predet.c

DSP 5409 plc应用程序,调试通过,是用在电力线通讯上的演示程序.

//==========================================================================================
// Filename:		predet.c
//
// Description:		Functions related to preamble detection for power line modem.
//
// Copyright (C) 2001 - 2003 Texas Instruments Incorporated
// Texas Instruments Proprietary Information
// Use subject to terms and conditions of TI Software License Agreement
//
// Revision History:
//==========================================================================================

#include "ofdm_modem.h"

#define		FEQ_NORM_BIN		1					// use binary intervals to normalize in FEQ
#define		FEQ_NORM_DIV		2	 				// divide by power to normalize in FEQ
#define		FEQ_NORM_LOOKUP		3	 				// use lookup table for normalization in FEQ
#define		FEQ_NORM_NONE		4	 				// don't normalize in FEQ
#define		FEQ_NORM_TYPE		FEQ_NORM_DIV

//==========================================================================================
// Function:		frameAlign()
//
// Description: 	Main frame align and equalization function.
//
// Revision History:
//==========================================================================================
i16 *frameAlign(iCplx *freqEq, i16 *recSignal)
{
	i16				numFramesAve;		// count of frames averaged
	i16				frameStart;
	i16				frameStartFirst;
	i16				worstPwr;

	frameAligned = 1;			// Assume frameAlignment will turn out good
	//---- get average freq response until sync frame is received ---------
	numFramesAve = ddAveFFT( symbolArray, recSignal );
	//diagData(symbolArray, CARRIER_LEN, "avecar", diagICPLX);

	// If we didn't see enough frames with reasonable-looking phase error, 
	//  we're probably looking in the middle of a data packet, not a preamble,
	//  so treat this as a failed frame alignment.
	if (numFramesAve < 3)		//??? Make this into a defined constant
	{
		PostErrorCode(0xBAD7, "frameAlign", "preDet.c", "Insufficient number of frames averaged");
		#if SAVETRACE == TRUE
			SaveTraceData(0xBAD7);				//!!!DEBUG  Put a marker in the trace buffer
			SaveTraceData((u16)recSignal);		//!!!DEBUG  Put a marker in the trace buffer
			SaveTraceData(numFramesAve);		//!!!DEBUG  Put a marker in the trace buffer
		#endif
		frameAligned = 0;			// Frame alignment failed
		preambleDetCount = 0;		// Restart the frame detection process
		agcState = AgcIdle;			// Reset the AGC mode
	}
	else
	{
	
		//---- Calculate the impulse response from the averaged frequency values.  
		frameStart = getFrameStartFromImpulse( symbolArray );	// The maximum point in the 
																// impulse response corresponds
																// to the beginning of the frame.
		//#if COMPILE_MODE == MEX_COMPILE
			//frameStart += 1;      // DEBUG!!!!
			//mexPrintf("frameStart = %d\n",frameStart);
		//#endif
		frameStartFirst = frameStart;

		//---- re-do FFT averages at correct starting point and find sync frame -------
		recSignal = WrapRecPtr(recSignal, +frameStart*RX_SRC_INC); // Point to true start of a frame

		numFramesAve = ddAveFFT( symbolArray, recSignal );
		//diagData(symbolArray, CARRIER_LEN, "avecar2", diagICPLX);
	
		frameStart = numFramesAve*FFT_LEN
				   + (int)SYNC_FIELD_LEN 
				   + CYCLIC_PREFIX_LEN;
		recSignal = WrapRecPtr(recSignal, +frameStart*RX_SRC_INC); // set first data frame starting point

		worstPwr = getFreqEq( freqEq, symbolArray, numFramesAve );
		//diagData(freqEq, CARRIER_LEN, "freqEq", diagICPLX);
	
		#if SAVETRACE == TRUE
			SaveTraceData(0xC000 + (numFramesAve<<8) + (frameStartFirst&0x00FF));	//!!!DEBUG  Put a marker in the trace buffer
			SaveTraceData((u16)recSignal);		//!!!DEBUG  Put a marker in the trace buffer
			SaveTraceData(worstPwr);			//!!!DEBUG  Put a marker in the trace buffer
		#endif

		if( worstPwr < WORST_PWR_LIMIT )
		{
			#if COMPILE_MODE == MEX_COMPILE
				char	prtStr[80];
				diagData(symbolArray, CARRIER_LEN, "feqSymbols", diagICPLX);
				diagData(recSignalArray, RX_CIRC_BUFFER_LEN, "rxArray", diagI16);
				sprintf(prtStr, "signal power too low to equalize : %d\n", worstPwr );
				postError(prtStr);
			#else
				PostErrorCode(0xBAD2, "frameAlign", "preDet.c", "Signal power too low to equalize");
				#if SAVETRACE == TRUE
					SaveTraceData(0xBAD2);				//!!!DEBUG  Put a marker in the trace buffer
					SaveTraceData((u16)recSignal);		//!!!DEBUG  Put a marker in the trace buffer
					SaveTraceData(worstPwr);			//!!!DEBUG  Put a marker in the trace buffer
				#endif
			#endif
	
