niBT SA CFO Get Block Frequency Offset Trace VI

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Updated2023-02-21
3 minute(s) read

Returns the block frequency offset trace. The toolkit averages the trace over the number of acquisitions specified by the CFO Number of Averages property. The absolute values of the trace are used for peak hold averaging.

niBT SA CFO Get Block Frequency Offset Trace

niBT SA session specifies the niBT SA session refnum. Use this parameter to configure the behavior and operation of the appropriate NI Bluetooth Analysis Toolkit VI that accepts the niBT SA session refnum at its input.

error in describes error conditions that occur before this node runs. This input provides standard error in functionality.

niBT SA session out returns the niBT SA session refnum. Use this reference as the session input to subsequent VIs.

Note Close the niBT SA session refnum using the niBT SA Close Session VI before the VI completes execution to avoid possible memory leak issues.

CFO block frequency offset trace returns the data, including the block index, block interval, and the array of block frequency offset values for the block frequency offset trace.

x0 returns the block frequency offset for each block index. This value is set to 0.

dx returns the block interval. This value is set to 1.

y returns the array of block frequency offsets of the signal. This value is expressed in Hz.

The toolkit integrates the frequency of the FM demodulated signal starting from the center of the first preamble bit to the center of the first bit following the last preamble bit. This value is recorded as f₀. For LE-LR-125k packets, f₀ is computed by doing frequency integration from the start of the third preamble bit to the end of the 18th preamble bit.

For LE-LR-125k packets, the frequency offsets are calculated also for the three 16-bit groups after the 18th bit in the preamble and are recorded as f₁, f₂, and f₃.

The toolkit then integrates the frequency deviation of every x bits in the payload starting from the yth payload symbol and it is repeated until the end of the payload duration. The integral sums are recorded as f_n(n≥4 for LE-LR-125k packets and n≥1 for all the other packets).

For LE-Enhanced packets, x = 20 and y = 2.

For LE-LR_125k packets, x = 16 and y = 27.

For other LE packets, x = 10 and y = 2.

The toolkit calculates the block frequency offset as the difference between f₀ and f_n .

error out contains error information. This output provides standard error out functionality.

NI Bluetooth Analysis Toolkit

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niBT SA CFO Get Block Frequency Offset Trace VI

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