Chanalyzer 4 User Guide

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Chanalyzer 4
Spectrum Analysis Software

Enjoy the satisfaction of a nearly perfect WLAN implementation.



Chanalyzer turns data collected from a Wi-Spy into highly interactive charts and graphs, allowing users to visualize their wireless landscape. Chanalyzer, combined with a wireless network card, can also display available access points as they appear in the spectrum, giving quick insight into whether interference is Wi-Fi or non-Wi-Fi related.
Together, Wi-Spy and Chanalyzer enable both enterprise, small business and hobbyist users to visualize, troubleshoot, and optimize WLANs. MetaGeek products are affordably priced to allow everyone, from individuals to large teams, access to professional-grade wireless spectrum analysis hardware and software.

What is a Wi-Spy?

A Wi-Spy is a portable USB spectrum analyzer, similar to a cable tester, but for wireless. It displays all radio energy in a frequency range, such as the 915 MHz, 2.4 GHz or 5 GHz public spectrum. Unlike a Wi-Fi card, the Wi-Spy is a fine-tuned piece of hardware that shows non-Wi-Fi activity emanating from devices like microwave ovens, automation systems, bluetooth, cordless phones, wireless security cameras, or anything else operating wirelessly in those frequencies. It also helps users determine a viable channel for network communications.

What is Chanalyzer?

Chanalyzer turns data collected from a Wi-Spy (and a wireless network interface card) into charts and graphs that will help users determine if they are experiencing interference. With a Wi-Spy, its' data can be found in the Density, Waterfall and Channels Table views. With a wireless network card, Chanalyzer displays available access points and can be found in the Networks Table and Networks Graph. If you are running Chanalyzer in a virtual machine, like VMWare, you will need to connect an additional USB Wi-Fi adapter to see specific network information.

System Requirements

• Wi-Spy 2.4x, Wi-Spy DBx, or Wi-Spy 900x hardware
• Built-In Wi-Fi card (for Wi-Fi features only)
• Microsoft Windows 7, Vista, or XP SP3
• .Net 3.5 framework
• USB Port

Installation

1) Download Chanalyzer 4 Software from MetaGeek.

http://www.metageek.net/products/chanalyzer-4/download

1. Open the downloaded file and double-click the installer.

2. Follow the installer prompts.

2) Run Chanalyzer

Click Start > All Programs > MetaGeek.

Select Chanalyzer 4 to launch the software.

3) Plug in a Wi-Spy

Chanalyzer requires a Wi-Spy 2.4x, Wi-Spy DBx, or Wi-Spy 900x USB Spectrum Analyzer. You can remove a Wi-Spy from a USB port at any time without ejecting.

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Choose a Wireless Network Interface Card (NIC)

Select a built-in or connected wireless network card in the main menu to access additional WLAN information about SSIDs, RSSI, MAC address and data rate. Click Wi-Fi in the menu bar, and then your wireless network card to collect Wi-Fi data in conjunction with the spectrum data. Wireless scanning is optional - Chanalyzer will continue to function if a wireless NIC is unavailable.

*Wi-Spy is a spectrum analyzer. It is not capable of reading at the Wi-Fi packet layer. Therefore Wi-Spy will not appear in the Wi-Fi card drop-down list.

Occasionally a wireless network card will actively perform probe requests on all Wi-Fi channels, creating noise across the entire band with power levels above -40dBm. This background activity can often skew results of a spectrum analysis site survey. If you notice this behavior with your wireless network card and don't want the additional noise in your recording, we recommend that you select No Wi-Fi Scanning.

See Wi-Fi Channels label on the Density View

In the main menu select View > Wi-Fi Channels. This will change the x-axis to display the Wi-Fi channels instead of the corresponding spectrum frequencies.

Navigation

Chanalyzer 4 provides controls for browsing Wi-Spy / Wi-Fi capture sessions or recordings. The navigation options are as follow:

Device Selector

Chanalyzer 4 continuously logs data from multiple sources when connected to your computer. When more than one Wi-Spy is connected to the computer at the same time, a “Device Selector” dropdown box will appear in the lower left corner of the Chanalyzer 4 window. The top most device in this list will be whichever Wi-Spy you plugged in first. With a Wi-Spy 2.4x and Wi-Spy DBx both connected, you can record both the 5.4 GHz and 2.4 GHz spectrums simultaneously.

