Category: Airspy

Our Review of the Airspy HF+: Compared against ColibriNANO, Airspy Mini, RSP2

Over the last few months we’ve been posting and getting excited about the Airspy HF+, an upcoming high dynamic range HF/VHF receiver designed for DXing. The Airspy team were kind enough to supply us with an early pre-production unit for review.

Long story short, the Airspy HF+ is probably one of the best low cost SDRs we’ve seen for DXing or weak signal reception out there. So far few details on the availability of the HF+ have been released, but we’re aware that preorders are due to start soon, and the target price is expected to be $149 USD from iTead Studio in China. 

What follows is the full review and comparisons against other similarly priced SDRs. The Airspy team want us and readers to understand that our review unit is a pre-production model, and apparently already the matching and thus SNR has already been improved by about 2-4 dBs, so the sound samples we provide in the review below should sound even better with the newer revision.

Disclaimer: We received the HF+ for free in exchange for an honest review, but are not affiliated with Airspy. We’ve been in contact with the Airspy team who have helped clarify some points about the architecture and technology used in the design.

Introduction

The Airspy HF+ is designed to be a HF/VHF specialist receiver with a frequency range of DC to 31 MHz, and then 60 to 260 MHz. It has a maximum bandwidth of 768 kHz. So the question is then, why would you consider buying this over something like the regular Airspy R2/Mini or an SDRplay RSP2 which both have larger frequency ranges and bandwidths? You would buy the Airspy HF+ because has been designed with DXing and weak signal reception in mind. Basically the main idea behind the HF+ is to design it so that it will never overload when in the presence of really strong signals. Combined with it’s high sensitivity, weak or DX signals should come in much clearer than on the other radios especially if you have strong blocking signals like broadcast AM/FM around.

Aside: What is overloading, intermodulation and dynamic range?

Basically strong signals can cause weak signals to be drowned out, making them not receivable, even though they’re there at your antenna. This is called overloading or saturation. Intermodulation occurs when the SDR overloads and results in images of unwanted signals showing up all over the spectrum.

A simple analogy is to think about what happens when you are trying to drive, but there is sunstrike. The road is very hard to see because the sun is so bright and right in your eyes. The human eye does not have enough “dynamic range” to handle the situation of sunstrike. Dynamic range is a measure of how well a radio (eye) can handle strong (bright) and weak (dark) signals at the same time. The same analogy applies to radios which can struggle to ‘see’ weak signals if there is a very strong signal nearby on the frequency spectrum. There are a few ways to solve this:

  • Filtering: Block the strong signals that you don’t want using LC filters.
    • Eye analogy: using your sun visor to block the sun.
  • Attenuation: Reduce the strength of all signals.
    • Eye analogy: using sunglasses or squint.
  • Increase dynamic range: Get a better SDR with better design/technology and more bits in the ADC.
    • Eye analogy: upgrade your eyes.

Technology and Architecture

The HF+ uses a typical Filter->Tuner ->ADC architecture. So it is not a direct sampling receiver like most of the more expensive SDRs. Direct sampling receivers directly sample the analogue spectrum, without the need for a tuner so they avoid losses and the intermodulation problems that usually come from the mixing stages. But there are some major cutting edge technology differences in the HF+ architecture that should make its performance even better than direct sampling receivers.

Tuner: The tuner on the HF+ is one of the first to use a “Polyphase Harmonic Rejection” architecture. Essentially this means that harmonics produced in the mixing stages are naturally rejected, making the front end filtering requirements much more relaxed. So unlike the tuners used in other SDRs, this one is extremely unlikely overload in the mixing stage.

An additional benefit to this architecture is that the mixer is very low loss, so the LNA in the tuner only needs to use low gain, giving it a very high IIP3 value. So the first LNA which is typically another point of saturation and imermodulation, is very unlikely to saturate in the HF+ design. Most of the amplification only occurs after the mixing stage with the filtered narrowband output of the tuner.

Analogue to Digital Converter (ADC): The ADC is 16-bits and uses a “Sigma Delta” (ΣΔ) design. Basically a Sigma Delta ADC has a natural filtering ability due to its narrowband nature. Instead of seeing say a 30 MHz signal, it only sees 1 – 2 MHz, thus increasing dynamic range and reducing the likelihood of out of band overload.

