Category: HF

HF Reception with an EeePC and an RTL-SDR Blog V3 Running on a Raspberry Pi with SpyServer

Over on YouTube user IW2DZX has uploaded a video showing him using an old EeePC 900 to receive HF with an RTL-SDR V3 running in direct sampling mode on a Raspberry Pi 3 which is running a SpyServer. An EeePC 900 is an old netbook that was released in 2008 which is lightweight, portable and was fairly cheap. Second hand Eeepc's can now be found on eBay for less than $60 US.

By running the RTL-SDR on a Raspberry Pi 3 with SpyServer the need to have the dongle connected to the netbook is eliminated. Instead the radio data from the RTL-SDR is efficiently sent over a network connection and received via the WiFi on the Eeepc. 

Adam Tests his UP-64 Upconverter with an RTL-SDR

Over on YouTube Adam 9A4QV has uploaded a video of him testing out his 'UP-64' upconverter together with an RTL-SDR. An upconverter moves low frequencies 'up' into a higher frequency. This is useful for HF reception, as normal reception on an RTL-SDR starts at about 24 MHz (without using direct sampling mode).

Adam previously manufactured and sold his UP-100 upconverter, which was an upconverter of his own design that utilized a 100 MHz oscillator. These days it has been accepted that using an upconversion frequency that avoids the broadcast FM band is generally better as it avoids the interference that can come from very strong FM signals. The 64 MHz oscillator on the UP-64 avoids the broadcast FM band for the most part unlike the older UP-100.

Simon Brown Compares the Airspy HF+ against the RFSpace NetSDR on SDR-Console V3

Simon Brown who is the author of the popular SDR-Console V2/V3 software has received an early review version of the Airspy HF+ and has uploaded some screenshots comparing it with the RFSpace NetSDR. The NetSDR is a high performance 16-bit DDC SDR with frequency range of 10 KHz – 32 MHz, and a bandwidth of up to 1.6 MHz. The base price of the NetSDR is US $1449.

The Airspy HF+ on the other hand is based on a polyphase harmonic rejection mixer design with 18-bit DDC and has a frequency range of DC – 31 MHz and 60 – 260 MHz, with a maximum bandwidth of up to 660 kHZ. It is not yet released, but is expected to be about US $149 shipped from China.

Simon’s screenshots show that despite its low cost the HF+ seems to perform just as well as the more expensive NetSDR.

If you’re interested in the HF+ we also have our own review available here.

New HF+ photo, with black metal enclosure.
New HF+ photo, with black metal enclosure.

Tom’s Radio Room Show Tests the RTL-SDR Blog Broadcast AM Filter

Over on YouTube Tom from Tom’s Radio Radio Room Show (TRRS) has uploaded a video showing the effectiveness of our broadcast AM (BCAM) filters for cleaning up HF reception. In the video he uses an RSP1 to receive the WWV time signal at 5 MHz and shows that there is some AM signals mixing into the audio. After connecting the BCAM filter the AM signal is gone and WWV comes in clearer.

Gospell GR-227: New SDR Based Digital Broadcast Radio Adapter for Cars

Over on the SWLing Post blog we’ve seen news of this new SDR based car radio called the Gospell GR-227. Gospell is a Chinese manufacturer of various broadcast consumer radio products including DRM receivers. It is intended to be an adapter for your car that lets you listen to digital broadcast stations such as DAB/DAB+ on VHF and DRM on UHF, but it can also be used for standard AM and FM reception. From the product sheet it looks like it will simply plug into you car USB port, and output audio through that port into your cars head unit. Control of the unit is through an Android app.

There doesn’t seem to be anything stopping someone from using this outside of a car though, so perhaps depending on the price and software hackability available it might make a good PC or Raspberry Pi based HF receiver for all modulation types too.

Over on the Gospell Facebook page are images showing the Gospell running at IBC 2017 and next to other upcoming SDR based digital broadcast receivers like the Titus II.

