Category: Other

ADALM-PLUTO SDR: Unboxing and Initial Testing

The PlutoSDR (aka ADALM-PLUTO) is a new RX and TX capable SDR from Analog Devices who are a large semiconductor manufacturer. The PlutoSDR covers 325 – 3800 MHz, has a 12-bit ADC with a 61.44 MSPS sampling rate and 20 MHz bandwidth. It is also priced at the bargain price of only $99 USD over on Digikey, although it seems they only produced a small batch as at the moment they seem to be already sold out. This may also be a promotional price, with the normal price $149 USD as that is the price we see on the analog.com store. But even at $149 the value for what you get is very high.

A few months ago we preordered a PlutoSDR from the analog.com store, and it was received it a few days ago.

Unboxing

plutosdr_unbox1
plutosdr_unbox2
pluto_pcb2
pluto_pcb1

The unit comes in a nice professionally designed cardboard box. Inside is the unit itself, two small 4cm long whip antennas a short 15 cm SMA cable and USB cable. The PlutoSDR unit itself comes in a blue plastic box which measures 11.7 x 7.9 x 2.4 cm and weighs 114 g in total. Two SMA ports are available, one for RX and one for TX. At the other end are two LEDs, a USB port and a power only USB port.

The PCB itself looks to be designed nicely. On the PCB you can see the main AD9363 front end chip, which is actually a 2 x 2 transceiver chip. It supports a tunable channel bandwidth of up to 20 MHz. The other chip is the ZYNQ XC7Z010 which is an ‘All Programmable SoC’. This is an FPGA, processor and ADC for the unit.

Hardware

The PlutoSDR can tune from 325 to 3800 MHz. It has an ADC which can sample at up to 61.44 MSPS with a resolution of 12-bits. There is no TCXO used, so the frequency accuracy is only 25 PPM. Although the maximum sample rate is 61.44 MSPS, the front end AD9363 only has a maximum signal bandwidth of 20 MHz, so that limits the available bandwidth.

For TXing, a claimed TX power of up to 7 dBm is available which is comparable to the TX power of the HackRF.

The unit has no shielding on it via PCB cans or a metal box, so may pick up spurious signals. However, for the intended purpose of learning and testing, no shielding is fine.

Software

Unfortunately software for the PlutoSDR is quite lacking. At the moment there is only really support for MATLAB and GNURadio.

That’s quite understandable however as the PlutoSDR is designed and promoted as a ‘learning module’ or in other words a device for students to learn with. However, if software support for SDR#, HDSDR, SDR-Console, GQRX etc was available it would also make a great unit that could not only compete with the HackRF and LimeSDR SDRs, but also perhaps the Airspy and SDRplay RSP RX only units, at least for UHF applications above 325 MHz.

In a previous post in February we’ve seen on Twitter that Alex Csete (programmer of GQRX) has had his PlutoSDR running on GQRX, but it seems the current public release does not yet support the PlutoSDR (please correct me if i’m wrong!).

The documentation is mostly all available on the PlutSDR wiki. However documentation for setting the unit up with MATLAB and GNURadio, and examples for actually using it is also still quite poor. There is a quickstart guide, but this barely helped. Presumably once more units ship out the documentation will be enhanced. 

To install the PlutoSDR drivers on Linux we used the instructions kindly provided by xavier_505 in this Reddit thread. Once GNU Radio was installed, installation of the gr-iio driver was as simple as running the two lines provided in the thread.

Testing

We’ve given the PlutoSDR a few tests in Linux with GNURadio, and very quickly with the ADI IIO Oscillioscope software for Windows.

In GNU Radio the PlutoSDR source can be found under the “Industrial IO” heading in the block menu on the right, or simply by doing CTRL+F “Pluto”.

One important note is that when using the source you need to set the “Device URI” to ip:pluto.local. This feature presumably allows you to control multiple devices via the network, but for now we’re just using it locally. Also, this may have been a problem related to running Linux in VMWare, but PlutoSDR creates new “Wired Connection” in Linux and we had to always remember to set the network connection to the PlutoSDR using the the network selector in the Linux taskbar for the network to be able to see it.

