mirror of
https://github.com/rtlsdrblog/rtl-sdr-blog.git
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fc5881d4cd
This commit adds the function rtlsdr_set_direct_sampling() which can be used to enable/disable a mode where the RTL2832 acts as a direct sampling receiver. This mode disables the tuner, and by attaching a long wire, or better, a 50Ω to 200Ω transformer and a lowpass- filter to the In-phase ADC input (pin 1 or 2 of the RTL2832, whereas pin 1 is at the molded dot) it is possible to listen to shortwave radio stations. The coupling capacitors can be left in place, but for better results they should be removed. Tuning in this mode is done with the DDC, and since the ADC samples with 28.8 MHz, tuning is possible from 0 to 28.8 MHz. Signed-off-by: Steve Markgraf <steve@steve-m.de>
297 lines
9.5 KiB
C
297 lines
9.5 KiB
C
/*
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* rtl-sdr, turns your Realtek RTL2832 based DVB dongle into a SDR receiver
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* Copyright (C) 2012 by Steve Markgraf <steve@steve-m.de>
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* Copyright (C) 2012 by Dimitri Stolnikov <horiz0n@gmx.net>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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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. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __RTL_SDR_H
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#define __RTL_SDR_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <stdint.h>
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#include <rtl-sdr_export.h>
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typedef struct rtlsdr_dev rtlsdr_dev_t;
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RTLSDR_API uint32_t rtlsdr_get_device_count(void);
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RTLSDR_API const char* rtlsdr_get_device_name(uint32_t index);
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/*!
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* Get USB device strings.
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*
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* NOTE: The string arguments must provide space for up to 256 bytes.
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*
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* \param index the device index
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* \param manufact manufacturer name, may be NULL
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* \param product product name, may be NULL
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* \param serial serial number, may be NULL
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* \return 0 on success
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*/
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RTLSDR_API int rtlsdr_get_device_usb_strings(uint32_t index,
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char *manufact,
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char *product,
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char *serial);
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RTLSDR_API int rtlsdr_open(rtlsdr_dev_t **dev, uint32_t index);
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RTLSDR_API int rtlsdr_close(rtlsdr_dev_t *dev);
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/* configuration functions */
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/*!
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* Set crystal oscillator frequencies used for the RTL2832 and the tuner IC.
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*
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* Usually both ICs use the same clock. Changing the clock may make sense if
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* you are applying an external clock to the tuner or to compensate the
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* frequency (and samplerate) error caused by the original (cheap) crystal.
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*
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* NOTE: Call this function only if you fully understand the implications.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \param rtl_freq frequency value used to clock the RTL2832 in Hz
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* \param tuner_freq frequency value used to clock the tuner IC in Hz
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* \return 0 on success
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*/
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RTLSDR_API int rtlsdr_set_xtal_freq(rtlsdr_dev_t *dev, uint32_t rtl_freq,
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uint32_t tuner_freq);
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/*!
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* Get crystal oscillator frequencies used for the RTL2832 and the tuner IC.
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*
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* Usually both ICs use the same clock.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \param rtl_freq frequency value used to clock the RTL2832 in Hz
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* \param tuner_freq frequency value used to clock the tuner IC in Hz
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* \return 0 on success
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*/
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RTLSDR_API int rtlsdr_get_xtal_freq(rtlsdr_dev_t *dev, uint32_t *rtl_freq,
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uint32_t *tuner_freq);
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/*!
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* Get USB device strings.
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*
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* NOTE: The string arguments must provide space for up to 256 bytes.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \param manufact manufacturer name, may be NULL
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* \param product product name, may be NULL
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* \param serial serial number, may be NULL
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* \return 0 on success
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*/
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RTLSDR_API int rtlsdr_get_usb_strings(rtlsdr_dev_t *dev, char *manufact,
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char *product, char *serial);
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RTLSDR_API int rtlsdr_set_center_freq(rtlsdr_dev_t *dev, uint32_t freq);
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/*!
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* Get actual frequency the device is tuned to.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \return 0 on error, frequency in Hz otherwise
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*/
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RTLSDR_API uint32_t rtlsdr_get_center_freq(rtlsdr_dev_t *dev);
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/*!
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* Set the frequency correction value for the device.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \param ppm correction value in parts per million (ppm)
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* \return 0 on success
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*/
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RTLSDR_API int rtlsdr_set_freq_correction(rtlsdr_dev_t *dev, int ppm);
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/*!
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* Get actual frequency correction value of the device.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \return correction value in parts per million (ppm)
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*/
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RTLSDR_API int rtlsdr_get_freq_correction(rtlsdr_dev_t *dev);
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enum rtlsdr_tuner {
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RTLSDR_TUNER_UNKNOWN = 0,
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RTLSDR_TUNER_E4000,
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RTLSDR_TUNER_FC0012,
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RTLSDR_TUNER_FC0013,
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RTLSDR_TUNER_FC2580,
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RTLSDR_TUNER_R820T
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};
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/*!
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* Get the tuner type.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \return RTLSDR_TUNER_UNKNOWN on error, tuner type otherwise
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*/
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RTLSDR_API enum rtlsdr_tuner rtlsdr_get_tuner_type(rtlsdr_dev_t *dev);
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/*!
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* Get a list of gains supported by the tuner.
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*
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* NOTE: The gains argument must be preallocated by the caller. If NULL is
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* being given instead, the number of available gain values will be returned.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \param gains array of gain values. In tenths of a dB, 115 means 11.5 dB.
