17-03-2014, 02:45 PM
Spurious Emissions Conformance
Purpose:
To verify if the device under test (DUT) is conformant with in-band and out-of-band
spurious emissions as set by regulatory bodies.
Resource Requirements:
• Vector Signal Analyzer (VSA), Rohde & Schwarz FSQ26 or equivalent
• ERP access point/station with external antenna jack
• Associated ERP AP or station with external antenna jack (optional)
• Controlling Software (Matlab)
Last updated: April 2008
Discussion:
Wireless devices are made up of a number of analog components and high-speed digital
components. The overall system emissions from a DUT are always a combination of emissions
from both of these types of components. These different combinations of signals in the
transmitter can cause spurious signals. The spurious emissions that fall in the system’s operating
band are called in-band spurious emissions. These emissions can cause interference with other
WLAN devices operating in the same band. The 2.4 GHz band is an ISM band (Industrial,
Scientific and Medical). Any interference above the limits specified by the regulatory bodies can
adversely affect the operation of the sensitive scientific and medical instruments operating in the
band. The in-band spurious emissions are measured to ensure that the interference to other
devices operating in the band is within the allowed limits.
Procedure:
1. Configure the DUT to transmit continuously on channel 1 at a bit rate of 11 Mbps at
maximum output power.
2. Configure the VSA to measure emissions from the DUT.
3. Observe emissions from the DUT.
4. Disable continuous transmission such that the DUT is in an idle state. Repeat steps 1-3.
5. Repeat steps 1-4 for channels 6 and 11.
Observable Results:
a. In all cases, all harmonics/spurs up to 10th harmonic must be at least 20 dB down from the
highest emission level within the authorized band as measured with a 100 kHz RBW.