Digital Down-Converter (DDC): Then after the ADC is a DDC which decimates the output from the ADC, increasing the effective number of bits. The more bits the larger the resolution of the digitized RF signal, so weak signals are less likely to be lost when converted from analogue to digital.

The HF+ Block Diagram
The HF+ Block Diagram

So the block diagram flow goes like this:

A weakly filtered signal enters the tuner, is weakly amplified by the tuner LNA, mixed down to baseband and filtered to 1-2 MHz. It is then amplified and sampled with the sigma delta ADC into 16-bits. The DDC decimates the output into 18-bits which is then sent to the microcontroller and PC via USB.

The Airspy team also compiled this comparison chart for us to understand the differences in architecture between the current SDRs on the market (click to enlarge). This shows that the HF+ is a different type of design compared to other SDRs. Generally the best SDRs out the market right now are direct sampling receivers with many filter banks. The HF+ approaches the problem in a different way, and according to the specs seems to match or better the performance of heavily filtered direct sampling receivers.

Performance from the Airspy HF+ product page is stated as:

  • -141.0 dBm (0.02 µV / 50 ohms) MDS Typ. at 500Hz bandwidth in HF
  • -141.5 dBm MDS Typ. at 500Hz bandwidth in FM Broadcast Band (60 – 108 MHz)
  • -139.5 dBm MDS Typ. at 500Hz bandwidth in VHF Aviation Band (118 – 136 MHz)
  • -139 dBm MDS Typ. at 500Hz bandwidth in VHF Commercial Band (136 – 174 MHz)
  • -138 dBm MDS Typ. at 500Hz bandwidth in the upper VHF Band (> 174 MHz)
  • +26 dBm IIP3 on HF at maximum gain
  • +13 dBm IIP3 on VHF at maximum gain
  • 110 dB blocking dynamic range in HF
  • 95 dB blocking dynamic range in VHF

Continue reading

New Airspy HF+ Pics and Sensitivity Test

The Airspy HF+ is an upcoming product from the Airspy team that is intended to be a high performance HF/VHF receiver at a low price. Its frequency range will be DC to 31 MHz, and 60 to 260 MHz and the bandwidth will be about 660 kHz. So why choose the HF+ over the Airspy R2, Mini or SDRplay which all have larger frequency ranges and bandwidths? It seems the focus of the HF+ is to be an extremely high dynamic range receiver. This means that strong signals should almost never overload the receiver making it very good for DXing weak signals (listening to weak signals from very far away). On other receivers once you turn the gain up strong signals can block reception of the weaker ones.

Recently we saw the release of some of the first 3D renderings of the product. Now finally we have a photo of the actual PCB which is shown below. The RF sensitive innards are hidden away within a shielding can, but we know from the product page that inside are the switches, filters, tuner, ADC and 18-bit DDC.

The Airspy HF+ PCB
The Airspy HF+ PCB

Also, over on Twitter, @lambdaprog, lead creator of SDR# and of the Airspy HF+ has uploaded some sensitivity tests. It seems that sensitivity will be at least -136 dBM at 20 meters, as a -136 dBm signal still comes in with 21 dB of SNR. Similar sensitivity results are obtained on the FM Band.


The Airspy team have sent us a sample unit from an early manufacturing test and we hope to have a full review available a few weeks after we receive it.

SDR-Console V3 Latest Update: Signal History & Receiver Panes

SDR-Console is a popular RTL-SDR compatible multi purpose SDR software package which is similar to programs like SDR#, HDSDR and SDRuno. Currently SDR-Console V2 is the stable version and SDR-Console V3 is in a beta state. A few days ago SDR-Console V3 Preview 6 was released. It comes with some very interesting new features including a built in Airspy server, a recording scheduler, a new feature called signal history and a new receivers pane.

Over on his blog Nils Schiffhauer (DK8OK) has been reviewing the new release of SDR-Conosle V3 and writes the following information about some of the new features:

  • “Signal History” takes the signal strength of the given bandwidth each 50 milliseconds, which can be saved in a CSV file. It is also shown in three different speeds on a display.
  • “Receivers’ Pane” shows up to six combos of spectrum/spectrogram of the complete up to 24 parallel demodulators (they additionally can be shown in the Matrix, as in former versions).