First we tested a simple FFT and Waterfall sink using the PlutoSDR source. We set the sample rate to the maximum of 61.44 MSPS, and the RF bandwidth to 60M (although the max is 20 MHz). The demo ran well and we were able to see the 900 MHz GSM band. It seems the max sample rate is not used as the output is only 30 MHz, or perhaps it’s only one ADC.

Next we adapted a simple FM receiver from csetes GNU Radio examples by replacing the USRP source file with the PlutoSDR. After adjusting the decimation we were able to receive NBFM clearly.

Next we tried adapting a simple transmit test by creating a flowgraph that would transmit a .wav file in NBFM mode using the PlutoSDR Sink. Again this ran easily and we were able to verify the output in SDR# with an RTL-SDR. No harmonics were found (the one seen in the screenshot is a harmonic from the RTL-SDR).

Finally we tested using the PlutoSDR ADI IIO Oscilloscope software and were able to generate a FFT spectrum of the GSM band.

pluto_waterfall
pluto_rx_test
pluto_TX_test
pluto_ADI_IIO_Oscilloscope

Conclusion

This is a very nice SDR with good specs and a very very attractive price. However, it is mostly aimed at experimenters and students and you’ll need to be comfortable with exploring GNU Radio and/or MATLAB to actually use it. If you’re okay with that, then adapting various GNU Radio programs to use the PlutoSDR is quite easy.

In the future hopefully some programmers of general purpose receiving programs like SDR#/GQRX etc will release modules to support this unit too.

This is a good alternative to more expensive experimenter TX/RX SDR units like the HackRF and LimeSDR, although you do lose out on frequencies below 325 MHz.

ADALM-PLUTO SDR: Unboxing and Initial Testing

The PlutoSDR (aka ADALM-PLUTO) is a new RX and TX capable SDR from Analog Devices who are a large semiconductor manufacturer. The PlutoSDR covers 325 – 3800 MHz, has a 12-bit ADC with a 61.44 MSPS sampling rate and 20 MHz bandwidth. It is also priced at the bargain price of only $99 USD over on Digikey, although it seems they only produced a small batch as at the moment they seem to be already sold out. This may also be a promotional price, with the normal price $149 USD as that is the price we see on the analog.com store. But even at $149 the value for what you get is very high.

A few months ago we preordered a PlutoSDR from the analog.com store, and it was received it a few days ago.

Unboxing

plutosdr_unbox1
plutosdr_unbox2
pluto_pcb2
pluto_pcb1

The unit comes in a nice professionally designed cardboard box. Inside is the unit itself, two small 4cm long whip antennas a short 15 cm SMA cable and USB cable. The PlutoSDR unit itself comes in a blue plastic box which measures 11.7 x 7.9 x 2.4 cm and weighs 114 g in total. Two SMA ports are available, one for RX and one for TX. At the other end are two LEDs, a USB port and a power only USB port.

The PCB itself looks to be designed nicely. On the PCB you can see the main AD9363 front end chip, which is actually a 2 x 2 transceiver chip. It supports a tunable channel bandwidth of up to 20 MHz. The other chip is the ZYNQ XC7Z010 which is an ‘All Programmable SoC’. This is an FPGA, processor and ADC for the unit.

Hardware

The PlutoSDR can tune from 325 to 3800 MHz. It has an ADC which can sample at up to 61.44 MSPS with a resolution of 12-bits. There is no TCXO used, so the frequency accuracy is only 25 PPM. Although the maximum sample rate is 61.44 MSPS, the front end AD9363 only has a maximum signal bandwidth of 20 MHz, so that limits the available bandwidth.

For TXing, a claimed TX power of up to 7 dBm is available which is comparable to the TX power of the HackRF.

The unit has no shielding on it via PCB cans or a metal box, so may pick up spurious signals. However, for the intended purpose of learning and testing, no shielding is fine.

Software

Unfortunately software for the PlutoSDR is quite lacking. At the moment there is only really support for MATLAB and GNURadio.

