The UNS0122A-P 3BHE042393R0101 is a signal measurement of the fundamental frequency at a specific location on the WLAN board (Testing Point in Fig. 1), and the circuit is connected to two sets of testing points I+, I-, Q+, Q- after the Guard Interval (GI) Addition. These two sets of signals are differential signals of I and Q. Through a set of ADI’s differential signal to single end output circuit, we input the signals of I and Q into the PXI-9820 Digitizer in a single-end, two-channel way. the sampling rate of the PXI-9820 is set to 60MS/s, the resolution is 14-bit, and the trigger rate is set to 14-bit. The sampling rate of PXI-9820 is set to 60MS/s, the resolution is 14-bit, and the trigger mode is set to middle trigger.

UNS0122A-P 3BHE042393R0101 The transmitter baseband signal packet frame is generated by ADLINK’s own wireless card signal control program. The program generates the transmission frames repeatedly, and the preamble symbol sequences (including two short and two long symbols) of each packet are generated according to the training symbols of 802.11a specification, and the length and content of the data are arbitrary. The length and content of the data are arbitrary, and the time interval between packets is also arbitrary. In this test, the length of the data is set to 4096±n periods and the time interval is set arbitrarily.

UNS0122A-P 3BHE042393R0101 With the correct trigger mode setting, the PXI-9820 can accurately sample data from the beginning of each frame and then transfer the data of the whole frame to the memory of the PXI-3800 controller. With the powerful computing capability of the PXI-3800, all data is calculated in real time and the entire preamble and DATA portion is calculated as follows: (1) individual single-ended I and Q signals are converted to a complex signal (I+Qi, complex signal) (2) for each symbol, the first 16 points of the Cyclic Extension are discarded. (2) For each symbol, the first 16 points of Cyclic Extension are discarded and 64 points of FFT calculation are performed, totalling 2 short training sequences and 2 long training sequences of FFT calculation.