“Signal History” offers many applications, to name just three:

  • analyze fading and its structure with an unsurpassed time resolution of 50 ms
  • document fade-in and fade out
  • measure signal-to-noise ratio of signals

In addition Nils has also uploaded a very useful 19 page PDF where he writes step by step instructions and shows numerous examples of the new signal history tool.

DK8OK's SDR-Console V3 P6 Screenshot. Showing multiple receiver panes and the new signal history feature.
DK8OK’s SDR-Console V3 P6 Screenshot. Showing multiple receiver panes and the new signal history feature.
DK8OK's screenshot of the signal history toolbox.
DK8OK’s screenshot of the signal history toolbox.

First Renderings of the Airspy HF+ Revealed

Back in February of this year we first heard about the Airspy HF+, which is an upcoming product from the Airspy team that is intended to be a high performance HF receiver at a low price. Over on the Airspy HF+ website the first (rendered) image of the unit has recently been released. We’ve also managed to get some additional renderings from the Airspy team which we show in the image slider below.

The enclosure is CNC carved aluminum with two SMA ports on one side, and a USB port on the rear. Since the HF+ actually has the capability to tune up to 260 MHz it uses two SMA inputs, one for an HF antenna and one for a VHF antenna. Inside the RF circuit is shielded again with a shielding can to protect it from USB noise.

The tweet below also appears to show some grounding improvements made to reduce USB noise.

Other recent tweets from prog (the creator of the Airspy HF+) indicate that the hardware is ready, and show that streaming from with SpyServer from a RPi3 is functional. Hopefully we should be seeing this unit release for sale soon.

Our Review of the Airspy HF+: Compared against ColibriNANO, Airspy Mini, RSP2

Over the last few months we’ve been posting and getting excited about the Airspy HF+, an upcoming high dynamic range HF/VHF receiver designed for DXing. The Airspy team were kind enough to supply us with an early pre-production unit for review.

Long story short, the Airspy HF+ is probably one of the best low cost SDRs we’ve seen for DXing or weak signal reception out there. So far few details on the availability of the HF+ have been released, but we’re aware that preorders are due to start soon, and the target price is expected to be $149 USD from iTead Studio in China. 

What follows is the full review and comparisons against other similarly priced SDRs. The Airspy team want us and readers to understand that our review unit is a pre-production model, and apparently already the matching and thus SNR has already been improved by about 2-4 dBs, so the sound samples we provide in the review below should sound even better with the newer revision.

Disclaimer: We received the HF+ for free in exchange for an honest review, but are not affiliated with Airspy. We’ve been in contact with the Airspy team who have helped clarify some points about the architecture and technology used in the design.

Introduction

The Airspy HF+ is designed to be a HF/VHF specialist receiver with a frequency range of DC to 31 MHz, and then 60 to 260 MHz. It has a maximum bandwidth of 768 kHz. So the question is then, why would you consider buying this over something like the regular Airspy R2/Mini or an SDRplay RSP2 which both have larger frequency ranges and bandwidths? You would buy the Airspy HF+ because has been designed with DXing and weak signal reception in mind. Basically the main idea behind the HF+ is to design it so that it will never overload when in the presence of really strong signals. Combined with it’s high sensitivity, weak or DX signals should come in much clearer than on the other radios especially if you have strong blocking signals like broadcast AM/FM around.

Aside: What is overloading, intermodulation and dynamic range?

Basically strong signals can cause weak signals to be drowned out, making them not receivable, even though they’re there at your antenna. This is called overloading or saturation. Intermodulation occurs when the SDR overloads and results in images of unwanted signals showing up all over the spectrum.

