Company X stacks several Local Area wireless Networks (LANs) on a single channel, as pictured above. WiPry-Pro Combo allows users to see the SSID information of each network across the 2.4GHz ISM band. The above image references the channelized LAN networks. for obvious networks and shown a significant RF power source near the higher end of the 2.4 GHz ISM frequency span. Many types of industrial machinery are known contributors to interference in the ISM band. For the newcomers, ISM stands for Industrial, Scientific, and Medical. Just about any type of modern machinery fits within the ISM definition and contributes to RF interference in the ISM frequency spectrum.
With SSID identification users can see which LANs are responsible for heavy traffic on a Wi-Fi channel and will possibly interfere with other users on the same channel.
From the image above the reader can see how the Wi-Fi traffic is localized to a single channel possibly to avoid an interfering source at the upper end of the ISM band. This is a common occurrence with industrial LANs where wireless network users operate in the same vicinity of "noisy equipment".
RSSI indicators give a qualitative measure to signal quality at the receiving end of the wireless communication link. Old CB radios have a squelch dial that allows users to select out and exclude the weaker received signals.
Measurement Equipment – No Simpler Than This
The figure above shows the simple equipment setup of an iOS device paired with Oscium’s WiPry-Pro Combo peak power meter and spectrum analyzer. Unlike other gimmick devices, Oscium provides users an industrial-grade spectrum analysis tool that independently analyzes content in the ISM band and ports it to the iOS device for display and user interface.
Measurements In An Industrial ISM Environment
The table below and accompanying figure are depictions of wireless networks operating in an industrial facility. From the collected data, Wi-Fi channel 11 is the obvious favorite for this company’s wireless network.
The figure below is output from WiPry-Pro Combo’s display with and an iOS device measuring the 2.4 GHz ISM band in an industrial complex. It’s interesting to note that aside from the wireless networks that occupy Channel 11, there is a significant energy source nearby. The color RED in the plot indicates highest persistence or energy levels. The industrial network has selected Wi-Fi channel 11 to avoid interference from whatever noise source occupies the higher frequencies.
Measurements In A Residential ISM Environment
In contrast with an industrial complex, the figures below are graphical depictions of the wireless network activity in an apartment complex. Each tenant subscribes to internet service through an ISP, and therefore when WiPry-Pro Combo scans the ISM band, there are SSID’s that appear at different frequencies. Do the individual users have any control over where their respective LAN’s broadcast in the 2.4 GHz ISM band? Probably not. Sure, there’s some radio button on a GUI buried beneath six layers of user interfaces that might help technicians change the user’s LAN channel, but that level of control is not usually accessible to the user.
Internet Service Providers and SSID’s
The most prevalent Internet Service Providers (ISPs) for the Philadelphia metropolitan area are listed in the screen shot below. The ISPs listed include these:
- Time Warner Cable
Each ISP uses a semi-unique service protocol for SSID naming and wireless LAN protection. Refer to the current promotional material for each provider to learn more about the available data rates for uplinks and downlinks. ISPs usually quote much larger bit rates for downlinks than uplinks because they assume most ISP users are interested in only downloading material. If you are uploading information for distribution to other, be sure to question potential ISPs about the uplink data rate provided under the advertised plan.
dBm? What’s The Power In Watts?
WiPry-Pro Combo has additional capabilities over its predecessor that allow users to see the actual EIRP for working Wi-Fi channels. EIRP is an industry acronym that stands for Effective Isotropic Radiated Power. The image below is a portion of MiniCircuit’s dBm –to –Watts conversion table. Since the Wi-Fi networks operate in a wireless power transfer environment, and WiPry gives users the RSSI information, its useful to see the operating power levels in the wireless network. This table not only provides dBm conversions to watts, but also for volts. The reader may find it interesting to see how few volts it takes over the air to pass Netflix video streaming information from a wireless router to his or her iPad, Android, or laptop.