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* \return <= 0 on error, number of available (returned) gain values otherwise
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*/
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RTLSDR_API int rtlsdr_get_tuner_gains(rtlsdr_dev_t *dev, int *gains);
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/*!
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* Set the gain for the device.
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* Manual gain mode must be enabled for this to work.
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*
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* Valid gain values (in tenths of a dB) for the E4000 tuner:
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* -10, 15, 40, 65, 90, 115, 140, 165, 190,
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* 215, 240, 290, 340, 420, 430, 450, 470, 490
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*
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* Valid gain values may be queried with \ref rtlsdr_get_tuner_gains function.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \param gain in tenths of a dB, 115 means 11.5 dB.
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* \return 0 on success
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*/
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RTLSDR_API int rtlsdr_set_tuner_gain(rtlsdr_dev_t *dev, int gain);
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/*!
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* Get actual gain the device is configured to.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \return 0 on error, gain in tenths of a dB, 115 means 11.5 dB.
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*/
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RTLSDR_API int rtlsdr_get_tuner_gain(rtlsdr_dev_t *dev);
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/*!
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* Set the intermediate frequency gain for the device.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \param stage intermediate frequency gain stage number (1 to 6 for E4000)
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* \param gain in tenths of a dB, -30 means -3.0 dB.
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* \return 0 on success
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*/
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RTLSDR_API int rtlsdr_set_tuner_if_gain(rtlsdr_dev_t *dev, int stage, int gain);
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/*!
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* Set the gain mode (automatic/manual) for the device.
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* Manual gain mode must be enabled for the gain setter function to work.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \param manual gain mode, 1 means manual gain mode shall be enabled.
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* \return 0 on success
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*/
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RTLSDR_API int rtlsdr_set_tuner_gain_mode(rtlsdr_dev_t *dev, int manual);
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/* this will select the baseband filters according to the requested sample rate */
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RTLSDR_API int rtlsdr_set_sample_rate(rtlsdr_dev_t *dev, uint32_t rate);
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/*!
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* Get actual sample rate the device is configured to.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \return 0 on error, sample rate in Hz otherwise
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*/
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RTLSDR_API uint32_t rtlsdr_get_sample_rate(rtlsdr_dev_t *dev);
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/*!
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* Enable test mode that returns an 8 bit counter instead of the samples.
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* The counter is generated inside the RTL2832.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \param test mode, 1 means enabled, 0 disabled
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* \return 0 on success
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*/
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RTLSDR_API int rtlsdr_set_testmode(rtlsdr_dev_t *dev, int on);
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/*!
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* Enable or disable the internal digital AGC of the RTL2832.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \param digital AGC mode, 1 means enabled, 0 disabled
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* \return 0 on success
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*/
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RTLSDR_API int rtlsdr_set_agc_mode(rtlsdr_dev_t *dev, int on);
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/*!
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* Enable or disable the direct sampling mode. When enabled, the IF mode
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* of the RTL2832 is activated, and rtlsdr_set_center_freq() will control
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* the IF-frequency of the DDC, which can be used to tune from 0 to 28.8 MHz
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* (xtal frequency of the RTL2832).
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*
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* \param dev the device handle given by rtlsdr_open()
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* \param direct sampling mode, 1 means enabled, 0 disabled
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* \return 0 on success
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*/
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RTLSDR_API int rtlsdr_set_direct_sampling(rtlsdr_dev_t *dev, int on);
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/* streaming functions */
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RTLSDR_API int rtlsdr_reset_buffer(rtlsdr_dev_t *dev);
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RTLSDR_API int rtlsdr_read_sync(rtlsdr_dev_t *dev, void *buf, int len, int *n_read);
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typedef void(*rtlsdr_read_async_cb_t)(unsigned char *buf, uint32_t len, void *ctx);
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/*!
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* Read samples from the device asynchronously. This function will block until
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* it is being canceled using rtlsdr_cancel_async()
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*
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* NOTE: This function is deprecated and is subject for removal.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \param cb callback function to return received samples
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* \param ctx user specific context to pass via the callback function
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* \return 0 on success
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*/
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RTLSDR_API int rtlsdr_wait_async(rtlsdr_dev_t *dev, rtlsdr_read_async_cb_t cb, void *ctx);
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/*!
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* Read samples from the device asynchronously. This function will block until
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* it is being canceled using rtlsdr_cancel_async()
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*
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* \param dev the device handle given by rtlsdr_open()
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* \param cb callback function to return received samples
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* \param ctx user specific context to pass via the callback function
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* \param buf_num optional buffer count, buf_num * buf_len = overall buffer size
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* set to 0 for default buffer count (32)
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* \param buf_len optional buffer length, must be multiple of 512,
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* set to 0 for default buffer length (16 * 32 * 512)
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* \return 0 on success
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*/
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RTLSDR_API int rtlsdr_read_async(rtlsdr_dev_t *dev,
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rtlsdr_read_async_cb_t cb,
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void *ctx,
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uint32_t buf_num,
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uint32_t buf_len);
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/*!
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* Cancel all pending asynchronous operations on the device.
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*
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* \param dev the device handle given by rtlsdr_open()
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* \return 0 on success
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*/
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RTLSDR_API int rtlsdr_cancel_async(rtlsdr_dev_t *dev);
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#ifdef __cplusplus
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}
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#endif
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#endif /* __RTL_SDR_H */
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