Searching for wireless interference

Observer Analyzer : Observer Analyzer : Real-Time Statistics : Checking the health of your network : Searching for wireless interference

The Wireless Site Survey tool displays activity by channels on your wireless network, detailed activity on the WLAN by channel, and allows you to search for wireless (Wi-Fi) interference, including its potential sources.

Note: Wireless Site Survey is only available using a supported VIAVI wireless driver.

To use the Wireless Site Survey tool and search for wireless interference:

♦On the Classic tab, in the Statistics group, click Wireless Site Survey.

If you want to scan multiple channels:

♦You must set the channels to scan in the Probe or Device Properties dialog, 802.11a/b/g/n Settings.

♦When Observer is scanning wireless channels, the other modes (such as Top Talkers, Access Point Statistics) will no longer be able to present a complete view of the network, as Observer’s data sample is limited to the current channel being scanned. Therefore, you should only use the Site Survey by itself.

See Table 9 for a list of noteworthy settings.

Table 9. Wireless interference
General Information Tab	This table summarizes essential information about what access points and stations are currently visible to wireless Observer. The status line at the bottom of the display shows all channels currently being scanned, highlighting each channel as it is looked at. Click Scan Setup to change the list of channels to scan.
Frame Type Tab	This table summarizes frame type totals for wireless data, management, and control packets.
Control Frames Tab	This table details control frames analyzed, including Power Save Polls, Requests to Send (RTS), Clear to Send (CTS), acknowledge (ACK), and CF (Contention Free) End packets.
Management Frames Tab	Displays detailed information about wireless management frames, including association requests and responses, reassociation requests and responses, ATIMs (Announcement Traffic Indication Message), and authentication/de-authentications.
Data Frames Tab	Displays detailed information about data frames on the wireless network.
Speeds Tab	Shows what stations are either transmitting (or receiving) wireless data at the various supported rates. To switch between transmitting and receiving speeds, click the down arrow next to the Tx (or Rx) and select the desired setting.
Signal Tab	Displays detailed statistics on wireless signal strength, quality, and data rates being used by stations and APs.
Channel Scan Tab	Shows the channel being tracked along with many statistics.

How Observer calculates wireless signal strength

A few of Observer’s wireless analysis modes display a metric labeled “signal strength,” expressed as percentage of the optimum signal strength. Table 10 shows how dB measurements are calculated into signal strength percentage.

Table 10. Wireless signal strength
Sensed (dB)	Reported (%)
1-3 dB	0%
4-22 dB	1%
23 dB	5%
24 dB	10%
25 dB	12%
26 dB	14%
27 dB	16%
28 dB	18%
29 dB	20%
30 dB	22%
31 dB	24%
32 dB	26%
33 dB	28%
34 dB	30%
35 dB	34%
36 dB	38%
37 dB	42%
38 dB	46%
39 dB	50%
40 dB	52%
41 dB	54%
42 dB	56%
43 dB	58%
44 dB	60%
45 dB	62%
46 dB	64%
47 dB	66%
48 dB	68%
49 dB	70%
50 dB	73%
51 dB	75%
52 dB	78%
53 dB	80%
54 dB	83%
55 dB	85%
56 dB	88%
57 dB	90%
58 dB	92%
59 dB	93%
60 dB	95%
61 dB	97%
62 dB	98%
63 dB	99%
64-257 dB	100%