RigExpert IT-24 User manual

IT-24 RigExpert®
User’s manual
2.4 GHz ISM Band
Universal Tester

Table of contents
1. Description
2. Specifications
3. Using the tester
3.1. Before you start
3.2. Turning the tester on and off
3.3. Main Menu
3.4. Settings menu
4. Measurement modes
4.1. Return loss and SWR
4.1.1. Single-point measurement
4.1.2. SWR graph
4.1.3. Tester calibration
4.2. Transmitter power measurement
4.3. Spectrum analyzer
4.3.1. Peak and average levels
4.3.2. Density graph
4.3.3. Waterfall
5. Computer connection
5.1. Screen shots
5.2. Firmware updates
6. Examples of use
6.1. SWR measurement of antennas
6.2. Testing RF cables
6.3. Transmitter power measurement
6.4. Spectrum analyzer examples
6.4.1. The Wi-Fi protocol
6.4.2. The WiMAX protocol
6.4.3. The Bluetooth protocol
6.4.4. Proprietary data transfer protocols
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User’s manual
RigExpert IT-24 is a universal, ultra-portable
device for testing, checking, tuning or
repairing antennas and antenna feedlines of
the 2.4 GHz ISM band (operating frequencies
are 2.3 … 2.6 GHz).
The following tasks are easily accomplished
by using the IT-24:
• Quick tests of antennas and RF cables
• Output power measurement of wireless
access points and other transmitters
• RF environment monitoring (in the
spectrum analyzer mode)
IT-24 may be used by:
• Telecommunication providers to check
their own wireless data transfer networks
• Service companies to test the equipment
• Antenna and transmitter/receiver
manufacturers
Technologies:
• Wi-Fi
• WiMAX
• ZigBee
• Proprietary data transfer protocols
1. SMA connector
2. RP-SMA connector
3. Liquid crystal display
4. Keypad
5. Power on/off button
6. USB connector
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1. Description
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RigExpert IT-24
Single-point return loss and SWR (standing
wave ratio) measurement:
• Frequency range: 2.3 … 2.6 GHz
• Frequency resolution: 1 MHz
• Return loss measurement range: >2 dB
• SWR measurement range: 1 … 10
• Output power in this mode: about +5 dBm
• Measurement error limits are displayed by
the shaded area on the chart. These limits
are valid for the 2.4…2.5 GHz range.
SWR graph:
• 4 frequency sub-bands: 2.3…2.4 GHz,
2.4…2.5 GHz, 2.5…2.6 GHz, 2.3…2.6 GHz
• SWR display range: 1 … 5
Transmitter power measurement:
• Frequency range: 2.3 … 2.6 GHz
• Power limits: -20 … +25 dBm (0.01 …
300 mW)
• Input SWR of the power meter: less
than 1.5
• Measurement error: better than ±2 dBm
Spectrum analyzer:
• Display modes: peak and average levels,
density graph, waterfall
• Frequency range: 2.3 … 2.6 GHz
• Bandwidth of sub-bands: 100 MHz
(5 overlapping sub-bands), 20 MHz (30
overlapping sub-bands), 10 MHz (60
overlapping sub-bands)
• Input signal levels: about -100 … -20 dBm
• Signal level marks: 10 dB/div
• Receive preamplifier: -10 dB, 0 dB, +6 dB
Size: 17•8•3 cm
Operating temperature: 0…40 °C
Weight including batteries: 350 g.
RF connectors:
• RP-SMA for SWR and spectrum
modes
• SMA for power measurement
Interface:
• Color TFT display, 320•240 pixels
• Water-proof keypad, 9 keys
• Multi-language menus and help
screens
• Computer connection via USB port
Power:
• 4 pieces of AAA rechargeable or
alkaline batteries (the charger is not
included with the tester; batteries
are not charged inside the tester)
• From a computer USB socket
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2. Specifications

User’s manual
3.1. Before you start
Open the cover on the bottom panel of the tester. Install four fully charged 1.2V Ni-MH
(or four 1.5V alkaline) batteries, watching the polarity.
Do not:
– mix new and old batteries;
– use batteries of different types at the same time;
– overheat or disassemble batteries;
– short-circuit batteries;
– try to re-charge alkaline batteries.
To charge Ni-MH batteries, use charging adapters recommended for this type of
batteries.
Any leaks of electrolyte from the batteries may seriously damage the tester.
Remove batteries if the analyzer is not being used for a long time. Store batteries in a
dry cool place.
3.2. Turning the tester on and off
To turn the tester on or off, use the power button , located at the bottom left corner
of the keypad. When this button is pressed, firmware version number as well as battery
voltage are displayed on the LCD.
The on-screen menu system of the RigExpert IT-24 provides a simple but effective way
to control the entire device.
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3. Using the tester