Session Navigator

Each time a user selects a new frequency range in the Wi-Spy menu the previous data is saved as a session in a Wi-Spy Recording. The Active Session is the one that is selected in the dropdown Device Selector box. With two Wi-Spy devices, Chanalyzer can simultaneously log the 2.4 GHz and 5 GHz spectrums; simply select the DBx from the Device Selector, then the “Full 5 GHz Band” option from the Wi-Spy menu. When you have an additional Wi-Spy connected, like the 2.4x, it will have the “Full 2.4 GHz Band” option selected by default. When opening a recording in Chanalyzer 4, the Sessions are selected from the dropdown menu in the lower left corner.

Timespan Controls

The Timespan controls adjust the length of time users see in the Overview and Details panes. Timespan adjustments allow users to narrow-in on anomalies and moments in time when WLAN performance suffered. The playback buttons are used to Play, Pause, Rewind, and Fast Forward while viewing a capture. The up and down arrows in the playback controls can also aid in selecting smaller time spans in the waterfall navigation.

Timeframe Navigation

To move to a specific position within the session, click-and-drag the playheads along the time bar. You can also click-and-drag the head and tail of the highlight slider region to easily adjust the timespan in the Waterfall Navigation.

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Overview Pane

This pane, located in the top of the display window, contains the Waterfall and Density views.

The Density View displays how often a signal is detected at a specific amplitude. After a short time of gathering data, patterns begin to emerge in the Density View.
A density map view enables the user to quickly identify packet-based and analog patterns that may be interfering with your network.

Display Options

The Density View has several view options. All of the display options can be toggled on and off as needed. Users can employ combinations of these options to troubleshoot more efficiently.

Current

The current display option represents the received values at the most recent reading in the time span. By default this will be real-time unless the user has changed the time span settings to previously captured data.

Average

The average display option represents the average of the received spectrum activity in the selected time span. For example, if the time span is 1 minute, the average will be calculated in the rolling 1 minute.

Max

The maximum display option represents the maximum values received from the Wi-Spy across the band in the selected time span.

Color by Amplitude

Chanalyzer creates a density map of the most used frequency amplitude points in the selected time span. The less trafficked frequency points appear more transparent, while high-use frequencies appear more bright or intense.

Chanalyzer uses color to represent amplitude height. Reds indicate higher amplitude and dark blues represent lower amplitudes.

Color by Density

The more often a signal is detected at a specific amplitude and frequency, the brighter the point on the graph becomes. High density signals are represented by red, and low density signals are represented by dark blue.

Color by Utilization

This view emphasizes how constant noise is across the spectrum. At any given point, Chanalyzer assigns a color based on how much of the energy in a range of time is above that point. If 50% of all the activity is above an amplitude point, Chanalyzer colors it red. This display option is especially useful in understanding how constant interference is within a given range of time.

Networks

By selecting SSIDs in the Networks Table Chanalyzer will draw overlays in the density view to help the user interpret which may be experiencing the most congestion.

Inspector

This creates a hovering box above the cursor that displays specific numbers regarding a particular frequency amplitude point.

Waterfall View

This view graphs amplitude over time for each frequency in the selected ISM band. The Waterfall View uses a color scale to represent amplitude levels – low are dark blue while high amplitudes are bright red. This emphasizes instances where wireless devices like cordless phones or microwaves may have changed the spectrum. For example, when a microwave is started or a cordless phone changes channels, it is very noticeable in the Waterfall View.

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Details Pane

The details pane contains a number of tabs with more in-depth information about Wi-Fi networks and their channels. You can quickly alternate between tabs by pressing CTRL + TAB.

Networks Table

The Networks Table is a list of all the Wi-Fi access points that are within range of your computer’s Wi-Fi cards current location.
The names (or SSIDs) of access points (APs) are displayed, along with signal strength (RSSI), channel, MAC address and other identifiers. This table provides a snapshot of Wi-Fi networks in the area, and helps correlate RF activity in the spectrum views to known Wi-Fi networks.
To see a network drawn in the Density View or Networks Graph, click the check box next to its name.

