Category: HF

A Review of the SDRplay RSP2 by DB Gain

Over on the Utility DXers file section at udxf.nl/ute-info.html, Mr. D.B. Gain has uploaded his latest review of the SDRplay RSP2 (pdf). The SDRplay RSP2 is the successor to the RSP1, and is a 12-bit SDR with tuning range from 10 kHz – 2 GHz. It currently costs $169.95 USD.

DB Gain’s review first covers the features of the RSP2, and some basic SDR vs Analogue theory. He talks a bit about what criteria makes a good SDR and discusses why SDRs are so good for digital work. The review then goes on to talk about the SDRuno software, sensitivity settings, and voice mode work. The review mostly concerns the RSP2’s use on HF, and in this respect DB Gain appears appears to be extremely impressed with the results that the RSP2 gives him.

Previously DB Gain has also reviewed our RTL-SDR V3 dongle (pdf).

The first page of DB Gain's SDRplay RSP2 Review
The first page of DB Gain’s SDRplay RSP2 Review

A Visualization of Yearly Shortwave Activity with WebSDR

The WebSDR from the University of Twente, Netherlands is a wideband HF SDR that is accessible from all over the world via the internet. It was first activated in 2008 making it the very first WebSDR ever. The creator of the service Pieter-Tjerk de Boer PA3FWM has recently made available spectrum image archives which show the HF band conditions over the last two years.

Intrigued by this data, London Shortwave decided to make a timelapse animation of this image data. The results are shown in the videos below, and London Shortwave adds:

The X axis represents the frequency and the Y axis is the time of day, starting at the top. Conventional wisdom about band behaviour can be easily confirmed by watching this video: the 60m, 49m and 41m bands are mostly active after dark, with the 60m and the 49m bands being generally busier during the winter months. The 31m band is most active around sunset, but carries on all night until a few hours after sunrise. The 25m band is active during sunrise and for a few hours afterwards, and around sunset during the winter months, but carries on all night during the summer. Peak activity on the 22m and 19m bands is also clustered bi-modally around the morning and the evening hours, though somewhat closer to the middle of the day than on the 31m and the 25m bands. The 16m band is mostly active during the daylight hours and the 13m band is quiet throughout the year except for the occasional ham contest.

[Fast] Visualising shortwave band activity throughout the year

Visualising shortwave band activity throughout the year

A Tutorial on Receiving WSPR with an RTL-SDR V3

Over on YouTube user Veryokay has uploaded a video that shows how he uses the HF direct sampling mode on one of our V3 RTL-SDR’s to receive WSPR signals. WSPR (pronounced “Whisper”) is short for Weak Signal Propagation Reporting, and is a HF ham mode typically run on very low power levels such as 1W. The data from WSPR reception can be used to determine how good or bad HF propagation is currently around the world as each WSPR message contains the callsign, 6-digit locator and the transmit power level used.

For the antenna Veryokay uses a simple random wire antenna directly connected to the SMA port of the V3 up on top of the roof of his apartment building. This gets him reception good enough to receive many WSPR signals. Then together with SDR#, VB Cable and the WSPR-X decoder software, signals can be received and decoded.

He has also uploaded a document detailing the instructions in text and image form at bit.ly/wspr-rtlsdr.

Easy WSPR reception using $19 RTL-SDR dongle

Setting up Propagation Triggered Spectrum Recording

Over on the SDRplay blog and forums OH2BUA has been sharing how he has set up ‘propagation triggered recording’ by continuously monitoring JT65/JT9 signals with his SDRplay. The idea is that you leave the radio on receiving all night, and set it to automatically start recording IQ files if good propagation conditions occur as determined by the locations received from the JT65/JT9 signal. This may yield some interesting far off stations that can be listened to in the morning, whilst weeding out hours where nothing but commonplace local stations are heard. The software is a simple Windows batch file that works together to coordinate HDSDR and JTDX. It should work with any HF capable SDR.

JT65/JT9 are weak signal propagation HF modes (also known as WSJT modes) that can be decoded all around the world, even with very weak reception thanks to strong digital error correction. They can often be used to determine propagation conditions by determining where successfully decoded messages are being sent from.

OH2BUA writes:

I have made a set of scripts and other files which can be used to build a system which monitors JT65/JT9 (digital modes) amateur radio traffic on 160m/1.8MHz band, and if nice propagation to area you are interested in exists, a MW-BC-band recording is started. When the conditions fall off, the recording is stopped.

There is an attached zip-file containing all the necessary stuff. Sorry this is a windows thing – but easily portable also for linux. Create C:\bat\ and drop all there. Have a look, starting from README.

The default example is to start a MW-band I/Q-recording, if North American ham signals are heard – but it is fully modifiable according to your target when in comes to areas, bands, schedules etc.

The files are available as an attachment to the forum post.

Where WSJT Modes are located (slideplayer.com/slide/4310450)
Where WSJT Modes are located (slideplayer.com/slide/4310450)

Showing the HF Interference Problem from Ethernet over Powerline Devices

Over on our YouTube channel we’ve uploaded a new video that shows how bad the interference from Ethernet over Power devices can be. Ethernet over Power, Powerline Networking, Powerline Communications or ‘HomePlug’ is a technology that allows you to use any of your household power outlets as an internet Ethernet port, completely eliminating the need for runs of Ethernet cabling. They are capable of high speeds and can be used anywhere in the house assuming the two plugs are on the same power circuit.