A simple analogy is to think about what happens when you are trying to drive, but there is sunstrike. The road is very hard to see because the sun is so bright and right in your eyes. The human eye does not have enough “dynamic range” to handle the situation of sunstrike. Dynamic range is a measure of how well a radio (eye) can handle strong (bright) and weak (dark) signals at the same time. The same analogy applies to radios which can struggle to ‘see’ weak signals if there is a very strong signal nearby on the frequency spectrum. There are a few ways to solve this:

  • Filtering: Block the strong signals that you don’t want using LC filters.
    • Eye analogy: using your sun visor to block the sun.
  • Attenuation: Reduce the strength of all signals.
    • Eye analogy: using sunglasses or squint.
  • Increase dynamic range: Get a better SDR with better design/technology and more bits in the ADC.
    • Eye analogy: upgrade your eyes.

Technology and Architecture

The HF+ uses a typical Filter->Tuner ->ADC architecture. So it is not a direct sampling receiver like most of the more expensive SDRs. Direct sampling receivers directly sample the analogue spectrum, without the need for a tuner so they avoid losses and the intermodulation problems that usually come from the mixing stages. But there are some major cutting edge technology differences in the HF+ architecture that should make its performance even better than direct sampling receivers.

Tuner: The tuner on the HF+ is one of the first to use a “Polyphase Harmonic Rejection” architecture. Essentially this means that harmonics produced in the mixing stages are naturally rejected, making the front end filtering requirements much more relaxed. So unlike the tuners used in other SDRs, this one is extremely unlikely overload in the mixing stage.

An additional benefit to this architecture is that the mixer is very low loss, so the LNA in the tuner only needs to use low gain, giving it a very high IIP3 value. So the first LNA which is typically another point of saturation and imermodulation, is very unlikely to saturate in the HF+ design. Most of the amplification only occurs after the mixing stage with the filtered narrowband output of the tuner.

Analogue to Digital Converter (ADC): The ADC is 16-bits and uses a “Sigma Delta” (ΣΔ) design. Basically a Sigma Delta ADC has a natural filtering ability due to its narrowband nature. Instead of seeing say a 30 MHz signal, it only sees 1 – 2 MHz, thus increasing dynamic range and reducing the likelihood of out of band overload.

Digital Down-Converter (DDC): Then after the ADC is a DDC which decimates the output from the ADC, increasing the effective number of bits. The more bits the larger the resolution of the digitized RF signal, so weak signals are less likely to be lost when converted from analogue to digital.

The HF+ Block Diagram
The HF+ Block Diagram

So the block diagram flow goes like this:

A weakly filtered signal enters the tuner, is weakly amplified by the tuner LNA, mixed down to baseband and filtered to 1-2 MHz. It is then amplified and sampled with the sigma delta ADC into 16-bits. The DDC decimates the output into 18-bits which is then sent to the microcontroller and PC via USB.

The Airspy team also compiled this comparison chart for us to understand the differences in architecture between the current SDRs on the market (click to enlarge). This shows that the HF+ is a different type of design compared to other SDRs. Generally the best SDRs out the market right now are direct sampling receivers with many filter banks. The HF+ approaches the problem in a different way, and according to the specs seems to match or better the performance of heavily filtered direct sampling receivers.

Performance from the Airspy HF+ product page is stated as:

  • -141.0 dBm (0.02 µV / 50 ohms) MDS Typ. at 500Hz bandwidth in HF
  • -141.5 dBm MDS Typ. at 500Hz bandwidth in FM Broadcast Band (60 – 108 MHz)
  • -139.5 dBm MDS Typ. at 500Hz bandwidth in VHF Aviation Band (118 – 136 MHz)
  • -139 dBm MDS Typ. at 500Hz bandwidth in VHF Commercial Band (136 – 174 MHz)
  • -138 dBm MDS Typ. at 500Hz bandwidth in the upper VHF Band (> 174 MHz)
  • +26 dBm IIP3 on HF at maximum gain
  • +13 dBm IIP3 on VHF at maximum gain
  • 110 dB blocking dynamic range in HF
  • 95 dB blocking dynamic range in VHF

Continue reading

New Airspy HF+ Pics and Sensitivity Test

The Airspy HF+ is an upcoming product from the Airspy team that is intended to be a high performance HF/VHF receiver at a low price. Its frequency range will be DC to 31 MHz, and 60 to 260 MHz and the bandwidth will be about 660 kHz. So why choose the HF+ over the Airspy R2, Mini or SDRplay which all have larger frequency ranges and bandwidths? It seems the focus of the HF+ is to be an extremely high dynamic range receiver. This means that strong signals should almost never overload the receiver making it very good for DXing weak signals (listening to weak signals from very far away). On other receivers once you turn the gain up strong signals can block reception of the weaker ones.

