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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.
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.
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
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.
|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
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.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
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.
The AM/FM/PM analyzer provides analysis and display of
analog modulation. Four measurement displays are available:
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
|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
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