mirror of
https://github.com/PentHertz/OpenBTS.git
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22bc28edc4
This patch applies oversampling, when selected with 4 sps, to the downlink only, while running the receiver with minimal sampling at 1 sps. These split sample rates allow us to run a highly accurate downlink signal with minimal distortion, while keeping receive path channel filtering on the FPGA. Without this patch, we oversample the receive path and require a steep receive filter to get similar adjacent channel suppression as the FPGA halfband / CIC filter combination, which comes with a high computational cost. Signed-off-by: Thomas Tsou <tom@tsou.cc> git-svn-id: http://wush.net/svn/range/software/public/openbts/trunk@6747 19bc5d8c-e614-43d4-8b26-e1612bc8e597
180 lines
4.5 KiB
C++
180 lines
4.5 KiB
C++
/*
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* Copyright 2008 Free Software Foundation, Inc.
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*
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* This software is distributed under multiple licenses; see the COPYING file in the main directory for licensing information for this specific distribuion.
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*
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* This use of this software may be subject to additional restrictions.
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* See the LEGAL file in the main directory for details.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#include "sigProcLib.h"
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#include "GSMCommon.h"
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#include "LinkedLists.h"
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#include "radioDevice.h"
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#include "radioVector.h"
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#include "radioClock.h"
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/** samples per GSM symbol */
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#define SAMPSPERSYM 4
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/** class to interface the transceiver with the USRP */
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class RadioInterface {
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protected:
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Thread mAlignRadioServiceLoopThread; ///< thread that synchronizes transmit and receive sections
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VectorFIFO mReceiveFIFO; ///< FIFO that holds receive bursts
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RadioDevice *mRadio; ///< the USRP object
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int mSPSTx;
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int mSPSRx;
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signalVector *sendBuffer;
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signalVector *recvBuffer;
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unsigned sendCursor;
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unsigned recvCursor;
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short *convertRecvBuffer;
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short *convertSendBuffer;
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bool underrun; ///< indicates writes to USRP are too slow
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bool overrun; ///< indicates reads from USRP are too slow
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TIMESTAMP writeTimestamp; ///< sample timestamp of next packet written to USRP
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TIMESTAMP readTimestamp; ///< sample timestamp of next packet read from USRP
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RadioClock mClock; ///< the basestation clock!
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int receiveOffset; ///< offset b/w transmit and receive GSM timestamps, in timeslots
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bool mOn; ///< indicates radio is on
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double powerScaling;
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bool loadTest;
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int mNumARFCNs;
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signalVector *finalVec, *finalVec9;
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private:
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/** format samples to USRP */
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int radioifyVector(signalVector &wVector,
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float *floatVector,
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bool zero);
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/** format samples from USRP */
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int unRadioifyVector(float *floatVector, signalVector &wVector);
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/** push GSM bursts into the transmit buffer */
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virtual void pushBuffer(void);
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/** pull GSM bursts from the receive buffer */
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virtual void pullBuffer(void);
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public:
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/** start the interface */
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void start();
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/** intialization */
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virtual bool init();
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virtual void close();
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/** constructor */
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RadioInterface(RadioDevice* wRadio = NULL,
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int receiveOffset = 3,
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int wSPS = SAMPSPERSYM,
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GSM::Time wStartTime = GSM::Time(0));
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/** destructor */
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virtual ~RadioInterface();
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/** check for underrun, resets underrun value */
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bool isUnderrun();
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/** attach an existing USRP to this interface */
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void attach(RadioDevice *wRadio, int wRadioOversampling);
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/** return the receive FIFO */
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VectorFIFO* receiveFIFO() { return &mReceiveFIFO;}
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/** return the basestation clock */
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RadioClock* getClock(void) { return &mClock;};
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/** set transmit frequency */
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bool tuneTx(double freq);
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/** set receive frequency */
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bool tuneRx(double freq);
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/** set receive gain */
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double setRxGain(double dB);
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/** get receive gain */
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double getRxGain(void);
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/** drive transmission of GSM bursts */
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void driveTransmitRadio(signalVector &radioBurst, bool zeroBurst);
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/** drive reception of GSM bursts */
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void driveReceiveRadio();
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void setPowerAttenuation(double atten);
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/** returns the full-scale transmit amplitude **/
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double fullScaleInputValue();
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/** returns the full-scale receive amplitude **/
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double fullScaleOutputValue();
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/** set thread priority on current thread */
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void setPriority() { mRadio->setPriority(); }
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/** get transport window type of attached device */
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enum RadioDevice::TxWindowType getWindowType() { return mRadio->getWindowType(); }
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#if USRP1
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protected:
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/** drive synchronization of Tx/Rx of USRP */
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void alignRadio();
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friend void *AlignRadioServiceLoopAdapter(RadioInterface*);
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#endif
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};
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#if USRP1
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/** synchronization thread loop */
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void *AlignRadioServiceLoopAdapter(RadioInterface*);
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#endif
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class RadioInterfaceResamp : public RadioInterface {
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private:
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signalVector *innerSendBuffer;
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signalVector *outerSendBuffer;
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signalVector *innerRecvBuffer;
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signalVector *outerRecvBuffer;
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void pushBuffer();
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void pullBuffer();
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public:
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RadioInterfaceResamp(RadioDevice* wRadio = NULL,
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int receiveOffset = 3,
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int wSPS = SAMPSPERSYM,
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GSM::Time wStartTime = GSM::Time(0));
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~RadioInterfaceResamp();
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bool init();
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void close();
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};
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