Gospell SDR Connected to a Car Radio Head Unit
Gospell SDR Connected to a Car Radio Head Unit

No word yet on a release date or pricing. The press release reads:

Chengdu, China, September 04, 2017 – A new adaptor specifically designed for in-car use that simplifies digital radio on the road will be introduced at IBC by Gospell.

GR-227 is a small, low-cost adaptor that acts as an aftermarket add-on to car stereos receiving high-quality digital broadcast programs and data application, and serving it to the car audio system over a USB cable. Based on software defined radio technology, GR-227 is compatible with DAB, DAB+, DRM and is DRM+ ready. It is also powerful enough to support digital audio decoding such as extended HE-AAC (xHE-AAC).

GR-227 literally works with any kind of car stereos with a USB port. Our patent pending technology allows the adaptor to behave like a thumb drive when plug into a USB port and makes it compatible with most of the music players not only in car but also for home use.

To make the most of GR-227, the Gospell Smart Tune App for Android has been included to add more features. When partnered with an Android powered car stereo, the App not only allows for playback of the broadcast audio program but data application which brings much fun to car entertainment.

By connecting the supplied triple band active antenna which can be attached to the windscreen through the SMA antenna connector, the reception in DRM, FM and DAB bands can be significantly improved, offering maximum flexibility between different broadcasting standards.

Installing the plug-and-play GR-227 adaptor to your car is easy and doesn’t require changing your car stereo. It is one of the easiest ways to upgrade your car radio to digital without replacing anything.

The Gospell’s aftermarket car adaptor range starts with USB model but more will follow to support more car stereo types.

Haochun Liu, DRM director, Gospell, said: “By leveraging SDR, we can now combine multiple broadcasting standards together to offer flexibility and cost advantages, coupled with easy installation without the necessity of buying a new car stereo as in traditional solutions.”

For additional information, please visit www.goscas.com or contact Gospell sales at [email protected]

About Gospell

Founded in 1993, Gospell Digital Technology Co Ltd (GOSPELL). is a private hi-tech enterprise with R&D, manufacturing, business consultancy and planning, trade, delivery, project implementation and after sales service, acting as a complete DTV and triple-play solution provider for Digital TV/OTT related projects. Headquartered in GOSPELL INDUSTRIAL PARK at Chenzhou, Hunan Province for CPE related production manufacturing, GOSPELL also has its office in Shenzhen for business/marketing management and administration, in Chengdu for R&D and headend/transmitter system production/debugging and Customer Service Center, and in 12 cities in China as well as international offices in India, Africa and Mexico.

[First seen on swling.com/blog]

A Homebrew One Transistor Upconverter for the RTL-SDR

Recently Qrp Gaijin wrote in to us and wanted to share his experiences on building a one transistor diode-ring mixer upconverter for his RTL-SDR. An upconverter for the RTL-SDR translates low HF frequencies ‘up’ into ones that are receivable by the RTL-SDR. This is a different method to the direct sampling mode used in the V3 dongles to achieve HF reception.

Qrp Gaijin’s post goes into some detail about his circuit and shows the schematic as well. He also shows the results with an active loop antenna, RTL-SDR and the upconverter in some videos. In the email to us he also notes that his upconverter is still a work in progress as the LO is quite noisy and he suspects that it may be too weak to drive the 1N4148 based diode ring mixer. There is also no filtering on the circuit yet, so there is some broadcast FM breakthrough.

Another project he worked on was attempting the direct sampling mod on a standard RTL-SDR. However, Qrp Gaijin’s method is slightly different to most attempts as instead of soldering the wires into the Q-branch holes he simply uses hot glue to hold them mechanically in place. This may be an idea to consider for those who want to attempt the mod on a standard RTL-SDR, but don’t have any soldering tools or experience.

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.

svr2_1
svr2_2

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.

HF Reception with an EeePC and an RTL-SDR Blog V3 Running on a Raspberry Pi with SpyServer

Over on YouTube user IW2DZX has uploaded a video showing him using an old EeePC 900 to receive HF with an RTL-SDR V3 running in direct sampling mode on a Raspberry Pi 3 which is running a SpyServer. An EeePC 900 is an old netbook that was released in 2008 which is lightweight, portable and was fairly cheap. Second hand Eeepc's can now be found on eBay for less than $60 US.

