A low level binding to the librtlsdr library for Node.js.
This module requires that you have librtlsdr installed on your system. In turn librtlsdr requires libusb.
You can install librtlsdr with most package managers which will ensure you have the right dependencies.
Homebrew (macOS):
brew install librtlsdr
Debian based Linux distros:
apt-get install librtlsdr-dev
npm install rtl-sdr --save
const rtlsdr = require('rtl-sdr')
// Get number of connected RTLSDR devices
const deviceCount = rtlsdr.get_device_count()
if (!deviceCount) {
console.log('No supported RTLSDR devices found')
process.exit(1)
}
console.log('Found %d device(s):', deviceCount)
For a complete running example, see example.js.
The API is thin wrapper on top of the librltsdr API as found in the
rtl-sdr.h
file. All functions exposed by this module are named the same as their
librtlsdr counterparts, except for the rtlsdr_ prefix.
Only a few changes have been made to the return values and function arguments in order to make this suitable for JavaScript.
The following constants are exposed on the rtlsdr object:
TUNER_UNKNOWNTUNER_E4000TUNER_FC0012TUNER_FC0013TUNER_FC2580TUNER_R820TTUNER_R828Dcount = get_device_count()Return number of devices found.
name = get_device_name(index)Return name of device at index
error = get_device_usb_strings(index, manufact, product, serial)Get manufacturer, product and serial number from device at index.
Arguments:
index - Device indexmanufact - An zero filled Buffer with space for up to 256 bytes to
which the manufacturer name will be written (may be null)product - An zero filled Buffer with space for up to 256 bytes to
which the product name will be written (may be null)serial - An zero filled Buffer with space for up to 256 bytes to
which the serial number will be written (may be null)Returns 0 on success.
error = get_index_by_serial(serial)Get device index by USB serial string descriptor.
Returns 0 on success, -1 if name is null, -2 if no devices were
found at all, and -3 if devices were found, but nonee with mathcing
name.
device = open(index)Open device at index.
Returns a device handle that can be used as an argument to other functions.
error = close(device)Close device.
Arguments:
device - The device handle given by open()Returns 0 on success.
error = set_xtal_freq(device, rtl_freq, tuner_freq)Set crystal oscillator frequencies used for the RTL2832 and the tuner IC.
Usually both ICs use the same clock. Changing the clock may make sense if you are applying an external clock to the tuner or to compensate the frequency (and samplerate) error caused by the original (cheap) crystal.
NOTE: Call this function only if you fully understand the implications.
Arguments:
device - The device handle given by open()rtl_freq - Frequency value used to clock the RTL2832 in Hztuner_freq - Frequency value used to clock the tuner IC in HzReturns 0 on success.
error = get_xtal_freq(device, rtl_freq, tuner_freq)Get crystal oscillator frequencies used for the RTL2832 and the tuner IC.
Usually both ICs use the same clock.
Arguments:
device - The device handle given by open()rtl_freq - A 32 bit Buffer object to which a 32 bit unsigned
integer will be written with the frequency value used to clock the
RTL2832 in Hztuner_freq - A 32 bit Buffer object to which a 32 bit unsigned
integer will be written with the frequency value used to clock the
tuner IC in HzReturns 0 on success.
error = get_usb_strings(device, manufact, product, serial)Get USB device strings.
NOTE: The string arguments must provide space for up to 256 bytes.
Arguments:
device - The device handle given by open()manufact - An zero filled Buffer with space for up to 256 bytes to
which the manufacturer name will be written (may be null)product - An zero filled Buffer with space for up to 256 bytes to
which the product name will be written (may be null)serial - An zero filled Buffer with space for up to 256 bytes to
which the serial number will be written (may be null)Returns 0 on success
error = write_eeprom(device, data, offset, len)Write the device EEPROM.
Arguments:
device - The device handle given by open()data - Buffer of data to be writtenoffset - Address where the data should be writtenlen - Length of the dataReturns 0 on success, -1 if device handle is invalid, -2 if EEPROM
size is exceeded, or -3 if no EEPROM was found.
error = read_eeprom(device, data, offset, len)Read the device EEPROM.
Arguments:
device - The device handle given by open()data - Buffer where the data should be writtenoffset - Address where the data should be read fromlen - Length of the dataReturns 0 on success, -1 if device handle is invalid, -2 if EEPROM
size is exceeded, or -3 if no EEPROM was found.
error = set_center_freq(device, freq)Tune device to the given frequency.
Arguments:
freq - The center frequency to tune toReturns 0 on success.
freq = get_center_freq(device)Get actual frequency the device is tuned to.
Arguments:
device - The device handle given by open()Returns 0 on error, frequency in Hz otherwise.
error = set_freq_correction(device, ppm)Set the frequency correction value for the device.
Arguments:
device - The device handle given by open()ppm - Correction value in parts per million (ppm)Returns 0 on success.
ppm = get_freq_correction(device)Get actual frequency correction value of the device.
Arguments:
device - The device handle given by open()Returns correction value in parts per million (ppm).
type = get_tuner_type(device)Get the tuner type.
Arguments:
device - The device handle given by open()Returns TUNER_UNKNOWN on error, tuner type otherwise (see list of
tuner constants above).
numGains = get_tuner_gains(device, gains)Get a list of gains supported by the tuner.