That’s quite understandable however as the PlutoSDR is designed and promoted as a ‘learning module’ or in other words a device for students to learn with. However, if software support for SDR#, HDSDR, SDR-Console, GQRX etc was available it would also make a great unit that could not only compete with the HackRF and LimeSDR SDRs, but also perhaps the Airspy and SDRplay RSP RX only units, at least for UHF applications above 325 MHz.

In a previous post in February we’ve seen on Twitter that Alex Csete (programmer of GQRX) has had his PlutoSDR running on GQRX, but it seems the current public release does not yet support the PlutoSDR (please correct me if i’m wrong!).

The documentation is mostly all available on the PlutSDR wiki. However documentation for setting the unit up with MATLAB and GNURadio, and examples for actually using it is also still quite poor. There is a quickstart guide, but this barely helped. Presumably once more units ship out the documentation will be enhanced. 

To install the PlutoSDR drivers on Linux we used the instructions kindly provided by xavier_505 in this Reddit thread. Once GNU Radio was installed, installation of the gr-iio driver was as simple as running the two lines provided in the thread.

Testing

We’ve given the PlutoSDR a few tests in Linux with GNURadio, and very quickly with the ADI IIO Oscillioscope software for Windows.

In GNU Radio the PlutoSDR source can be found under the “Industrial IO” heading in the block menu on the right, or simply by doing CTRL+F “Pluto”.

One important note is that when using the source you need to set the “Device URI” to ip:pluto.local. This feature presumably allows you to control multiple devices via the network, but for now we’re just using it locally. Also, this may have been a problem related to running Linux in VMWare, but PlutoSDR creates new “Wired Connection” in Linux and we had to always remember to set the network connection to the PlutoSDR using the the network selector in the Linux taskbar for the network to be able to see it.

First we tested a simple FFT and Waterfall sink using the PlutoSDR source. We set the sample rate to the maximum of 61.44 MSPS, and the RF bandwidth to 60M (although the max is 20 MHz). The demo ran well and we were able to see the 900 MHz GSM band. It seems the max sample rate is not used as the output is only 30 MHz, or perhaps it’s only one ADC.

Next we adapted a simple FM receiver from csetes GNU Radio examples by replacing the USRP source file with the PlutoSDR. After adjusting the decimation we were able to receive NBFM clearly.

Next we tried adapting a simple transmit test by creating a flowgraph that would transmit a .wav file in NBFM mode using the PlutoSDR Sink. Again this ran easily and we were able to verify the output in SDR# with an RTL-SDR. No harmonics were found (the one seen in the screenshot is a harmonic from the RTL-SDR).

Finally we tested using the PlutoSDR ADI IIO Oscilloscope software and were able to generate a FFT spectrum of the GSM band.

pluto_waterfall
pluto_rx_test
pluto_TX_test
pluto_ADI_IIO_Oscilloscope

Conclusion

This is a very nice SDR with good specs and a very very attractive price. However, it is mostly aimed at experimenters and students and you’ll need to be comfortable with exploring GNU Radio and/or MATLAB to actually use it. If you’re okay with that, then adapting various GNU Radio programs to use the PlutoSDR is quite easy.

In the future hopefully some programmers of general purpose receiving programs like SDR#/GQRX etc will release modules to support this unit too.

This is a good alternative to more expensive experimenter TX/RX SDR units like the HackRF and LimeSDR, although you do lose out on frequencies below 325 MHz.

Listening to July’s Arecibo Observatory Ionospheric Heating Campaign

During July 24-31 the large Arecibo Radio Observatory in Puerto Rico (the big dish antenna that you may be familiar with from the movie ‘Contact’) ran an Ionospheric heating experiment which involves transmitting 600kW of net power up into the Ionosphere. This type of experiment is used for researching plasma turbulence in the ionosphere and upper atmosphere.

“The new Arecibo ionosphere HF heater nominally transmits 600 kW net power and has a unique Cassegrain dual-array antenna design that increases gain of three crossed dipoles for each band, using the signature 1000-foot spherical dish reflector,” explained Chris Fallen, KL3WX, a researcher at the University of Alaska-Fairbanks HAARP facility. He has reported that Arecibo would use 5.125 or 8.175 MHz, depending upon ionospheric conditions, but emphasized that these are estimates and frequencies may be adjusted slightly. On July 25, Arecibo was transmitting on 5.095 MHz.