RigExpert IT-24
3.3. Main Menu
Once the tester is turned on, the Main
menu appears on the LCD:
The Main menu contains a brief list of available commands. By using (up) and
(down) keys, menu items are selected. The (OK) key will then run a previously
chosen measurement mode. Just press (cancel) to return back to the main menu.
There is a power indicator in the top-right corner of the Main menu screen:
• The battery indicator shows battery discharge level. When the battery voltage is too
low, this indicator starts flashing;
• The USB icon is displayed when the analyzer is plugged to a personal computer or to
a DC adapter with USB socket.
The help system (a list of keys and their
functions) is built into the tester: there is
a “Help” item in the menu in each mode.
Here is an example of the help screen for
the main menu:
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User’s manual
3.4. Settings menu
The Settings menu (press the button in the main menu) is used to change the
setting of the tester, such as interface language, keypress sounds, colors, backlight,
splash screens and battery type. In addition, you may reset the tester to factory
settings.
There is a test mode to quickly check several operating functions of the tester. An SMA
to RP-SMA cable should be connected between the RF connector of the tester to run
the test mode. The following parameters are displayed: output power (with and without
the built-in attenuator); SWR at the input of the power meter. Normal values are marked
with green, while the red color indicates a problem.
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RigExpert IT-24
4.1. Return loss and SWR
4.1.1. Single-point measurement
In this mode, antenna or any other load is connected to the RP-SMA socket. Once this
mode is used for the first time, a simple calibration is required.
The following screen shot illustrates the return loss and SWR measurement mode:
The (left) and (right) keys change the operating frequency. To hold the
measurement, press the (ОК) key: you will then see the “H” pictogram in the top
right corner of the screen. Pressing the (menu) key will display a help screen for
this measurement mode.
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4. Measurement
modes

User’s manual
4.1.2. SWR graph
In this mode, antenna is also connected to the RP-SMA socket.
One of four frequency sub-bands may be chosen by pressing (left) or
(right) keys: watch the filled bar and the numbers at the bottom of the screen.
The OK) button will hold the measurement, displaying the “H” pictogram in the
top right corner of the screen. Pressing the (menu) button will display a help
screen.
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RigExpert IT-24
4.1.3. Tester calibration
To ensure the SWR measurements are accurate, it is necessary to calibrate the tester.
Following the instructions on the screen, just disconnect your antenna from the RP-
SMA connector; the calibration will then be done automatically.
In general, it is sufficient to perform calibration only once, after the tester is turned
on for the first time. However, it is recommended to re-calibrate the device if ambient
conditions, such as temperature, are significantly changed.
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User’s manual
4.2. Transmitter power measurement
By using an SMA to RP-SMA cable, connect your RF signal source to the SMA socket
of the tester. Please watch the difference between SMA and RP-SMA ends of the cable.
Please also make sure the RF power is
less then 1 Watt, since larger power may
permanently damage the tester.
Since some transmitters (such as Wi-Fi
access points) operate in pulse mode,
peak power (maximum measured power
over an interval of about 1 second) is
displayed on the screen.
As usual, the (OK) key will hold the measurement, and the (menu) button will
display a help screen for this operating mode.
4.3. Spectrum analyzer
There are three modes the RigExpert IT-24 can display spectrum of the input RF signal.
In each mode, you may press the menu button ( ) to set the scan bandwidth
(100 MHz, 20 MHz and 10 MHz) and the pre-amplifier mode (-10 dB – attenuator, 0
dB – turned off, +6 dB – turned on). In addition, you may set the refresh speed in the
waterfall mode.
The scan bandwidth, as well as scan bounds may be quickly changed by pressing
the (up), (down), (left) and (right) keys. This parameters are
displayed at the bottom part of the screen. The (OK) button will clear the screen.
Connect your antenna to the RP-SMA socket. Please notice that injecting high power
(such as an output of a wireless access point) into this socket may damage the tester.
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RigExpert IT-24
4.3.1. Peak and average levels
In this mode, different colors are used to display peak and average levels at each
frequency of the scanned range.
This mode is especially useful for detecting short peaks of the RF signal (such as data
from a sensor alarm).
4.3.2. Density graph
In this mode, color of each dot on the screen depends on how often the signal with a
certain level is detected. The color changes from blue (rare) to red (often).
This mode may be used for monitoring several sources of RF signal, received with
different levels at the same or at overlapping frequencies.
An example density graph is shown on the next page.
In the density graph mode, data is collected on the screen until the user presses
the (OK) key to re-start the measurement.
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User’s manual
4.3.3. Waterfall
In this mode, the screen is continuously filled with data (the “old” lines of the image are
replaced with “new” lines). The color of each point corresponds to the certain level of
the RF signal at a given frequency at the input of the tester.
Even small changes of the input signal are clearly visible, since the data is collected on
the screen for a long time.
The waterfall mode is recommended to monitor narrow-band signals with small levels,
which are not even visible in other modes.
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RigExpert IT-24
The RigExpert IT-24 may be connected to the USB port of a personal computer
running Windows operating system. All necessary drivers are installed automatically.
You may find the latest software for the IT-24 at the manufacturer’s website,
www.rigexpert.com.
5.1. Screen shots
The LCD2Clip program helps in transferring the screen shots of the tester to the PC.
Press the (screen shot) key after running this program, and the current screen
will be sent to the LCD2Clip.
The image is automatically copied into the clipboard, so you may then paste it into your
favorite graphics editor or send via e-mail.
5.2. Firmware updates
The latest updates of the firmware for the IT-24 are available at the manufacturer’s
website, www.rigexpert.com (please see the Downloads section).
Just run the FirmwareUpdate.exe and follow the instructions on the screen.
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5. Computer
connection