By running the RTL-SDR on a Raspberry Pi 3 with SpyServer the need to have the dongle connected to the netbook is eliminated. Instead the radio data from the RTL-SDR is efficiently sent over a network connection and received via the WiFi on the Eeepc. 

Adam Tests his UP-64 Upconverter with an RTL-SDR

Over on YouTube Adam 9A4QV has uploaded a video of him testing out his 'UP-64' upconverter together with an RTL-SDR. An upconverter moves low frequencies 'up' into a higher frequency. This is useful for HF reception, as normal reception on an RTL-SDR starts at about 24 MHz (without using direct sampling mode).

Adam previously manufactured and sold his UP-100 upconverter, which was an upconverter of his own design that utilized a 100 MHz oscillator. These days it has been accepted that using an upconversion frequency that avoids the broadcast FM band is generally better as it avoids the interference that can come from very strong FM signals. The 64 MHz oscillator on the UP-64 avoids the broadcast FM band for the most part unlike the older UP-100.

Simon Brown Compares the Airspy HF+ against the RFSpace NetSDR on SDR-Console V3

Simon Brown who is the author of the popular SDR-Console V2/V3 software has received an early review version of the Airspy HF+ and has uploaded some screenshots comparing it with the RFSpace NetSDR. The NetSDR is a high performance 16-bit DDC SDR with frequency range of 10 KHz – 32 MHz, and a bandwidth of up to 1.6 MHz. The base price of the NetSDR is US $1449.

The Airspy HF+ on the other hand is based on a polyphase harmonic rejection mixer design with 18-bit DDC and has a frequency range of DC – 31 MHz and 60 – 260 MHz, with a maximum bandwidth of up to 660 kHZ. It is not yet released, but is expected to be about US $149 shipped from China.

Simon’s screenshots show that despite its low cost the HF+ seems to perform just as well as the more expensive NetSDR.

If you’re interested in the HF+ we also have our own review available here.

New HF+ photo, with black metal enclosure.
New HF+ photo, with black metal enclosure.

Tom’s Radio Room Show Tests the RTL-SDR Blog Broadcast AM Filter

Over on YouTube Tom from Tom’s Radio Radio Room Show (TRRS) has uploaded a video showing the effectiveness of our broadcast AM (BCAM) filters for cleaning up HF reception. In the video he uses an RSP1 to receive the WWV time signal at 5 MHz and shows that there is some AM signals mixing into the audio. After connecting the BCAM filter the AM signal is gone and WWV comes in clearer.

Gospell GR-227: New SDR Based Digital Broadcast Radio Adapter for Cars

Over on the SWLing Post blog we’ve seen news of this new SDR based car radio called the Gospell GR-227. Gospell is a Chinese manufacturer of various broadcast consumer radio products including DRM receivers. It is intended to be an adapter for your car that lets you listen to digital broadcast stations such as DAB/DAB+ on VHF and DRM on UHF, but it can also be used for standard AM and FM reception. From the product sheet it looks like it will simply plug into you car USB port, and output audio through that port into your cars head unit. Control of the unit is through an Android app.

There doesn’t seem to be anything stopping someone from using this outside of a car though, so perhaps depending on the price and software hackability available it might make a good PC or Raspberry Pi based HF receiver for all modulation types too.

Over on the Gospell Facebook page are images showing the Gospell running at IBC 2017 and next to other upcoming SDR based digital broadcast receivers like the Titus II.

Gospell SDR Connected to a Car Radio Head Unit
Gospell SDR Connected to a Car Radio Head Unit

No word yet on a release date or pricing. The press release reads:

Chengdu, China, September 04, 2017 – A new adaptor specifically designed for in-car use that simplifies digital radio on the road will be introduced at IBC by Gospell.

