pyhackrf

A Python wrappper for libhackrf

Description

I wanted something like pyrtldsr for the HackRF: a convenient python interface to handle calls to the libhackrf library. The closest thing I found was py-hackrf-ctypes, but it's about four years old and libhackrf has changed in that time. Also, I wanted a more direct copy of pyrtlsdr as I've used it before.

I have mashed together elements from pyrtlsdr and py-hackrf-ctypes to get started. Currently, you need to have the libhackrf.py file in the directory in which you are using it. Eventually I'll make it a nice package like pyrtlsdr.

This package is nowhere near complete but it implements read_samples, which is equivalent to the version found in pyrtlsdr.

Quick Example

To take samples and plot the power spectral density:

from libhackrf import *
from pylab import *     # for plotting

hackrf = HackRF()

hackrf.sample_rate = 20e6
hackrf.center_freq = 88.5e6

samples = hackrf.read_samples(2e6)

# use matplotlib to estimate and plot the PSD
psd(samples, NFFT=1024, Fs=hackrf.sample_rate/1e6, Fc=hackrf.center_freq/1e6)
xlabel('Frequency (MHz)')
ylabel('Relative power (dB)')
show()

More Example Use

To create a hackrf device:

from libhackrf import *

hackrf = HackRF()

If you have two HackRFs plugged in, you can open them with the device_index argument:

hackrf1 = HackRF(device_index = 0)
hackrf2 = HackRF(device_index = 1)

Callbacks

def my_callback(hackrf_transfer):
    c = hackrf_transfer.contents
    values = cast(c.buffer, POINTER(c_byte*c.buffer_length)).contents
    iq = bytes2iq(bytearray(values))

    return 0


# Start receiving...
hackrf.start_rx(my_callback)

# If you want to stop receiving...
hackrf.stop_rx()

Gains

There is a 14 dB amplifier at the front of the HackRF that you can turn on or off. The default is off.

The LNA gain setting applies to the IF signal. It can take values from 0 to 40 dB in 8 dB steps. The default value is 16 dB.

The VGA gain setting applies to the baseband signal. It can take values from 0 to 62 dB in 2 dB steps. The default value is 16 dB.

The LNA and VGA gains are set to the nearest step below the desired value. So if you try to set the LNA gain to 17-23 dB, the gain will be set to 16 dB. The same applies for the VGA gain; trying to set the gain to 27 dB will result in 26 dB.