Networks Table Filters

The Networks Table filters allow you to exclude or include SSIDs that meet your filter criteria. You can filter by SSID, vendor, channels, network type, and security. This can be very useful if you are in an area with dozens of AP’s and you only want to view certain networks, for example, networks centered on channel 6. The filters can be stacked to meet a variety of criteria.

The SSID or Vendor filter begins with a “+” or “-” option. This will determine whether the include or exclude the following text entered. For example, if you do not want to see any wireless networks named “MetaGeek”, select the - radio button and enter “MetaGeek” in the SSID or Vendor field. Press enter to apply the filter. Chanalyzer will then show every network that doesn’t have “MetaGeek” in the SSID or hardware field.

To filter by channels click the arrow on the drop-down menu which will allow you to choose between 2.4 GHz and 5 GHz channels. 2.4 GHz channels range from 1-14 and 5 GHz channels from 36-165. “-” will filter the channels from a to b. For example, typing (1-6) will show channels 1 through 6. Using a “,” will allow you to enter multiple single channels to view. Typing (1, 4, 6, 9) will show only those channels. You can also use a combination of the two operators as follows: (2-5, 7-10).

The remaining filter options will show either AdHoc or Infrastructure networks or exclude certain security settings of SSIDs.

To remove filters click the x next to the box below.

Sort by RSSI to find the strongest or weakest nearby network.

Within Chanalyzer, you can sort by RSSI by clicking the “RSSI” table header. This will sort detected wireless networks by ascending/descending order showing which have the strongest or weakest signal as compared to where you are at that moment. We recommend viewing networks with an RSSI value above -85dBm.

Networks Graph

Click the Networks Graph to show signal strength over time, drawing the rows selected in the Networks Table. Drops in signal strength indicate poor signal coverage and can be referenced against the Waterfall and Density views to determine if interference is to blame.

Please note, this data comes from the wireless network card and not the Wi-Spy.

Channels Table

Current – The current represents an average of the most recent amplitude readings within the channel range.


Grade – This calculation uses the entire 20 Mhz width of a Wi-Fi channel. Higher power levels near the center of the channel will affect the grade more negatively. A high grade of 90 or above can be interpreted as an “A” while 80 or above is a “B.” Anything below 70 is not recommended for Wi-Fi deployment.

Average - For each channel range (for example, Wi-Fi Channel 1, 2401 - 2423 MHz), Chanalyzer calculates the average power within that channel frequency range.

Max - This is the highest amplitude point within the Wi-Fi channel frequency range.


Utilization – The percentage of all noise above a defined amplitude threshold. The default amplitude is -85dBm.


Networks – Once network scanning is initialized Chanalyzer will count list the amount of networks detected.

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Identifying Interference

Most modern spectrum analyzer solutions offer some form of automatic device classification, although many are rudimentary and can produce false positives. You can train yourself to identify interfering devices much faster and more accurately than any automatic tool simply by familiarizing yourself with transmitter modulation patterns. Here are a few items to test with a spectrum analyzer:

• Neighboring APs occupying an overlapping channel
• Cordless Phones
• Microwave Ovens
• Wireless Audio transmitters
• Video Transmitters (Security Cameras, IP cameras)
• PIR motion detectors
• WLAN download
• WLAN upload

Common Shapes: Wi-Fi - 802.11b

This is the most common shape you are likely to see when troubleshooting Wi-Fi in the 2.4 GHz band. APs tend to transmit beacons at the lowest common rate of all Wi-Fi devices, or the most basic modulation, BPSK. This image shows APs on channels 1, 6, and 11.

Common Shapes: Wi-Fi 802.11g ERP-OFDM

Identify 802.11g ERP-OFDM by looking for a flat top. The flat top of OFDM signatures are under 20 MHz wide. This is the same signature for 802.11a OFDM.

Common Shapes: Wi-Fi - 802.11n 2.4 GHz 40-MHz ERP-OFDM

802.11n OFDM APs with data rates of 300mbps use channel bonding, which appears as two 802.11g ERP-OFDM signatures bonded together.

