Hi,
In mmwave demo, BPM decoding is performed later in the chain inside the AoA2D DPU, but i don't find the code about bpm decoding in AoA2D DPU. Coule you please tell the bpm decoding in details?
If bpm decoding in time domain, the steps describles as follow.If bpm decoding after range and doppler fft, how to do decoding on RD Map? Thanks!
Hi,
Sorry for the delay
Please view the following document:
C:\ti\MMWAVE_L_SDK_05_03_00_02\docs\MmwaveDemo_documentation.pdf
At top of page 27:
The Doppler FFT size is equal to the next power of two greater than or equal to the number of physical chirps in the frame. Note that as currently the DPU supports only the 2Tx-BPM MIMO modulation with the uniform chirp distribution, the scheme can be viewed as a DDM MIMO modulation scheme. The processing per detected point at {rangeIndex, dopplerIndex} is illustrated in Figure 21.
The green block denoted by “Copy and Map” in Figure 21, per detected point, copies the symbols of the detected points from the Doppler FFT output memory in HWA to the local memory, performs the mapping, and copies back the symbols to the HWA memory for the angle FFT calculation. This operation is performed by the function aoa2dProc_CopyMapAntSymbols().The antenna symbols that are copied from the Doppler FFT output from the two locations into the local core memory are already BPM decoded. The mapping from the linear array from the local core memory into 2D antenna array y[col][row] in the HWA memory is performed using a table of type DPU_Aoa2dProc_compRxChannelBiasCfg which is constructed by the demo function MmwDemo_cfgDopplerParamMapping() during the configuration time based on the antenna geometry specified by the CLI configuration command antGeometryCfg.
So, BPM decoding is performed in a similar way as DDM decoding. Actually BPM is a simplified version of DDM.
I hope this helps
thank you
Cesar
The statement in the guide that states "BPM decoding is performed in the last DPU/AOA2D DPU in the processing chain" can be misleading. BPM decoding is inherently performed as part of the processing chain as highlighted below, the arrows show where the decoding occurs.
The BPM-MIMO scheme is observed as special case of a DDM -MIMO scheme (Doppler dDiision Multiplex MIMO scheme), with number of Tx antennas equal to 2, and phase increment (from chirp to chirp) of the second antenna equal to 180 degrees. So the BPM decoding is performed as inherent part of the DDM-MIMO scheme.