Recently we saw the release of some of the first 3D renderings of the product. Now finally we have a photo of the actual PCB which is shown below. The RF sensitive innards are hidden away within a shielding can, but we know from the product page that inside are the switches, filters, tuner, ADC and 18-bit DDC.

The Airspy HF+ PCB
The Airspy HF+ PCB

Also, over on Twitter, @lambdaprog, lead creator of SDR# and of the Airspy HF+ has uploaded some sensitivity tests. It seems that sensitivity will be at least -136 dBM at 20 meters, as a -136 dBm signal still comes in with 21 dB of SNR. Similar sensitivity results are obtained on the FM Band.


The Airspy team have sent us a sample unit from an early manufacturing test and we hope to have a full review available a few weeks after we receive it.

SDR-Console V3 Latest Update: Signal History & Receiver Panes

SDR-Console is a popular RTL-SDR compatible multi purpose SDR software package which is similar to programs like SDR#, HDSDR and SDRuno. Currently SDR-Console V2 is the stable version and SDR-Console V3 is in a beta state. A few days ago SDR-Console V3 Preview 6 was released. It comes with some very interesting new features including a built in Airspy server, a recording scheduler, a new feature called signal history and a new receivers pane.

Over on his blog Nils Schiffhauer (DK8OK) has been reviewing the new release of SDR-Conosle V3 and writes the following information about some of the new features:

  • “Signal History” takes the signal strength of the given bandwidth each 50 milliseconds, which can be saved in a CSV file. It is also shown in three different speeds on a display.
  • “Receivers’ Pane” shows up to six combos of spectrum/spectrogram of the complete up to 24 parallel demodulators (they additionally can be shown in the Matrix, as in former versions).

“Signal History” offers many applications, to name just three:

  • analyze fading and its structure with an unsurpassed time resolution of 50 ms
  • document fade-in and fade out
  • measure signal-to-noise ratio of signals

In addition Nils has also uploaded a very useful 19 page PDF where he writes step by step instructions and shows numerous examples of the new signal history tool.

DK8OK's SDR-Console V3 P6 Screenshot. Showing multiple receiver panes and the new signal history feature.
DK8OK’s SDR-Console V3 P6 Screenshot. Showing multiple receiver panes and the new signal history feature.
DK8OK's screenshot of the signal history toolbox.
DK8OK’s screenshot of the signal history toolbox.

First Renderings of the Airspy HF+ Revealed

Back in February of this year we first heard about the Airspy HF+, which is an upcoming product from the Airspy team that is intended to be a high performance HF receiver at a low price. Over on the Airspy HF+ website the first (rendered) image of the unit has recently been released. We’ve also managed to get some additional renderings from the Airspy team which we show in the image slider below.

The enclosure is CNC carved aluminum with two SMA ports on one side, and a USB port on the rear. Since the HF+ actually has the capability to tune up to 260 MHz it uses two SMA inputs, one for an HF antenna and one for a VHF antenna. Inside the RF circuit is shielded again with a shielding can to protect it from USB noise.

The tweet below also appears to show some grounding improvements made to reduce USB noise.

Other recent tweets from prog (the creator of the Airspy HF+) indicate that the hardware is ready, and show that streaming from with SpyServer from a RPi3 is functional. Hopefully we should be seeing this unit release for sale soon.

A Review of the SpyVerter R2

The SpyVerter is a high performance upconverter that enables HF reception on SDR’s that aren’t able to tune directly to HF frequencies. Like any upconverter it works by converting those lower HF frequencies ‘up’ into a higher frequency range that is actually receivable by the SDR.

Back in December 2015 when the SpyVerter first came out we reviewed the unit and found that it was probably the best and highest value upconverter on the market. It was priced at a similar or cheaper price to competitors, came in a metal enclosure and had excellent performance. The main reason for its high performance is due to the architecture. While most upconverters on the market like the ham-it-up use an ADE-1 double balanced mixer component, the SpyVerter instead uses an H-mode mixer design. This design is harder to engineer, but it provides better dynamic range meaning that strong signals are less likely to overload the upconverter.

