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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.

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Tips for Measuring System Gain of a TMA

Carriers have come to rely on tower mounted amplifiers (TMAs) to help minimize dropped calls, loss of communication, and to provide more reliable service to customers. Field technicians are entrusted with ensuring the performance of TMAs so that all these benefits can be realized. An Anritsu Spectrum Master™ handheld spectrum analyzer will allow users to conduct the necessary measurements on TMAs quickly and easily. One of the most important measurements on a TMA after it has been installed is system gain, which verifies the TMA is operating properly. It requires using the system’s TX antenna to deliver a signal to the Rx antenna, as shown in figure below.
fig1
When measuring TMA gain, you need to consider the components in the receive path of the base station. The TMA should compensate for the receive cable loss. Additionally, the TMA may not be used for excessive level gains because it may make the defined Rx parameters impracticable at minimum and dangerous at the most. So, to ensure accuracy (and your health), follow these steps:
  • Measure the insertion gain/loss with the Bias Tee option turned off the Spectrum Master. Save the display.
  • Turn the Bias Tee option on. Take another insertion gain/loss measurement. Compare the two traces.
  • Calculate the dB gain by measuring the difference between the two traces.

  • Due to insertion losses in the system from cables, connectors, and antennas, the reference level used for measuring gain should not be 0 dB. The gain is the difference between measurements taken with the Bias Tee turned off and on. Remember, the gain of a TMA without a bypass switch cannot be measured. By connecting and disconnecting the power, it is possible to determine if the TMA is functional.
    fig2
    Relative gain measurement of a TMA, after installation, is very similar to other gain measurements, except for signal-level offsets, due to cable losses and the system isolation level shown by the blue line in the figure above. A good comparison of the amplifier plots before and after Bias Tee activation will not produce high accuracy. It will, though, provide a good test for operation and verification of a TMA-DD, TMA-D, TMA-S, or dual TMA-DD.
     

    Questions and Answers

    Question: Why is my signal accuracy poor when I have a wide bandwidth?

    Answer: In wide spans, the handheld spectrum analyzer can take many measurements for every display point. If a very narrow signal is being received and average detection mode is on, only a few of the measurement points would see the signal; the rest would see the noise floor. The average of those will cause a display that is less than the actual signal level.

    Question: How can I train new staff on how to use a Site Master™?

    Answer:We offer a few different training options. Authorized training is conducted through our dealers. Dedicated classes for just your employees, taught at a convenient location, are also available. Online demos of the Cell Master™ and Spectrum Master™, available through www.us.anritsu. com/smiu, can be helpful as well.

    Question: What is the difference in accuracy between the InstaCal™ module and precision calibration tee?

    Answer: InstaCal has a specified directivity of 38 dB for frequencies below 3.5 GHz while the regular calibration tee provides > 42 dB of directivity. The directivity is many times the largest contributor to measurement uncertainty and the difference between the two calibration techniques will affect the uncertainty. In general, it is recommended to use the InstaCal when you are looking for a fast way to make the calibration. If superior accuracy is most important, precision calibration tee is the best way to go.

     

    Test Tip

    Site Master cable and antenna analyzers are equipped with a cable loss mode that displays average cable loss of the swept frequency range. This is usually the preferred method, since there is no math involved. Just remember two things – increasing the RF frequency and cable length will increase insertion loss, and cables with larger diameters have less insertion loss and better power handling capabilities than smaller diameter cables. Tools of the Trade
     

    AM/FM/PM Analyzer Capability Available for Broadcast and LMR Applications

     
    MS2712E
     
    S332E

    Anritsu is committed to providing field technicians with the tools they need to accurately and easily measure professional broadcast and land mobile radio (LMR) signals. As part of that commitment, an AM/FM/PM analyzer option has been developed. Designed for the MS2712E/MS2713E Spectrum Master and S332E/ S362E Site Master analyzers, the option brings the inherent advantages of the industry leading handheld analyzers to professional broadcast and LMR applications.
    The AM/FM/PM analyzer provides analysis and display of analog modulation. Four measurement displays are available:

  • RF Spectrum View - A measured signal’s carrier power, frequency, and occupied bandwidth can be displayed with this view.
  • Audio Spectrum – You can view details of the demodulated audio spectrum, as well as the Rate, RMS deviation, Pk-Pk/2 deviation, SINAD, Total Harmonic Distortion (THD), and Distortion/Total.
  • Audio Waveform – If you need to see the time-domain demodulated waveform, this display can be accessed quickly and easily.
  • Summary Table Display – A synopsis of all RF and demodulation parameters can be seen simultaneously with this display.

  • These new testing capabilities complement the performance of the analyzers. Integrated multi-functional handheld test instruments, the MS2712E/MS2713E Spectrum Master eliminate the need to carry and learn multiple test sets. The S332E/S362E Site Master handheld cable and antenna analyzers allow users to easily and accurately conduct Return Loss, VSWR, Cable Loss, and Distance-To-Fault (DTF) measurements in the field.

     
     

    Leading Wireless Carrier Turns to Anritsu for New Testing Requirements

       
    Anritsu has been a tried and true supplier of handheld analyzers that have helped all the major carriers deploy, install, and maintain wireless networks worldwide for more than a decade. So, when one of the largest carriers in the United States had new testing requirements for the deployment of its UMTS Node Bs in northern California, it once again turned to Anritsu.
    Each of the UMTS Node Bs being deployed was designed with a Remote Radio Head (RRH). Simultaneously, the carrier was conducting an ongoing deployment of fiber linked distributed antenna systems (DAS) and T1/T3 fiber isolated backhaul installations, usually associated with cell sites located on high voltage power towers. The carrier was concerned that the field engineers and technicians lacked the experience and necessary tools to properly test the single-mode and multi-mode fiber links being used. Optical cables are much more sensitive than the copper lines, so the slightest error during deployment could have a major impact on overall network performance, especially dirty connectors.
     
    ms9090a


    The criteria that the carrier had established were demanding. The optical test solution had to be very small, easy to use, and have measurement “intelligence,” as the technicians were very familiar with RF and copper but had limited to no experience with fiber cables. In short, the criteria were similar to the features of two handheld analyzers the carrier had been using for years – Anritsu’s BTS Master™ and Cell Master™ – in different applications.
    Anritsu once again delivered an instrument that fit the bill. The carrier selected the Network Master™ MT9090A platform. Among the reasons for its selection was the MT9090’s ability to locate and determine the type of problem, as well as when it occurred. Another key feature was the MT9090A platform’s ability to measure up to 10 meters without the need for patch cable. Field users simply connected the fiber directly to the MT9090A and easily differentiated the internal fiber from the fiber under test.
    The MT9090A delivered all of this in an instrument that was small, easy to use, and had high resolution. The handheld instrument measures only 190 (W) x 96 (H) x 18 (D) mm and weighs less than 200 g. Additionally, all tests could be performed with only one or two buttons and results were given in a very clear Go/No Go indication.
    By offering the MT9090 platform, Anritsu was once again able to solidify its position as the test resource that can help Tier 1 customers with their rapid field deployment of new technologies.
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