Over on YouTube Mike L. used his SDRplay RSP1 together with our BCAM HPF to record some transmissions from the observatory.

Z33T’s Review of the ColibriNANO: $350 USD 10 kHz – 55 MHz SDR Dongle

Over on YouTube Mile Kokotov (Z33T) has uploaded his review of the ColibriNANO, which is a $350 USD 10 kHz – 55 MHz direct sampling SDR dongle built by Russian company Expert Electronics. It features a 14-bit direct sampling ADC which is then decimated into 16-bits at bandwidths of up to 3 MHz, or 24-bits at up to 768 kHz. This should give it excellent dynamic range preventing any sort of overloading.

In the video Mile gives the Colibri an excellent rating. In the video description he writes:

The Colibri-NANO USB stick is a powerful direct sampling SDR receiver with frequency range from 10 kHz to 55 MHz. ColibriNANO is not another cheap USB dongle found on e-bay. This high quality SDR receiver has been developed by Expert Electronics and has strongly and solidly build aluminum body, Electrostatic discharge (ESD) protection, USB 2.0 interface and a quality SMA antenna connector.

ColibriNANO has 14 bit Ananalog-To-Digital Converter, with a clock frequency of 122.88 MHz. Coverage is 10 kHz to 55 MHz, with low pass RF-filter on 55 MHz to protect from strong FM transmitters. The filter can be turned off so you can use the receiver in undersampling mode up to 500 MHz. In that case external filters and preamlifier (like the 2m filtered preamplifier from the same producer) is recommended for maximum results.. 

This excellent little SDR-receiver has nine IQ sample rates, from 48 kHz to 3 MHz so the frequency span on the spectrum window can be changed from 48 kHz up to 3 MHz.

There are no bandpass filters in the device, So one can think that a 14-bit Analog-To-Digital Converter may be subject to overload if you have powerful transmitters nearby. But the software has extensive RF gain control, so you should not have to worry too much. 
As I said before the Analog-to-Digital Converter in this wonderful SDR-receiver uses 14 Bit, and with decimation process results in an excellent 110 dB Blocking Dynamic Range. 

Another nice feature of the ColibriNANO SDR is the combined attenuator/pre-amplifier stage, which can be fine-adjusted in 0.5 dB steps from -31 to +6 dB. Together with the low noise floor and an excellent sensitivity, the result is a receiver with excellent large signal handling capabilities. The ColibriNANO is a perfect HF little SDR scanner which can be compare with much more expensive 
The Colibri-NANO can be operated directly attached to the computer of the user, or can be used remotely at a distant location. This is done with the freely available ExpertRemote software. 

At the location of the SDR a small computer is required (for example a Raspberry-Pi) and for the internet connection can be used a relatively slow internet link. This, for example, allows you to use the SDR receiver at some quiet location anywhere on the world.
Expert Electronics Software for the ColibriNANO allows you to use all the potential of the receiver: remote operation, synchronization with the transceiver, IQ channel bandwidth up to 3 MHz, control of the preamplifier and LPF and so on…

All mode for demodulation are supported. Here are Some of the software features:
– IQ output via Virtual Audio Cable
– Compatibility with any sound card installed on your PC for the audio output
– Synchronization with transceivers via CAT interface
– Remote operation with the ColibriNANO receiver 
– Special interface to control the CW Skimmer
– Screen resolution Supports FullHD and 4K monitors

And the important thing is that All new versions of the software are free!

To control the ColibriNANO via Internet you need freely available ExpertRemote system, based on the client-server connection. This system allows you to place the receiver and server in the remote location with low RF-noise but has the internet connection. This might be some remote village or place with no electrical interference and 3G/4G Internet (or any other connection type). 

Using the ExpertRemote system you can enjoy in clear noiseless reception from your phone, tablet, notebook or PC. Even simple antennas, placed in a “quiet” place, allows you to listen weak signals from the DX-stations better than in urban area filled with all kind of RF-noise.