			frameAligned = 0;			// Frame alignment failed
			preambleDetCount = 0;		// Restart the frame detection process
			agcState = AgcIdle;			// Reset the AGC mode
		}
	}

	return recSignal;
}

	
//==========================================================================================
// Function:		aveFFT()
//
// Description: 	Get average FFT of the preamble frames.
//
// Revision History:
//==========================================================================================
i16 aveFFT( iCplx *aveCarrier, i16 *recSignal )
{
	u16				n, frame;			// loop counters
	u16				phaseError	= 0;	// sum(abs(phase)) for first n subcarriers,
										// used to determine end of preamble
	iCplx			*fftBuf;			// pointer to fft array
	iCplx			*aveCar;			// working pointer to ave data

  
	//---- initialize array used to average frequency response ------
	memset(aveCarrier, 0, CARRIER_LEN*sizeof(iCplx));	// set average to zero


	//---- get average freq response for N frames -----------------------
	for( frame = 0; frame < NUM_PRE_FRAMES+1; frame++ )  
	{	
		recSignal = circFFT( fftArray, recSignal );

		//--------------------------------------------------------------------
		//	Compare the phase of this frame with the phase of the previous frame.
		//	If the phase difference is greater that criteria, we must have hit
		//	the sync frame.  So don't incude this frame in the average and quit.
		//
		//	Note that we want to use the lowest freq frames so that any phase 
		//	shift due to sample rate error is as low as possible.
		//---------------------------------------------------------------------
		fftBuf = fftArray + CARRIER_LOW; // point to the carrier bins
		aveCar = aveCarrier;

		if( frame > 0 )
			phaseError = AlignPhaseCompare(PHASE_MEAS_LEN, aveCar, fftBuf );

		#if SAVETRACE == TRUE
			SaveTraceData((u16)(0xAA00 + (frame<<4) + phaseError));	//!!!DEBUG  Put a marker in the trace buffer (Shouldn't need to cast this, but Visual C++ complains)
			SaveTraceData((u16)recSignal);							//!!!DEBUG  Put a marker in the trace buffer
			SaveTraceData((u16)ReadRxDMAPointer());					//!!!DEBUG  Put a marker in the trace 
		#endif
		
		if( phaseError >= ALIGN_DONE_CRITERIA )
			break;
		
		//---- otherwise continue processing fft data -----------------
		for( n = 0; n < CARRIER_LEN; n++ )
		{
			aveCar->re += fftBuf->re;
			if( abs(aveCar->re) > 0x7000)
			{
				PostErrorCode(0xBAD4, "aveFFT", "preDet.c", "Overflow of real part of average carrier in preamble");
			}

			aveCar->im += fftBuf->im;
			if( abs(aveCar->im) > 0x7000)
			{
				PostErrorCode(0xBAD5, "aveFFT", "preDet.c", "Overflow of imag part of average carrier in preamble");
			}

			fftBuf++;
			aveCar++;
		}

//AVEFFT		#if SAVETRACE == TRUE
//AVEFFT			SaveTraceData((u16)(0x9800 + (frame<<4) + phaseError));	//!!!DEBUG  Put a marker in the trace buffer (Shouldn't need to cast this, but Visual C++ complains)
//AVEFFT			SaveTraceData((u16)symbolArray[5].re);			//!!!DEBUG  Put a marker in the trace buffer
//AVEFFT			SaveTraceData((u16)symbolArray[5].im);			//!!!DEBUG  Put a marker in the trace buffer
//AVEFFT			SaveTraceData((u16)(0x9900 + (frame<<4) + phaseError));	//!!!DEBUG  Put a marker in the trace buffer (Shouldn't need to cast this, but Visual C++ complains)
//AVEFFT			SaveTraceData((u16)fftArray[5+CARRIER_LOW].re);			//!!!DEBUG  Put a marker in the trace buffer
//AVEFFT			SaveTraceData((u16)fftArray[5+CARRIER_LOW].im);			//!!!DEBUG  Put a marker in the trace buffer
//AVEFFT		#endif

	}	// end of fft block
	
	if( frame == NUM_PRE_FRAMES+1 )
	{
		PostErrorCode(0xBAD6, "aveFFT", "preDet.c", "Failed to find Sync frame");
	}

	return frame;
}


//==========================================================================================
// Function:		ddAveFFT()
//
// Description: 	Get average FFT of the preamble frames.
//
// Revision History:
//==========================================================================================
i16 ddAveFFT( iCplx *aveCarrier, i16 *recSignal )
{
	u16				n, frame;			// loop counters
	u16				phaseError	= 0;	// sum(abs(phase)) for first n subcarriers,
										// used to determine end of preamble
	iCplx			*fftBuf;			// pointer to fft array
	iCplx			*aveCar;			// working pointer to ave data

  
	//---- initialize array used to average frequency response ------
	memset(aveCarrier, 0, CARRIER_LEN*sizeof(iCplx));	// set average to zero

	memset(fftArray, 0, FFT_LEN*sizeof(iCplx));	// DEBUG!!! 