The SpyVerter was recently given a refresh, and the SpyVerter R2 is now available. The changes are small and are mostly centered around the clock. The oscillator is now a 24 MHz 0.5 PPM TCXO, run through a SI5351 clock generator to produce the 120 MHz upconversion frequency. A new onboard microcontroller programs the SI5351 on power up.

This change in clock design also now allows you to connect a 10 MHz reference frequency if ultra stable, or phase coherent frequency operation is required. A u.FL connector is provided next to the output SMA connector on the PCB for connecting a 10 MHz reference. Unfortunately there is no breakout hole in the metal enclosure, meaning that you’ll need to drill your own hole in the enclosure to get the u.FL clock cable out. Few people will need this feature however, as thanks to the 0.5 PPM TCXO stock frequency stability is now excellent.

The new design also uses less power, only drawing 10 mA of current compared to 47 mA in the SpyVerter R1. It also has 12 dB lower local oscillator leakage meaning that the gains might be able to be pushed slightly higher without overload. Once again, just like with the SpyVerter R1 the R2 is also powered via the bias tee on the Airspy, and so is compatible with the bias tee on our RTL-SDR V3 dongles.

There’s also an interesting mod that can be performed with the SpyVerter R2. The LO frequency can be modded to run at 58 MHz instead of 120 MHz. 58 MHz is just low enough to avoid the broadcast FM band, and the lower frequency allows the switches used in the H-mode design to run at a lower frequency. This results in an insertion loss better by about 3 dB’s and less LO leakage meaning that the RF gains can be pushed higher. The main disadvantage to this mod is that the lowest input frequency will only be 28 MHz.  The mod details don’t seem to be published yet, but we’ll update this post once they are.

The cost of the SpyVerter R2 remains the same as before at $49 USD. Compared to the Ham-It-Up v1.3 which costs $41.95 USD and does not come with an enclosure or TCXO, the SpyVerter still seems to be the best value. Currently you can buy one internationally from iTead who ship from China, at Airspy.us for US customers, and there are several European distributors linked on the Airspy website.

Disclaimer: The SpyVerter R2 was sent by the Airspy team to us for free in exchange for an honest review.

SpyServer 2.0 Released: More Efficient Streaming for Airspy and RTL-SDR

Back in March the team behind the Airspy SDR and SDRSharp software released the SpyServer, a piece of software that allows you to stream radio data from a remote Airspy receiver over a network. Then later in April they added full support for the RTL-SDR dongle as well.

This Easter the Airspy team have released SpyServer 2.0, which improves the streaming efficiency significantly (changelog). Now the full 8 MHz bandwidth of the Airspy should be easily streamable over an internet connection. With SpyServer 1.0 it was difficult to make use of the full bandwidth of the Airspy because the network data usage was very high, since it was streaming the full raw IQ data for the sampling rate/bandwidth selected. In SpyServer 2.0 the server does not stream the full raw data, and instead only streams the wideband FFT data (for displaying the waterfall and FFT graph), and the raw data from the currently selected IF bandwidth. Of course the full IQ data can still be streamed if desired by selecting the ‘Use full IQ’ checkbox.

This new efficiency means that WFM uses only about 1.3 MB/s, and narrow band modes like NFM/AM/SSB only use about 120 kB/s of network data which is easily achievable over a local network and internet. This data usage is almost independent of the sampling rate/bandwidth selected so you can stream the full 8 MHz offered by the Airspy without trouble. Normally streaming the full raw data for 8 MHz would use about 40 MB/s, which is difficult to achieve over a local network, and impossible over the internet.

We tested the new SpyServer over our local network and were able to stream the full 8 MHz of the Airspy with no problems. With the RTL-SDR we were also able to stream 2.4 MHz without issue. WFM and NFM modes worked clearly and no skips or significant lag was noticed over a local WiFi N connection. Hopefully in the future SpyServer will be developed further to enable compressed audio streaming as well for even lower network data usage.

SpyServer WFM Reception. About 1.3 MB/s network usage.
SpyServer WFM Reception. About 1.3 MB/s network usage.
SpyServer NFM Reception. About 120 kB/s network usage.
SpyServer NFM Reception. About 120 kB/s network usage.

