-to-fault. Enter the cable information and the software will convert your trace.

Question: Can I use the MS2024/26A VNA Master to test cable TV applications that have an impedance of 75 Ohms?

Answer: Yes. When using 75 Ohm matching pads you are limited to 3 GHz for your testing. You need to use a matching pad, part number 12N50-75B, and 75 Ohm calibration components. The calibration components are:

  • 22N75 Open/Short, DC to 3 GHz, N(m) 75 Ohms
  • 22NF75 Open/Short, DC to 3 GHz, N(f) 75 Ohms
  • 26N75A Precision Termination, DC to 3 GHz, N(m), 75 Ohms
  • 26NF75A Precision Termination, DC to 3 GHz, N(f), 75 Ohms

Question: What is the benefit of the Noise Marker feature?

Answer: The Noise Marker switches the detector type to RMS and normalizes the measured noise to a 1 Hz bandwidth. The value is reported in dBm/Hz. As the name implies, this detector is best used when measuring noise or noise-like signals.

 

Test Tip

A different approach to interference location is signal strength mapping. It only works for signals that are on the air for an extended period. Just drive around the area of interest, and capture signal strength and GPS location data. Place the measurements on a map and connect measurements of equal signal strength to form “isobars.” Unless the situation is very unusual, the isobars will form jagged circles around the signal source.
 

PIM Master™ Models for 850 MHz and 900 MHz Frequencies Introduced

 
MW8209A
 

Anritsu unveils two new PIM Master analyzers that cover the 850 MHz and 900 MHz bands, respectively. The models bring the inherent advantages of Anritsu’s patented Distance-to-PIM™ technology to cellular band networks and E-GSM networks, including UMTS Band VIII and LTE Band 8. Both the MW8208A (850 MHz) and MW8209A (900 MHz) are comprehensive trouble-finding tools that allow field technicians and engineers to accurately and quickly locate the source of passive intermodulation (PIM), whether it is in the base station antenna system or surrounding environment. No other test solution can locate PIM like PIM Master, thanks to Anritsu’s proprietary Distance-to-PIM. This one-of-a-kind technology helps pinpoints PIM, eliminating the unknown of whether the PIM source is from the antenna system or beyond the tower. Simple, immediate, and accurate, Distance-to-PIM simultaneously informs the user of the distance and magnitude of all the PIM sources.

 
Field personnel can use PIM Master to generate two high-power tones in the transmit band of a base station, and use any of the compatible handheld analyzers to measure the 3rd, 5th, or 7th order intermodulation products in the receive band that travel down the same cable. A unique feature of PIM Master is its 40 W testing, compared to alternative methods that only measure at 20 W. Using double the power allows the PIM Master to locate intermittent failures due to light corrosion, high-traffic loading, or changing weather conditions. It also permits users to find faults in a multicarrier antenna system or discover microscopic arcing in connectors.
 

BTS Master Holds Up to Challenges of Installing ATG System

   
When Mike Moderski and his team were given the assignment of installing the first Air To Ground (ATG) communications system for commercial and business aircraft, they knew they would have plenty to deal with. So, when they traveled throughout the United States to install towers on top of freezing cold mountains, and in hot and humid sites below sea level, they had to deal with something new every day. The only constant was the reliability and accuracy of the MT8222A BTS Master™ they used to ensure proper installation.
All told, Mike and his crew used the MT8222A on 92 base stations and 552 antenna systems in locations such as Venice, LA, which is a foot below sea level, and 14,000-foot high Wolf Peak, near Pagosa Springs, CO. Perhaps the biggest challenge, however, was a site in Dunphy, NV.
“It was one of the more memorable trips because we had to snow mobile with the gear strapped tightly to the back of the machine just to get to the site. Then, the engineers had to spend the entire night in white out conditions.”
 
MT8222A 

For Mike and his crew, the natural elements posed many different challenges. “We’ve been chased by elk, stalked by a mountain lion, and had to run from bears and snakes. We even had one site that was infested with rats,” he recalls. “Our test equipment was dropped, kicked, and bounced around all types of vehicles in all kinds of conditions across the country. One day it was sunny Florida, the next day it was mountains in Oregon and Washington. Temperature changes and rough handling didn’t affect the MT8222A. It delivered time after time.”
Dealing with the environmental conditions was only half of the story, though. The spectrum used for the ATG system is right above the cellular band, making it very susceptible to interference. Initial site assessments of RF conditions were critical to network success, so Mike and his team needed equipment that could locate interference and quickly trace the source so they could mitigate it. Only the MT8222A would do.
 
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