Another feature of this system is that the receiver’s software can be synchronized with transceivers and be used as the panorama adapter with high resolution. In that way you can use the transceiver to transmit signals, and receive on your remotely located receiver via the ExpertRemote system. 

The ColibriNANO can be used with third party software like HDSDR etc.
You can find more information about this great 14 bit SDR-receiver on Expert electronics official website.
If you are interested in Radio technic and electronics fell free to visit my web-pages: www.qsl.net/z33t

This device appears that it will soon compete with the Airspy HF+ which is an upcoming SDR that claims similar performance for HF. We will work on comparing the two in a later review post.

Feedback Request: New RTL-SDR Product, Ideas and Interest Check

We are considering building a new multi-purpose RTL-SDR product. The idea is to make several difficult to achieve applications and projects much more accessible. We are looking to implement the following ideas:

  • 3x on-board coherent RTL-SDRs built into the PCB
    • 4x SMA inputs: 3x individual inputs, 1x common input (switched between the two). 
    • All RTL-SDRs connected to the same clock source – enables coherent experiments
    • All RTL-SDR feature sets and performance equivalent to RTL-SDR V3 or better
  • On-board noise source and directional coupler
    • Useful for correlation with rtl_coherent
    • Measure filter characteristics, and get rough SWR antenna readings.
  • Noise source able to be switched in and out via silicon switches
    • Useful with rtl_coherent and other coherent experiments for cross correlation timing correction. This allows for accurate direction finding.
  • Ability to mount onto a Raspberry Pi 3, and provide an ESD protected, buffered and filtered output for RpiTX transmissions. (a PCB plugin filter specific to the transmission frequency would need to be installed onto PCB to use this feature)
    • With a filter installed the board can be connected to an antenna and used with RpiTX for simple transmissions.
    • Go portable with an Raspberry Pi 3 compatible HDMI LCD screen and a battery pack. Possible HackRF portapack alternative.

Possible applications:

  • Multi-band RTL-SDR applications
    • One RTL-SDR receiving NOAA, one receiving ADS-B, one scanning the air band.
    • Easy trunk tracking with 2x RTL-SDR. Third RTL-SDR used for something else.
    • One streaming NOAA weather, one scheduled to receive NOAA/Meteor sats and weather balloons, one receiving Outernet weather updates.
  • Coherent applications
    • RF direction finding
    • Passive radar
    • Possible radio astronomy applications?
  • Noise source applications
    • Characterize filters
    • VSWR meter with directional coupler
  • Raspberry Pi mount applications
    • Replay attacks and security analysis of ISM band devices with RpiTX and an ISM band filter.
    • Transmitting WSPR with WSPRpi.
    • Portable if used with a small HDMI screen and battery pack.
    • Possible control of board via an Android app.
    • Similar applications to the HackRF Portapack idea.
    • Multi-band noise locator if a GPS is added to the Pi. e.g. See Tim Havens’ ‘Driveby’ concept.

The idea is still in the concept stages so we’re looking for any feedback from the community to see if this is even something that people would want.

Would a receiver board like this interest anyone? We would also work on providing basic ready to go software on a downloadable image file for the Raspberry Pi 3 so starting an app would be as easy as using a launcher. We would also provide various tutorials as well.

The target price would be $99 USD. If you think this is too much, please let us know what you would expect to pay in the comments.

Are there any additional features that anyone requests? Please let us know in the comments.

Would you pay $99 USD for a 3-input RTL-SDR coherent receiver with built in noise source, antenna switcher and filtered RpiTX output?

View Results

Loading ... Loading ...

Running Windows & x86 SDR Decoding Apps on the Raspberry Pi 3: Unitrunker, WinSTD-C, WXtoIMG, DSDPlus and more

There is a great advantage to running SDR decoder apps on a single board PC like a Raspberry Pi 3. For example instead of committing a whole PC to become a dedicated decoder, a cheap Pi 3 can be used instead. However, unfortunately many decoder apps are written for the x86 CPU architecture and/or Windows, making them impossible to run on ARM and/or primarily Linux devices like the Raspberry Pi 3.

