Nuts About Nets AirHORN Overview

AirHORN is an RF signal generator capable of transmitting standard Wi-Fi modulated signals on the 2.4 GHz and 5 GHz ISM and UNII bands.

*Note – AirHORN does not support signal transmission in the 5GHz UNII-3 and ISM band (5.725 – 5.875 MHz).

The dual-band version of the product comprises a single USB adapter with internal antenna and a USB mount with cable extender for optimal device orientation and polarization. The single-band version comes with an external RP-SMA connector and 5dBi omni-directional antenna, offering the flexibility to use alternate external antennas. Installation of the product requires an available USB 2.0 port and Microsoft .NET 2.0 Framework. Older laptops and workstations with USB 1.1 ports will not work properly and the software will not initialize.

AirHORN is useful for RF antenna engineers when researching and developing wireless antenna propagation, amplifier performance, and receiver operation to ensure accurate signal transmission and reception according to desired specifications. It can also be used post-manufacture by wireless LAN engineers when designing and installing Wi-Fi networks, and is especially useful for directional and semi-directional antenna alignment. It can also be used in the absence of a Wi-Fi access point during pre-installation site surveys to identify optimal AP placement for complete RF coverage assessment as well as to avoid RF dead spots.

The signal generated by AirHORN is viewable with any spectrum analysis tool, such as the Cisco Spectrum Expert as shown in this demonstration.

Another good use for AirHORN is to combine its use with other network performance evaluation tools, such as NetStress, IxChariot, or Iperf to determine the negative impact that co-channel interference (CCI) and adjacent channel interference (ACI) can have on a Wi-Fi network from other RF sources. When combined, these tools can be used as a valuable training classroom lab aid to demonstrate these concepts to inexperienced wireless LAN engineers, to identify and measure the effects of neighboring RF impact to a Wi-Fi network, to generate impact assessment reports for management, and develop internal best practices around AP placement and channel overlap to minimize negative impact.

The product can also function as a denial of service (DoS) tool to cause severe disruption to a wireless LAN network since it utilizes 100% of available airtime (duty cycle). The signal generated by AirHORN is capable of completely wiping out a Wi-Fi network. However, the product is specifically designed to comply with all FCC regulations and IEEE standards for power output and transmission power is limited to 17dBm (50 mW). Also, AirHORN causes performance degradation in part because the signal transmission does not adhere to IEEE 802.11 medium contention rules and acts as a continuous transmitter.

Wireless LAN engineers should know that the tool is not automatically classified by Cisco CleanAir spectrum analysis access points. This is due to the CleanAir system architecture which splits RF signal processing between the Wi-Fi chipset and the SAgE spectrum chipset, with the focus of the SAgE chipset on non-Wi-Fi interference classification. The Wi-Fi modulated AirHORN RF signal is sent to the Wi-Fi chipset and are not processed by the SAgE chipset, with the resulting energy being interpreted as Wi-Fi adjacent channel interference and contributing to overall channel utilization. Therefore, the SAgE chipset and CleanAir system cannot classify the signal.

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