HackRF Initial Review

Nytro · August 18, 2014

HackRF Initial Review

The HackRF One is a new software defined radio that has recently been shipped out to Kickstarter funders. It is a transmit and receive capable SDR with 8-Bit ADC, 10 MHz to 6 GHz operating range and up to 20 MHz of bandwidth. It can now be preordered for $299 USD. We just received ours from backing the Kickstarter and here’s a brief review of the product. We didn’t do any quantitative testing and this is just a first impressions review. So far we’ve only tested receive on Windows SDR#.

Unboxing

Inside the box is the HackRF unit in a quality protective plastic casing, a telescopic antenna and a USB cable. We show an RTL-SDR next to the HackRF for size comparison.

HackRF + Telescopic Antenna + USB Cable + Box (RTL-SDR Dongle Shown for Size Comparison)

Back of the box HackRF Windows SDR# Installation Process

Installation of the HackRF on Windows is very simple and is the same process as installing an RTL-SDR dongle. Assuming you have SDR# downloaded, simply plug in your HackRF into a USB port, open zadig in the SDR# folder, select the HackRF and click install driver. The HackRF is now ready to use with SDR#.

Initial Receive Review

We first tested the HackRF at its maximum bandwidth of 20 MHz in SDR#. Unfortunately at this sample rate the PC we used (Intel i5 750) could not keep up. The waterfall and audio were very choppy, even when the waterfall and spectrum analyser were turned off. After switching to the next lowest bandwidth of 16 MHz everything was fine. With the waterfall resolution set to 65536 the CPU usage was at around 45-50%.

It is very nice to have such a wide bandwidth at your disposal. However, the drawback is that with such a wide bandwidth it is very difficult to find a narrowband signal on the waterfall if the frequency is unknown. This might make things difficult for people new to signal browsing. Also, since the bandwidth is so wide the waterfall resolution when zoomed in is very poor making it very difficult to see a clear signal structure, but this is more a problem with SDR# rather than the HackRF.

The included antenna is good and made of a high quality build. There is a spring in the base of the antenna which may be an inductor, or may just be there for mechanical reasons. As the antenna screws directly into the HackRF body there is no place for a ground plane.

The HackRF has no front end filtering (preselectors) so there are many images of strong signals that show up at multiples of the selected sample rate. Most wideband SDRs are like this but these images are also not helped by the low 8 bit ADC resolution. Image rejection and sensitivity could be improved by using your own preselector front end like many people have done with the RTL-SDR. Overall reception sensitivity seems to be very similar to the RTL-SDR.

There are three gain settings available for the HackRF in SDR#. One is for the LNA Gain, one for VGA gain and the third is a check box for ‘Amp’. The LNA gain is the main gain that should be used and usually only a small amount of VGA gain is needed as VGA gain seems to just increase the noise the same amount as the signal. We’re not sure what ‘Amp’ is, but it seems to do something similar to ‘RTL AGC’ on the RTL-SDR.

We checked the PPM offset against a known signal and found that the offset was -12 ppm, which was pretty good. Only about 1 ppm of thermal drift was seen throughout the operation of the HackRF.

Overall the HackRF is a good product and is great for those who want the massive frequency range, wide bandwidth and transmit capability. But if you are interested in reception only and are looking for a wide bandwidth SDR upgrade to the RTL-SDR I would suggest waiting for the Airspy to be released. The advantage to the Airspy will be its 12-bit ADC and cheaper price. Airspy has entered production now and the first batch of 500 units should soon be available.

Here are some example wide band signals received with the HackRF.