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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...

 

Spotting and Identifying Interference in the Field

Interference Hunter

Interference is a common problem in today’s crowded RF spectrum. In analog systems it will first appear as noisy links, and as limited range, dropped calls, or low data rate for digital transmissions. To restore network operation to optimum performance you have to spot interference and then identify the source so it can be fixed quickly. A common indicator of interference is a high noise floor in the receive channel. Once a high receive noise floor has been identified and located, it’s time to get a spectrum analyzer, such as the Spectrum Master™, out and begin your hunt. The first and best place to start looking is at the receiver input. If the receiver has a pre-filter, measure the signal after the pre-filter so you can view what the receiver and the receiver’s antenna see. It’s important to get a “visual ID” on the signal at this point so you can be sure you are on the same signal later.

Locating Interference
You need to look for interference on receive frequencies. If it’s a cellular issue, and the base station has a high noise floor, you need to be looking on the uplink channels. If the issue is mobile device reception, then look on the downlink frequencies. Two Way Radio and other Push-to- Talk systems often use the same frequency for both uplink and downlink so this distinction is less important.


Signal Characterization
As soon as you spot the interfering signal, characterize it before disconnecting from the receiver’s signal. Observe the signal’s shape, bandwidth, and behavior. Look for frequency drift, amplitude changes, and frequency hopping. If the signal is intermittent, or turns on and off, use Max-Hold to create an envelope. If you have spectrogram capability, use it to check for periodicity. For signals that are intermittent with a long time between appearances, it can be helpful to use a “Save on Event” capability.

When looking for signals that don’t belong on the receiver input, it’s important to know what signals are typically present in your bands. This can save a lot of time when hunting signals. If this is not possible, and often, it is not, it may be possible to demodulate the signal and listen for the station ID call sign.

 

3 Keys: Detecting Signals

Intermittent or “bursty” signals can be the bane of a field technician’s existence. Our burst detect feature has three keys that can release data so you can find these hard-to-locate, interference-causing signals.
 
  • Ability to make up to 20,000 measurements per second so users can see a 200 microsecond pulse every time, making it much easier to find burst signals.
  • A captured span that can be as wide as 15 MHz and as narrow as 20 kHz to simultaneously grab an entire span.
  • Display update of about 8 times a second; high enough so that the hardware max hold is useful and fast enough that the display updates frequently so signal changes will be quickly seen.

  • The Burst Detect feature can be found in these Anritsu instruments:
    • Spectrum Master™ MS2720T Burst Detect: 15 MHz
    • Spectrum Master™ MS272xC Burst Detect: 10 MHz
    • VNA Master™ MS203xC Burst Detect: 10 MHz
    • BTS Master™ MT822xB Burst Detect: 10 MHz
    • BTS Master™ MT8220T Burst Detect: 15 MHz
Burst Detect
 

Test Tip

“Live” connectors can damage sensitive measuring equipment. Avoid the costly repairs and unnecessary downtime associated with this problem by using an RF power indicator such as the MA25100A. Just mate the MA25100A to the connector in question and it will indicate the presence of high-level RF.
 

World´s First 40 GHz Handheld Cable and Antenna Analyzer

   
The Anritsu Microwave Site Master™ S820E is the world’s first handheld cable and antenna analyzer with frequency coverage up to 40 GHz. Additionally, the Site Master S820E will feature Vector Network Analyzer (VNA) measurement functionality. With dynamic range of 110 dB up to 40 GHz, the Site Master S820E brings performance typically only achieved with a benchtop instrument into the field. Best-in-class frequency resolution of 1 Hz provides maximum frequency flexibility for users. The wide frequency coverage provides high-resolution distance resolution, so field technicians can conduct more accurate DTF measurements. A powerful processor helps give the Site Master S820E a sweep speed of 650 us/data points. It also delivers the highest directivity in a handheld analyzer for maximum field accuracy. RF immunity of +17 dBm exceeds that of any other microwave handheld cable and antenna analyzer, so users can acquire stable, accurate measurements in the harshest RF environments. Site Master S820E conducts all key one-port measurements, as well as two-port transmission measurements and two-port cable loss tests. It also features Anritsu’s easyTest Tools™ and Line Sweep Tools™.   
S820E
 
 

Site Master Helps Tower Dog Overcome the “Impossible”

Matt Krick is like many tower dogs. He is up for any challenge, as long as he has his Anritsu handheld analyzer at his side. For a recent trip to South Getz Peak in Kingman, AZ, he relied on his Site Master to overcome freezing temperatures, a driving snowstorm, steep climbs and a slew of technical challenges. The job – deemed impossible by a site owner on an adjacent mountain – was to install a UHF amateur radio repeater with a 5 MHz split on the peak. There was considerable desensitization as soon as the repeater started transmitting, as its output would mix with the two of the three existing FM stations nearby and jam itself. After many failed attempts, the Site Master and its spectrum analyzer feature saved the day. "We turned on the UHF transmitter and walked around the mountain looking at the spectrum analyzer until we found the sweet spot where the input frequency remained clear. We put a tripod at that spot with some sheet metal and rocks to anchor it and set up the repeater antenna." Another issue was that the signal would drop on one of the translators whenever there was a heavy wind gust. Matt used the Site Master to easily determine that the wind rattled the ½-inch super flex jumper to the antenna so hard that the coax shield severed right after the connector, causing intermittent contact.

Environmental Issues
Matt also had to overcome the harsh environment. South Getz Peak rises 7,640 ft. above sea level and is home to harsh winds and frigid temperatures. Matt crawled through snow when it was -9° C during one visit. On another trip the snow was so dense the exhaust fan actually sucked a snow-drift into the building through the intake grates. The environmental and technical issues make the Site Master the perfect test tool. For Matt, the spectrum analysis and antenna analyzer functionality of the Site Master are the most handy. Size is a important factor, too. "When you’re climbing on your hands and knees through the snow to get to the site because the station is off the air, you can’t lug an 80-pound service monitor with you. The Site Master can fit right in your backpack and doesn’t weigh you down." 
 
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