That is unless you use an emulator combination like Eltechs Exagear and Wine. Exagear is an emulator that emulates an x86 environment on a device like a Raspberry Pi 3 which uses an ARM CPU. Wine is a Windows compatibility layer that allows you to run x86 Windows apps on an x86 Linux installation. So by combining Exagear together with Wine it is possible to run Windows apps on ARM Linux devices.

Exagear is not free (although there is a free trial). It currently costs $22.95 USD for a Pi 3 licence, and $16.95 USD for a Pi 2 licence and $11.45 for a Pi 1/Zero licence. They also have versions for Odroid, Cubieboard, BananaPi, Jetson and many other ARMv7 and ARMv8 devices like the super cheap and powerful Orange Pi’s. There are free alternatives out there like QEMU, however when we tested QEMU it was far too slow on the Pi 3 to even run notepad responsively, let alone a decoder. Exagear on the other hand seems to run apps at near native speeds, without much lag at all. So in this respect the price seems to be worth it.

We decided to test the Exagear + Wine combination on a Pi 3 and were successful in running a number of apps including Unitrunker, WinSTD-C, WXtoImg, DSDPlus, PC-HFDL, MultiPSK, Orbitron and Sondemonitor.

Trunking setup with Unitrunker on a Raspberry Pi 3

With Unitrunker we were able to set up a full trunk tracking system using two RTL-SDR dongles, rtl_fm, rtl_udp and a custom script to control rtl_udp.

Unitrunker running on a Raspberry Pi 3
Unitrunker running on a Raspberry Pi 3

In the future we may put up a full double checked tutorial with images, but for now a roughly written tutorial is presented below. The tutorial is fairly involved and assumes decent Linux experience. The tutorial starts from a fresh install of Raspbian.

The basic idea of operation is based around the fact that the RTL-SDR cannot be used directly within Wine (or so it seems). So the control signal audio is routed from rtl_fm running on one dongle into Unitrunker on Wine using alsa loopback. Then we use the old Unitrunker remote.dll method to generate a sdrsharptrunking.log file which is a text file that contains the current frequency that the voice receiver should tune to. A simple shell script continuously reads this file and extracts the frequency, and then commands an instance of rtl_udp running with the second dongle to tune to that frequency.

Continue reading

The BreadBoard RF103: A homemade 16-bit, 0 – 1800 MHz Software Defined Radio

Over on his blog IK1XPV has been writing about his experiments in trying to create a new SDR which he calls the ‘BreadBoard RF103’. His SDR is based on a FX3 SuperSpeed Explorer Kit which is a development platform that has an ARM9 processor on board, USB 3.0 connectivity and various expansion headers. Connected to that board is an LTC2217 16-bit ADC which can sample at up to 105 Msps. An R820T2 is used as the tuning chip to enable reception from 30 – 1800 MHz, and reception from 0 – 30 MHz is handled in direct sampling mode. The R820T2 is the same chip used on most RTL-SDR dongles, as well as on the higher end Airspy. It is a very good tuning chip, but it is held back by the 8-bit ADC on the RTL2832U chip. So the 16-bit ADC on the LTC2217 should be able to really show it off.

BreadBoard RF103 Block Diagram
BreadBoard RF103 Block Diagram

IK1XPV’s BreadBoard RF103 is currently running on HDSDR with 10 MHz of bandwidth. He writes that a modern and powerful PC with USB 3.0 is required to to handle all the data coming through. In the videos below he shows it receiving the FM band with what looks to be about 10 MHz of bandwidth.

So far the BreadBoard RF103 doesn’t seem planned to be a commercial device. The LTC2217 ADC is a $115 USD part, and the FX3 dev board is $49 USD. So while not a budget unit, it may still end up as as interesting SDR to home build and could contend with Airspy and SDRplay devices in the $100 – $300 USD range.