NOTE: The gains argument must be preallocated by the caller. If null
is being given instead, the number of available gain values will be
returned.
Arguments:
device - The device handle given by open()gains - Empty array provided by the caller to which the list of gain
values will be written. In tenths of a dB, 115 means 11.5 dB. If using
a TypedArray, use an Int32Array with enough room to fill in the
available gains, e.g. size 100.Returns <= 0 on error, number of available (returned) gain values
otherwise.
error = set_tuner_gain(device, gain)Set the gain for the device.
Manual gain mode must be enabled for this to work.
Valid gain values (in tenths of a dB) for the E4000 tuner: -10, 15, 40, 65, 90, 115, 140, 165, 190, 215, 240, 290, 340, 420, 430, 450, 470, 490.
Valid gain values may be queried with get_tuner_gains function.
Arguments:
device - The device handle given by open()gain - In tenths of a dB, 115 means 11.5 dBReturns 0 on success.
gain = get_tuner_gain(device)Get actual gain the device is configured to.
Arguments:
device - The device handle given by open()Returns 0 on error, otherwise gain in tenths of a dB, 115 means 11.5
dB.
error = set_tuner_if_gain(device, stage, gain)Set the intermediate frequency gain for the device.
Arguments:
device - The device handle given by open()stage - Intermediate frequency gain stage number (1 to 6 for E4000)gain - In tenths of a dB, -30 means -3.0 dBReturns 0 on success.
error = set_tuner_gain_mode(device, stage, gain)Set the gain mode (automatic/manual) for the device. Manual gain mode must be enabled for the gain setter function to work.
Arguments:
device - The device handle given by open()manual - Gain mode, 1 means manual gain mode shall be enabled.Returns 0 on success.
error = set_sample_rate(device, samp_rate)Set the sample rate for the device, also selects the baseband filters according to the requested sample rate for tuners where this is possible.
Arguments:
device - The device handle given by open()samp_rate - The sample rate to be set, possible values are: 225001 -
300000 Hz and 900001 - 3200000 Hz. Sample loss is to be expected for
rates > 2400000Returns 0 on success, -EINVAL on invalid rate
hz = get_sample_rate(device)Get actual sample rate the device is configured to.
Arguments:
device - The device handle given by open()Returns 0 on error, sample rate in Hz otherwise.
error = set_testmode(device, test)Enable test mode that returns an 8 bit counter instead of the samples. The counter is generated inside the RTL2832.
Arguments:
device - The device handle given by open()test - Mode, 1 means enabled, 0 disabledReturns 0 on success.
error = set_agc_mode(device, digital)Enable or disable the internal digital AGC of the RTL2832.
Arguments:
device - The device handle given by open()digital - AGC mode, 1 means enabled, 0 disabledReturns 0 on success.
error = set_direct_sampling(device, on)Enable or disable the direct sampling mode. When enabled, the IF mode
of the RTL2832 is activated, and set_center_freq() will control the
IF-frequency of the DDC, which can be used to tune from 0 to 28.8 MHz
(xtal frequency of the RTL2832).
Arguments:
device - The device handle given by open()on - 0 means disabled, 1 I-ADC input enabled, 2 Q-ADC input enabledReturns 0 on success.
state = get_direct_sampling(device)Get state of the direct sampling mode
Arguments:
device - The device handle given by open()Returns -1 on error, 0 means disabled, 1 I-ADC input enabled, 2
Q-ADC input enabled.
error = set_offset_tuning(device, on)Enable or disable offset tuning for zero-IF tuners, which allows to avoid problems caused by the DC offset of the ADCs and 1/f noise.
Arguments:
device - The device handle given by open()on - 0 means disabled, 1 enabledReturns 0 on success.
state = get_offset_tuning(device)Get state of the offset tuning mode.
Arguments:
device - The device handle given by open()Returns -1 on error, 0 means disabled, 1 enabled
error = reset_buffer(device)Reset the internal buffer.
Arguments:
device - The device handle given by open()Returns 0 on success.
error = read_sync(device, buf, len, n_read)Read samples from the device synchronously.
NOTE: Make sure the buffer is big enough.
Arguments:
device - The device handle given by open()buf - The buffer to read intolen - The size of the buffern_read - A Buffer.alloc(4) object to which a 32 bit integer will
be written containing the size of the data that have been written to
bufReturns 0 on success.
read_async(device, on_data, on_end, buf_num, buf_len)Read samples from the device asynchronously. Data will be read until it
is being canceled using cancel_async()
Arguments:
device - The device handle given by open()on_data - Callback function to return received samples. The callback
will be called with a buffer as the first arguemnt and the size of the
buffer as the secondon_end - Callback function to be called once no more samples will be
readbuf_num - Optional buffer count, buf_num * buf_len = overall buffer
size set to 0 for default buffer count (15)buf_len - Optional buffer length, must be multiple of 512, should be
a multiple of 16384 (URB size), set to 0 for default buffer length
(16 * 32 * 512)Returns 0 on success.
error = cancel_async(device)Cancel all pending asynchronous operations on the device.
Arguments:
device - The device handle given by open()Returns 0 on success.
MIT