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Hello,
We tried inputting a 2.437 GHz sine wave at -40dBm from a signal generator into the RF A input of a Warp board running the 802.11 STA reference design. We were expecting to see a sine wave at the difference between the frequencies of the Warp board and the signal generator in Chipscope at ADC I and ADC Q. However we saw the following: http://i.imgur.com/OWmbUag.png . We captured the data through single run mode trigger. We would appreciate some help figuring out what is going on.
Last edited by NathanielTan (2017-Aug-01 15:13:54)
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I think you're seeing saturated I/Q signals due to clipping in the Rx RF circuits. The 802.11 Ref Design implements AGC. In between packets the Rx gains are set near the max. The Rx PHY pkt detection blocks search the incoming I/Q streams for preambles. When pkt det asserts the AGC logic estimates the Rx power and reduces the Rx gains accordingly.
To analyze raw waveforms I suggest using the WARPLab Reference Design. WARPLab provides easy functions for configuring the Rx gains and capturing raw I/Q signals for analysis in MATLAB.
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