	//---- get average freq response for N frames -----------------------
	for( frame = 0; frame < NUM_PRE_FRAMES+1; frame++ )  
	{	
		recSignal = circFFT( fftArray, recSignal );

		//--------------------------------------------------------------------
		//	Compare the phase of this frame with the phase of the previous frame.
		//	If the phase difference is greater that criteria, we must have hit
		//	the sync frame.  So don't incude this frame in the average and quit.
		//
		//	Note that we want to use the lowest freq frames so that any phase 
		//	shift due to sample rate error is as low as possible.
		//---------------------------------------------------------------------
		fftBuf = fftArray + CARRIER_LOW;
		phaseError = ddphase(PreambleArray, fftBuf, CARRIER_LEN );
		#if COMPILE_MODE == MEX_COMPILE  	
		{
			//char	vnameStr[20];
			//sprintf(vnameStr,"ddAve%d",frame);
			//diagData(fftArray, FFT_LEN, vnameStr, diagICPLX);
			mexPrintf("%d: phaseError %d\n", frame, phaseError );
		}  	
		#endif

		//if( frame > 0 )
		//	phaseError = AlignPhaseCompare(PHASE_MEAS_LEN, aveCar, fftBuf );

		#if SAVETRACE == TRUE
			SaveTraceData((u16)(0xAA00 +  phaseError));			//!!!DEBUG  Put a marker in the trace buffer (Shouldn't need to cast this, but Visual C++ complains)
			SaveTraceData((u16)recSignal);						//!!!DEBUG  Put a marker in the trace buffer
			SaveTraceData((u16)ReadRxDMAPointer());				//!!!DEBUG  Put a marker in the trace 
		#endif
		
		if( phaseError >= ALIGN_DONE_CRITERIA )
			break;
		
		//---- otherwise continue processing fft data -----------------
		fftBuf = fftArray + CARRIER_LOW;
		aveCar = aveCarrier;
		for( n = 0; n < CARRIER_LEN; n++ )
		{
			aveCar->re += fftBuf->re;
			if( abs(aveCar->re) > 0x7000)
			{
				PostErrorCode(0xBAD4, "aveFFT", "preDet.c", "Overflow of real part of average carrier in preamble");
			}

			aveCar->im += fftBuf->im;
			if( abs(aveCar->im) > 0x7000)
			{
				PostErrorCode(0xBAD5, "aveFFT", "preDet.c", "Overflow of imag part of average carrier in preamble");
			}

			fftBuf++;
			aveCar++;
		}

//AVEFFT		#if SAVETRACE == TRUE
//AVEFFT			SaveTraceData((u16)(0x9800 + (frame<<4) + phaseError));	//!!!DEBUG  Put a marker in the trace buffer (Shouldn't need to cast this, but Visual C++ complains)
//AVEFFT			SaveTraceData((u16)symbolArray[5].re);			//!!!DEBUG  Put a marker in the trace buffer
//AVEFFT			SaveTraceData((u16)symbolArray[5].im);			//!!!DEBUG  Put a marker in the trace buffer
//AVEFFT			SaveTraceData((u16)(0x9900 + (frame<<4) + phaseError));	//!!!DEBUG  Put a marker in the trace buffer (Shouldn't need to cast this, but Visual C++ complains)
//AVEFFT			SaveTraceData((u16)fftArray[5+CARRIER_LOW].re);			//!!!DEBUG  Put a marker in the trace buffer
//AVEFFT			SaveTraceData((u16)fftArray[5+CARRIER_LOW].im);			//!!!DEBUG  Put a marker in the trace buffer
//AVEFFT		#endif

	}	// end of fft block
	
	if( frame == NUM_PRE_FRAMES+1 )
	{
		PostErrorCode(0xBAD6, "aveFFT", "preDet.c", "Failed to find Sync frame");
	}

	return frame;
}


//==========================================================================================
// Function:		AlignPhaseCompare()
//
// Description: 	Compare phase of carriers from the previous frame with the phase 
//					of carriers from the current frame.  Decode to one of four phases 
//					(just like data decode) and sum the abs of the phase differences.
//