17-03-2014, 02:53 PM
RF Carrier Suppression
Purpose:
To verify that the RF carrier suppression for the device under test (DUT) falls within
the conformance limits.
Resource Requirements:
• Vector Signal Analyzer (VSA), Rohde & Schwarz FSQ26 or equivalent
• HR/DSSS PHY Station with external antenna jack
• Associated HR/DSSS PHY AP or station with external antenna jack (optional)
• Controlling Software (Matlab)
Last updated: July 2010
Discussion:
Reference [1] describes the High Rate direct sequence spread spectrum (HRDS/SS) physical
medium dependent (PMD) sublayer for the 2.4 GHz band. Section 18.4.7 outlines the transmit
function and parameters associated with the PMD sublayer, and subclause 18.4.7.7 defines the
carrier suppression requirement.
This measurement assesses the transmit spectrum in the frequency domain. As the actual RF
carrier does not carry any information, it is suppressed during transmission to decrease the
transmit power. The carrier should be suppressed such that the suppression at the center
frequency is 15dB below the peak SIN (x)/x spectrum. Frequency offset of the carrier affects the
RF carrier suppression measurement. To make accurate measurements the frequency offset of
DUT at the channel center frequency is measured and the center frequency in carrier suppression
measurement is adjusted accordingly (Refer to Test # 19.2.7 Transmit Center and Symbol Clock
Frequency Tolerance)
Procedure:
1. Configure the DUT to transmit continuously with the scrambler disabled on channel 6 at
a bit rate of 2 Mbps at maximum output power.
2. Configure the VSA capture the spectrum of the transmitted waveform.
3. Compute the carrier suppression.
4. For enhanced accuracy, repeat step 2 multiple times and average the peak and suppressed
powers measured.
5. Repeat steps 1-4 for all supported channels.
Observable Results:
a. The RF carrier suppression measured at the channel center frequency should be at least
15 dB below the peak sin (x)/x power spectrum.