A Review of the KiwiSDR: 10 kHz – 30 MHz Wideband Network SDR

The KiwiSDR is a 14-bit wideband RX only HF software defined radio created by John Seamons (ZL/KF6VO) which has up to 32 MHz of bandwidth, so it can receive the entire 10 kHz – 30 MHz VLF/LF/MW/HF spectrum all at once. However, it is not a typical SDR as you do not connect the KiwiSDR directly to your PC. Instead the KiwiSDR is a cape (add on board) for the Beaglebone single board computing platform. If you’re unfamiliar with the Beaglebone, it is a small computing board that is similar to a Raspberry Pi. The KiwiSDR is designed to be a low cost standalone unit that runs 24/7, connects to your HF antenna and internet network, and shares your 10 kHz – 30 MHz reception over the internet with up to 4 simultaneous users.

The KiwiSDR
The KiwiSDR

The KiwiSDR kit retails for $299 USD (Amazon) (Direct from Seeed Studio), and with that price you get the KiwiSDR cape, a Beaglebone Green board, an enclosure, microSD card and a GPS antenna. If you already have a Beaglebone lying around, then you can purchase the KiwiSDR board only for $199 USD. 

Because the KiwiSDR is a network SDR, instead of connecting it to your PC it connects to your home internet network, allowing you to access it from any computing device via a web browser. Direct access to the SDR is not possible (actually it seems that it is, but it’s not easy to do), and all the computing is performed on the KiwiSDR’s on board FPGA and Beaglebone’s CPU before being sent to the network. Thus raw ADC or IQ data is never touched by your PC, your PC only sees the compressed audio and waterfall stream. So a powerful computer is not required to run the SDR. In fact, a mobile phone or tablet will do just fine.

In comparison, a $299 USD wideband non-networked SDR such as the LimeSDR uses a 12-bit ADC and can do up to 80 MHz of bandwidth over USB 3.0. But even on our relatively powerful PC (i7-6700 CPU, Geforce GTX 970 and 32 GB RAM) the LimeSDR can only get up to about 65 MHz on SDR-Console V3 before performance becomes too choppy.

But the real reason to purchase a KiwiSDR is that it is designed to be shared and accessed over the internet from anywhere in the world. You can connect to over 137 shared KiwiSDRs right now over at sdr.hu which is a site that indexes public KiwiSDRs. To achieve internet sharing, the KiwiSDR runs a modified version of András Retzler’s OpenWebRX software. OpenWebRX is similar to WebSDR, but is open source and freely available to download online. The standard OpenWebRX is also designed to support the RTL-SDR. Of course if you don’t want to share your receiver over the internet you don’t have to, and you could use it on your own local network only.

Some applications of the KiwiSDR might include things like: setting up a remote receiver in a good noise free location, helping hams give themselves propagation reports by accessing a remote KiwiSDR while they are TXing, listening to shortwave stations, monitoring WSPR or WEFAX channels, education, crowd sourced science experiments and more.

Continue reading

Talking to Ghosts with an RTL-SDR Dongle

Back in November of last year we posted about Doug Haber’s gqrx-ghostbox which is software that turns your RTL-SDR into an electronic voice phenomenon (EVP) tool, or in other words a ‘ghost box’ or ‘spirit box’. A ghost box is essentially a device that rapidly tunes between broadcast radio stations, creating mismashed audio of multiple stations. Paranormal researchers believe that such a tool can be used to communicate with ghosts or spirits. Over on Amazon commercial ghost boxes/spirit boxes seem to retail for anywhere from $70 USD to $140 USD so an RTL-SDR can be a budget way to get into paranormal research.

Over on her blog paranormal investigator shielaaliens has uploaded a post and video demonstrating an RTL-SDR based ghost box in action. Sheila actually doesn’t use the grqx-ghostbox software, but instead she just uses SDR# with a frequency scanner plugin set to rapidly scan through the broadcast band. In the video she asks the SDR# ghost box a few control questions such as “can you say kitty cat” and “can you say Nantucket”. In response the SDR# ghost box appears to respond with those exact words. Her Facebook post with the video can be found here.

Of course this might all sound pretty far fetched for most readers of this blog, but it is an application that the RTL-SDR is now being used for nonetheless!