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IEEE-802.11b Simulator Software
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By Larson Automation
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The Software Overview
Larson Automation’s 802-11b simulator software simulates the demodulation process of 802.11b signal. It includes 6 processes: acquiring raw data from the air, validating the signal spectrum (power level and frequency), demodulating the data packet header, refining timing, decoding data packet header information, and interpreting data packet.
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The Demodulation Process
Acquire raw IF signal from the air
- Tuned to channel center frequency
- Scan signal for power ramp-up
- Used as the start of signal estimation
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RF Spectrum
- Start with Raw Data
- Perform Standard FFT through NI-Spectrum toolkit
- Standard Spectrum Analyzer display
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Unsynchronized I & Q
- Start with Raw Data
- Use NI-Demodulation toolkit (Convert IF to IQ.vi)
- Convert IF Data into baseband I&Q Components Based on ideal 11 MHz clock
- Removes the IF frequency
- Matches the original I&Q signals
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Modulation Power
- Start with Raw Data
- Extract the magnitude only information
- Convert to dB scale
- Note shift from BPSK modulation (header) to QPSK (Payload)
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I & Q Chips
- Start with Unsynchronized I&Q
- Recover frequency error
- Resample at actual DUT frequency (minus error)
- 802.11b Chip rate is 11 MHz
- Header Information is always BPSK at 1MHz data rate
- Lowest data rate uses 11 chips per bit
- 11 chips at 11 MHz = 1M bits per second
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Phase Cluster
- Calculate the I vs. Q relationship
- Remove the average offsets
- Calculate ideal waveform
- This information can be plotted on a constellation diagram
- Calculate EVM for the entire packet
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Request a copy ...Please put your address in the message field
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Larson Automation,
Inc.
Address: 960 Rincon Circle, San Jose, CA 95131
Tel: (408) 432-4800 Fax: (408) 432-4848 Email: info@larsonautomation.com
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