GR-227 is a small, low-cost adaptor that acts as an aftermarket add-on to car stereos receiving high-quality digital broadcast programs and data application, and serving it to the car audio system over a USB cable. Based on software defined radio technology, GR-227 is compatible with DAB, DAB+, DRM and is DRM+ ready. It is also powerful enough to support digital audio decoding such as extended HE-AAC (xHE-AAC).

GR-227 literally works with any kind of car stereos with a USB port. Our patent pending technology allows the adaptor to behave like a thumb drive when plug into a USB port and makes it compatible with most of the music players not only in car but also for home use.

To make the most of GR-227, the Gospell Smart Tune App for Android has been included to add more features. When partnered with an Android powered car stereo, the App not only allows for playback of the broadcast audio program but data application which brings much fun to car entertainment.

By connecting the supplied triple band active antenna which can be attached to the windscreen through the SMA antenna connector, the reception in DRM, FM and DAB bands can be significantly improved, offering maximum flexibility between different broadcasting standards.

Installing the plug-and-play GR-227 adaptor to your car is easy and doesn’t require changing your car stereo. It is one of the easiest ways to upgrade your car radio to digital without replacing anything.

The Gospell’s aftermarket car adaptor range starts with USB model but more will follow to support more car stereo types.

Haochun Liu, DRM director, Gospell, said: “By leveraging SDR, we can now combine multiple broadcasting standards together to offer flexibility and cost advantages, coupled with easy installation without the necessity of buying a new car stereo as in traditional solutions.”

For additional information, please visit www.goscas.com or contact Gospell sales at [email protected]

About Gospell

Founded in 1993, Gospell Digital Technology Co Ltd (GOSPELL). is a private hi-tech enterprise with R&D, manufacturing, business consultancy and planning, trade, delivery, project implementation and after sales service, acting as a complete DTV and triple-play solution provider for Digital TV/OTT related projects. Headquartered in GOSPELL INDUSTRIAL PARK at Chenzhou, Hunan Province for CPE related production manufacturing, GOSPELL also has its office in Shenzhen for business/marketing management and administration, in Chengdu for R&D and headend/transmitter system production/debugging and Customer Service Center, and in 12 cities in China as well as international offices in India, Africa and Mexico.

[First seen on swling.com/blog]

A Homebrew One Transistor Upconverter for the RTL-SDR

Recently Qrp Gaijin wrote in to us and wanted to share his experiences on building a one transistor diode-ring mixer upconverter for his RTL-SDR. An upconverter for the RTL-SDR translates low HF frequencies ‘up’ into ones that are receivable by the RTL-SDR. This is a different method to the direct sampling mode used in the V3 dongles to achieve HF reception.

Qrp Gaijin’s post goes into some detail about his circuit and shows the schematic as well. He also shows the results with an active loop antenna, RTL-SDR and the upconverter in some videos. In the email to us he also notes that his upconverter is still a work in progress as the LO is quite noisy and he suspects that it may be too weak to drive the 1N4148 based diode ring mixer. There is also no filtering on the circuit yet, so there is some broadcast FM breakthrough.

Another project he worked on was attempting the direct sampling mod on a standard RTL-SDR. However, Qrp Gaijin’s method is slightly different to most attempts as instead of soldering the wires into the Q-branch holes he simply uses hot glue to hold them mechanically in place. This may be an idea to consider for those who want to attempt the mod on a standard RTL-SDR, but don’t have any soldering tools or experience.

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.

svr2_1
svr2_2

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.

Using the SDRplay with a W4OP Loop

Over on YouTube user SignalSearch has uploaded a video showing and explaining the use of a W4OP magnetic loop antenna on a SDRplay SDR. On the video he explains what the W4OP loop is, and demonstrates it’s operation in SDR-Console with his SDRplay. The video description reads:

Experiment: Hookup the SDRPlay RSP 1 (SDR receiver) to the W4OP (Small Transmitting Loop). I’ve always wanted to try hooking up a loop to my SDRPlay. Though different from an active receive loop (one that has a Low Noise Amplifier), this loop can be used for transmitting @ QRP levels – but works great for shortwave listening too! For more info. please visit my website @ www.k5acl.net!