User’s manual
6.1. SWR measurement of antennas
While the ISM band covers frequencies from 2.4 to 2.5 GHz only, it is appropriate
to scan wider range (2.3 to 2.6 GHz) to see how the SWR curve behaves at different
frequencies.
In the first case, a simple antenna (taken from a Wi-Fi access point) was measured
(see the screenshots below). It can be easily seen that the minimum SWR (about 1.3) is
achieved at the very center of the Wi-Fi band. The values at 2.4 and 2.5 GHz are not very
high either (about 1.5), so it looks like the antenna under test is performing quite well.
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6. Examples of use

RigExpert IT-24
Next, a directional antenna (a planar array antenna with a gain of 15 dBi for 2.4 …
2.5 GHz) was tested. The SWR is only good at very ends of this frequency range, mostly
having very high values (more then 2). This indicates a poor quality of the antenna and/
or the cable.
In the third experiment (see the screenshot below), yet another antenna was connected
to the tester: a 17 dBi, parabolic reflector and a log-periodic feed.
It looks like this antenna has never been tested at the factory: the SWR curve looks
fully random.
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User’s manual
6.2. Testing RF cables
A cable under test is connected to the RP-SMA socket if the IT-24. The far end of the
cable should be terminated with a 50-Ohm dummy load. The load should have low
SWR (less than 1.2) at working frequencies.
A 1.8 meter long cable (diameter
approximately 5 mm) was connected to
the tester during the first experiment.
The measured SWR is under 1.3 in the
whole range of 2.4 to 2.5 GHz, which
indicates a good quality of the cable.
Since the characteristic impedance of
the cable is not exactly 50 Ohm, the SWR
curve is not too smooth.
Another cable shows much larger values
of the SWR (up to 1.6). This cable is
unlikely to be used for connecting
equipment in the 2.4 GHz ISM band.
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RigExpert IT-24
6.3. Transmitter power measurement
Two different Wi-Fi access points were connected to the IT-24 (by using an SMA to RP-
SMA converter cable) during this experiment. A “beacon” mode was activated, sending
data packets with 100-millisecond intervals.
The measured output power of the
first access point was 15 dBm. Then, a
possible measurement error (±2 dBm)
as well as a possible signal loss in
the converter cable (up to 1 dB) were
taken into the account. As a result, the
actual output power could range from
14 to 18 dBm. The power stated by the
manufacturer of the access point is
16 dBm, which is in good agreement with
measured values.
The other access point was only able
to show 11 dBm on the screen of the
IT-24. This value is too far from 17 dBm,
an output power according to the
manufacturer’s specifications.
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User’s manual
6.4. Spectrum analyzer examples
Thanks to the three spectrum analyzer modes, the IT-24 may be used to explore
narrow-band as well as wideband signals, differentiating these signals by power levels
as well as their distribution in frequency and time domain.
6.4.1. The Wi-Fi protocol
There is no doubt that this communications protocol is of a great interest to analyze
with the IT-24.
The picture above shows frequencies of all
14 overlapping Wi-Fi channels. Each channel occupies
20 MHz (in fact, up to 22 MHz). According to the
802.11n specification, 40 MHz channels may also be
used.
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RigExpert IT-24
A screen shot at the top (density graph)
shows the spectrum of a Wi-Fi access
point operating in the “beacon” mode
at the 1st Wi-Fi channel (the center
frequency is 2412 MHz, the range is 2401
to 2423 MHz). In the “beacon” mode,
data is transferred at low rate (1 or
2 Mbit/s), so the shape of the spectrum
form a Gaussian curve (looks like a bell).
When the data is intensively transmitted
(data rate is 54 Mbit/s), the shape
changes considerably — see the screen
shot in the middle. This is because the
OFDM modulation with 52 independent
carriers is used. The signal levels of all
carriers are the same, so the top of the
picture becomes relatively flat.
The screen shot at the bottom (a
waterfall mode) shows a transition
from the “beacon” transmission (top
of the image) to the intensive data
transmission (bottom of the image). The
wireless access point still transmits at
the 1st Wi-Fi channel.
The data packets of the “beacon” are
usually transmitted with a period of
100 ms. The packets are quite short
(less than 1 ms), so they are displayed
as individual dots inside the frequency
limits of the chosen Wi-Fi channel.
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