17-03-2014, 02:47 PM
ERP-DSSS Transmit Spectral Mask
Purpose:
To verify the direct sequence spread spectrum (DSSS) transmit spectrum of the device
under test (DUT) is within conformance limits.
Resource Requirements:
• Vector Signal Analyzer (VSA), Rohde & Schwarz FSQ26 or equivalent
• ERP-PHY Station with external antenna jack
• Associated ERP-PHY AP or station with external antenna jack (optional)
• RF Power Splitter, Picosecond 5333 or equivalent
• Controlling Software (Matlab)
Last updated: April 2008
Discussion:
Reference [1] describes the Extended Rate Physical Medium Dependent (ERP-PMD) sublayer
for the 2.4 GHz band. Section 19.5 defines ERP operation specifications, and subclause 19.5.4
specifies the transmit spectral mask.
Two different transmit spectrums are defined dependant upon the desired modulation mode. The
transmit spectral mask for ERP-OFDM follows the spectral mask limits specified in 17.3.9.2,
while for ERP-DSSS the mask limits are as specified in 18.4.7.3. Subclause 18.4.7.3 defines the
transmit spectral mask to ensure multiple DSSS devices do not unduly interfere with each other.
Procedure:
1. For DUTs that support continuous transmission, configure the DUT to transmit
continuously on channel 6 at a bit rate of 11 Mbps at maximum output power. Otherwise,
configure the DUT to associate with the AP on channel 6 at a bit rate of 11 Mbps at
maximum output power; configure the AP to repeatedly transmit 100-byte ICMP echo
request packets to the DUT.
2. Configure the VSA to capture an entire packet. Capture the spectral mask of the
transmitted waveform.
3. For enhanced accuracy in burst mode, repeat step 2 multiple times and average the
spectral masks.
4. Repeat steps 1-3 for all supported data rates, channels, and PLCP header formats.
Observable Results:
a. The transmitted spectral mask of the DUT should fall within the conformance limits of
Figure 18-19.