Some Operational Notes:

  • To run SpyServer on Windows simply double click on spyserver.exe. On Linux extract “spyserver_linux_x86” and the config file, and then run “sudo chmod +x spyserver_linux_x86”. Then run it with “./spyserver_linux_x86”.
  • Connect to it on the remote PC in SDR# using the servers IP address which can be found by typing “ipconfig /all” in Windows command prompt, or “ifconfig” on Linux.
  • To select between using the Airspy and RTL-SDR for the SpyServer you will need to edit the spyserver.config file with a text editor and edit the “device_type” string.
  • SpyServer runs on Windows/Linux as well as small embedded computers such as Raspberry Pi’s and Odroids. Download the Raspberry Pi and Odroid servers separately from SDR# at http://airspy.com/download.
  • SpyServer is NOT compatible with software that expects an rtl_tcp server such as SDRTouch.

We have also seen Lucas Teske of the OpenSatellite project use the SpyServer for streaming a GOES16 downlink over a network connection with an Odroid C2. He writes that soon the OpenSatellite project software will directly support SpyServer.

DK8OK Review of the Airspy and SpyVerter

Recently DK8OK wrote in to us and wanted to share his latest review of the Airspy and SpyVerter combo (pdf). His review focuses on HF usage and he shows various examples of HF signals that he has received with the Airspy+SV such as the CHU time station, STANAG, DRM, ALE, HFFAX, VOLMET and HFDL. He also shows some tricks for optimizing HF reception, a tutorial on performing multi-channel audio recording and decoding in SDR-Console, a tutorial on playing and analyzing recorded files as well as some examples of weak signal reception.

Overall DK8OK praises the Airspy+SV combo citing it’s excellent dynamic range as one of the reasons it performs so well.

We should note that for prospective buyers, the Airspy team is currently working on a new complimentary solution for HF monitoring called the Airspy HF+. This will have extremely high dynamic range (even higher than the Airspy+SV combo), but it will have a smaller bandwidth. So the Airspy+SV combo will still be the best for monitoring a wide 9 MHz chunk of the HF band, whilst the HF+ will be the best for getting into those very hard to receive signals.

Update: The paper is now also available in French.

Multi-channel decoding in SDR-Console with the Airspy+SypVerter
Multi-channel decoding in SDR-Console with the Airspy+SpyVerter

SDRSharp SpyServer Now Supports the RTL-SDR

About a month ago the Airspy and SDRSharp development team released their new ‘SpyServer’ software. SpyServer is a streaming server for Airspy devices, which allows them to be used over a network connection. It is somewhat similar to rtl_tcp which is familiar to RTL-SDR users, although unlike rtl_tcp, SpyServer uses a multiclient architecture which allows several clients to connect to the server at the same time with each being able to choose individual bandwidth settings.

Today SpyServer was updated (changelog), and it now also supports the RTL-SDR dongle. The software can be found in the latest version of SDR# from www.airspy.com. The Airspy download contains the SpyServer for Windows and Linux, and the Raspberry Pi and Odroid server is available here.

To use SpyServer with the RTL-SDR you’ll first need to edit the “spyserver.config” file which is in the SDR# folder. Open this file with a text editor like Notepad, and set the “device_type” to “RTL-SDR”. Now you can run spyserver.exe on your server and it will use your RTL-SDR. Multiple dongles can be used by editing the “device_serial” string in the config file. Next on the client PC run the latest version of SDR#, and choose the Source as “Spy Server”. Here you can enter your networked PC’s IP address to connect to it.

We tested the updated SpyServer with an RTL-SDR dongle and it worked perfectly. On an 802.11n WiFi connection we were able to stream up to 1 MSPS without problems. 2 MSPS was a bit jittery, but on an Ethernet or 802.11ac WiFi connection it should work with no problems. We also tested connecting two PC’s to a single SpyServer and both were able to run at the same time without trouble. The client which connects first gets to keep control of the center frequency and gain, whilst the second client has those options locked.

SpySever Running with an RTL-SDR Dongle.
SpySever Running with an RTL-SDR Dongle.