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)
HackRF + Telescopic Antenna + USB Cable + Box (RTL-SDR Dongle Shown for Size Comparison)
Back of the box
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 which degrades the antennas performance somewhat.

The HackRF has no front end filtering (preselectors) so there are many images of strong signals (like pager 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. A strong interfering spike from the 10 MHz clock can be seen at every multiple of 10.

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. The ‘Amp’ button enables a front end amplifier which may be useful for very weak signals, but it should normally be turned off as it also amplifies noise and could potentially damage the HackRF if a very strong signal is nearby (Thanks to ‘Truth’ from the comments for pointing this out).

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.

The HackRF was able to receive all the expected signals across the advertised frequency range easily and was even able to go below the advertised 10 MHz to receive broadcast AM. At 10 MHz there was significant imaging from the broadcast AM band however so for HF use you may want to consider a bandstop or other filter.

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. (Note, this site is not affiliated with Airspy or HackRF in any way)

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

HackRF Receiving WFM
HackRF Receiving the entire WFM band
HackRF Receiving a DVB-T Signal
HackRF Receiving a DVB-T Signal
HackRF Receiving in the GSM Band
HackRF Receiving in the GSM Band
HackRF Possibly Receiving LTE?
HackRF Possibly Receiving LTE?
HackRF at 2.4 GHz - Must be WiFi
HackRF at 2.4 GHz – Must be WiFi?
HackRF Receiving AM Radio
HackRF Receiving the entire AM Radio Band

Here is another review by a YouTube user who focuses on HF reception

httpv://www.youtube.com/watch?v=sNwpQwn5awY

Here is an older review comparing the specs of the HackRF against the BladeRF and USRP B200.

6 comments

  1. Longjohn

    I don’t think the guy in the video really understands how these work compared to a soundcard based system like the Flex. Other than to initially pick a HF band you that want to work you really shouldn’t use a 20 Mhz wide ‘window’ to work a band that’s only a few hundred khz wide. If he had lowered the receive window bandwidth to a more reasonable width to fit the band of interest he likely wouldn’t be getting those images. It also illustrates the difference between 8 and 24 bit converters as well as high sample rate versus a much much lower sample rate (192 Khz for the Flex) )That’s why being able to switch sample rates ‘on the fly’ is so important. A more accurate comparison would be lowering the sample rate of the HackRF to be closer to the sample rate of the Flex.

    A 20 Mhz window is cool but it’s really a misuse of the technology to use it just because you can, and not because it’s necessary for the respective part of the spectrum you are working. Or there is a reason to use 10 or 20 Mhz wide window on the HF bands, for instance just to monitor the upper HF bands at once to be able to see when propagation conditions are right and they start to ‘open up’ to long range communication. Then break out the Flex (Which costs 10 times more than a HackRF and about 200 times more than an RTL dongle but that is the cost of high dynamic range) and go work them

  2. Longjohn

    The HackRF has the superior front end radio while the Airspy has the superior backend …. I’d sure like to ‘marry’ the two but since that’s likely not a realistic possibility I’ll probably end up getting both I have several homebrew HF SDR’s and a modified Delta 44 but it seems like every year there is less and less things on the HF bands that are interesting or useful. Even the ‘quality’ of Ham chatter seems to have dropped in recent years and let’s face it Contesting is pretty boring to just listen too (I can see the fun in participating but if there is a contest on a band I move to another)

    Who would have thought even 5 years ago that a under $20 TV Dongle would be a disruptive technology that would bring people back to radio in droves. The reigning King of technologies is still radio in one form or another, even computer technologies revolve around it. In 1995 very few computer engineers understood that they were going to have to start learning things like transmission line theory in order to design computers approaching gigahertz speeds and that radio would become the main medium of data transmission just like it has been for simple voice data for almost 100 years

    I just get a real kick out of watching computer geeks like Ossman and the folks over at HAK5 getting all excited discovering the wonderful world of RF because it not only is breathing new life into radio, it’s breathing new life into Hacking (Old School meaning) too … And that is always how the Technology advances to the next phase, computers and radio are where ‘amateurs’ (In any new technology everyone is an amateur) have always driven and expanded the envelope which is why they are so compatible together

  3. Frederik

    It looks like the image for the 2.4 ghz band shows bluetooth data. Wifi is usually at least 20 mhz wide and would cover the whole band.

    • Longjohn

      You also have to be aware that any strong signal in the received bandwidth will overload the ADC and potentially cause ‘blocking’ on the weak signals. Two approaches here to remedy that and often used in combination. One is of course narrowing the bandwidth so the offending strong signal is no longer ‘in the picture’ (And the cool thing about SDR is that’s literal) and the other is moving the received bandwidth around to do the same and use offset tuning for the desired weak signal. Since there are often more than one offending signals present a combination here often works best. Key to working the weak signals, especially with a dynamic range limited by 8 and even 12 bits (In practice your true dynamic range is closer to 6 and 10 bits …. physics, it’s a cruel master) is getting the strong signals out of the picture so they can’t overload the ADC and getting the signal up high enough to overcome the inaccuracy and noise in the 2 LSB’s of the converter. (Most modern audio ADC’s fill these bits intentionally with noise and then throws them away after conversion which is why you can’t even get 18 bits of true dynamic range from a 24 bit ADC ‘in the real world’) Generally as a rule of thumb I subtract 2 bits and that gives me a more accurate idea of it’s Real World performance …. And why you have to use 18 and 24 bit ADC’s to get recordings with a true 16 bits (98 db) of dynamic range (16 bit CD’s have less than 15 bits of dynamic range in the Real World)

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