The width of an 802.11n AP transmitter will not always be 40 MHz. In most cases, 40 MHz transmissions appear in bursts when an AP’s throughput exceeds the capabilities of 802.11g ERP-OFDM.

You can see the bursts in the waterfall view very easily. 802.11a/g/n typically shows abrupt edges, due to the dBm drop on each side of the signatures.

Common Shapes: Adjacent Channel Interference

Your Wi-Fi may be on the same channel as other wireless APs. There are 11 channels in 2.4 GHz, but only three that don’t overlap (1, 6 and 11 in the U.S.). When APs are placed on overlapping channels they must wait for neighboring APs to stop transmitting before they can.

Common Shapes: Microwave Ovens

Microwave Ovens operate in the 2.4 GHz range, typically creating a shape similar to a mountain slope in the Density View. Since microwaves are usually used from 1-5 minutes, it helps to adjust the timespan to about two minutes.

Interference occurs when the microwave oven transmits on the same frequencies as the Wi-Fi channel. In this image, you can see how the mountain-shaped microwave oven covers the curvature of the Wi-Fi on channel 11.

Microwave amplitude levels vary depending on their distance from the spectrum analyzer. Experiment with a microwave oven and varying locations.

You can also use the Waterfall View to help you identify microwave interference, because it shows how long a device is active, and will often show a distinctive “comma” shape when a microwave is used.

Common Shapes: Motion Sensors

Motion sensors tend to transmit within very narrow frequency ranges. Sometimes a building will have motion sensors in each room. If this is the case, verify that they are not in the 2.4 GHz range by walking close to each sensor and watching the corresponding amplitude levels in the Waterfall View.

Common Shapes: Audio Video Transmitter

Wireless security cameras generally create three spikes in a 20-30 MHz wide frequency range. They constantly transmit and rarely change channels. Look for three adjacent vertical lines in the Waterfall View.

Common Shapes: Cordless Phones

Not all cordless phones create the same pattern; some are very narrow and use the 2.4 GHz frequency band, while others scan for the clearest channel and vary in the frequencies used.

One of the easiest ways to identify cordless phone interference is by using the Waterfall View to search for a unique series of vertical lines. When a cordless phone changes channels, it will appear as a break in the waterfall.

Some cordless phones may hop across the entire spectrum similar to Bluetooth.

Common Shapes: Bluetooth

Bluetooth hops across the 2.4 GHz 1,600 times a second, which is a form of frequency-hopping spread spectrum (FHSS) modulation.

Because frequency-hopping transmitters broadcast across large frequency ranges, they may cause WLAN degradation, though it is unlikely that Bluetooth will cause severe interference.

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Wi-Spy Configuration Settings

The Chanalyzer software operates similar to a DVR. It will automatically save all of the Wi-Spy data it has seen since the program was initialized. If the user changes frequency range, the old data will be stored into a session within the Wi-Spy capture. When opening a captured session, the user navigates between them using the Recordings Navigator in the bottom left corner.

There are two methods to change the start and stop frequencies displayed in Chanalyzer. Click and drag the mouse across the frequency range you would like to view in high resolution or use the pre-defined Wi-Spy configurations in the main menu under Wi-Spy.

Click-and-Drag Wi-Spy Configuration

To view a higher resolution of a smaller frequency range, click, hold down the mouse button, and drag across to highlight range you would like to view. Upon releasing the mouse button a contextual menu will appear. Click Zoom. Chanalyzer will then store the previous data in another session and start a new one. You can view it at any time by clicking on the session navigator.

Wi-Spy Configuration Presets

Chanalyzer includes pre-defined zoom settings that have been optimized for speed and resolution. Access these shortcuts in the top main menu under Wi-Spy. Choose the Wi-Fi channel range you would like to monitor.

View a Previous Capture

Since Chanalyzer continuously logs all spectrum data, previous configurations and settings are stored in a unique session and can be viewed at any time during the capture. Viewing a previous capture will not interrupt the current live capture session.

Return to Previous Wi-Spy Settings

Chanalyzer saves the most recently used Wi-Spy configurations in the main-menu. To return to a previous setting use the main menu Wi-Spy option to return the previous setting.



LEARN MORE

You can learn more about Chanalyzer 4 on our website at
http://www.metageek.net/products/chanalyzer-4