Unfortunately these devices tend to wipe out almost the entire HF spectrum for anyone listening nearby. As household powerline cables are not shielded for RF emissions they radiate in the HF spectrum quite heavily. In the video we demonstrate what the HF spectrum looks like with one of these devices used in the house. The particular device used was a TP-Link brand adapter, and a WellBrook Magnetic Loop antenna was used outdoors, with the null facing the house. An Airspy R2 with SpyVerter was used to view the spectrum.

The video shows that even when the network is idling there are several brief bursts of noise all over the spectrum. Then when a file is downloaded almost the entire spectrum is completely wiped out.

Interestingly from the video it appears that the amateur radio frequencies are actually carefully notched out and those frequencies remain relatively clean. Most manufacturers of these devices appear to have worked with the ARRL to please ham radio enthusiasts, but SWLers will likely be in trouble if any of these devices are used in your house or neighbors house.

How Ethernet/Internet over Powerline Can Wipe out the HF Band

Lowering the Noise Floor on HF with High Quality Coax

Bonito is a company that sells various products such as their own small active antennas. Some examples are the Bono-Whip (20kHz – 300 MHz), GigaActiv (9kHz – 3 GHz) and the MegaLoop (9kHz – 200 MHz). 

Over on their blog they’ve uploaded a post titled “why even good antennas need good coax cable”. The post explains why high quality heavy shielded coax cable may be required to receive HF signals in noisy environments. The author writes how even placing an antenna in a quiet area outdoors may not work if the coax is still run through an high interference environment, such as through a house.

Typically RG58 cable is most commonly used with HF antennas. However, the author noticed that when using RG58 he was still receiving FM stations, even though the antenna that he was using was a MegaLoop with a built in broadcast FM filter. After switching his RG58 cable to H155 coax, the FM station disappeared. H155 coax is low loss and designed for GHz level frequencies, so it has much better shielding from its tighter braid.

The images below also show the difference in noise floor the author saw after replacing all his RG58 with H155 coax. 

Reception with RG58 Coax
Reception with H155 Coax
Reception with RG58 Coax Reception with H155 Coax
Tweet
Share
Reddit
Vote
Email

A Review of the SDRplay RSP2 by DB Gain

Over on the Utility DXers file section at udxf.nl/ute-info.html, Mr. D.B. Gain has uploaded his latest review of the SDRplay RSP2 (pdf). The SDRplay RSP2 is the successor to the RSP1, and is a 12-bit SDR with tuning range from 10 kHz – 2 GHz. It currently costs $169.95 USD.

DB Gain’s review first covers the features of the RSP2, and some basic SDR vs Analogue theory. He talks a bit about what criteria makes a good SDR and discusses why SDRs are so good for digital work. The review then goes on to talk about the SDRuno software, sensitivity settings, and voice mode work. The review mostly concerns the RSP2’s use on HF, and in this respect DB Gain appears appears to be extremely impressed with the results that the RSP2 gives him.

Previously DB Gain has also reviewed our RTL-SDR V3 dongle (pdf).

The first page of DB Gain's SDRplay RSP2 Review
The first page of DB Gain’s SDRplay RSP2 Review
Tweet
Share
Reddit
Vote
Email

A Visualization of Yearly Shortwave Activity with WebSDR

The WebSDR from the University of Twente, Netherlands is a wideband HF SDR that is accessible from all over the world via the internet. It was first activated in 2008 making it the very first WebSDR ever. The creator of the service Pieter-Tjerk de Boer PA3FWM has recently made available spectrum image archives which show the HF band conditions over the last two years.

Intrigued by this data, London Shortwave decided to make a timelapse animation of this image data. The results are shown in the videos below, and London Shortwave adds:

The X axis represents the frequency and the Y axis is the time of day, starting at the top. Conventional wisdom about band behaviour can be easily confirmed by watching this video: the 60m, 49m and 41m bands are mostly active after dark, with the 60m and the 49m bands being generally busier during the winter months. The 31m band is most active around sunset, but carries on all night until a few hours after sunrise. The 25m band is active during sunrise and for a few hours afterwards, and around sunset during the winter months, but carries on all night during the summer. Peak activity on the 22m and 19m bands is also clustered bi-modally around the morning and the evening hours, though somewhat closer to the middle of the day than on the 31m and the 25m bands. The 16m band is mostly active during the daylight hours and the 13m band is quiet throughout the year except for the occasional ham contest.

[Fast] Visualising shortwave band activity throughout the year

Visualising shortwave band activity throughout the year

Tweet
Share
Reddit
Vote
Email

A Tutorial on Receiving WSPR with an RTL-SDR V3

Over on YouTube user Veryokay has uploaded a video that shows how he uses the HF direct sampling mode on one of our V3 RTL-SDR’s to receive WSPR signals. WSPR (pronounced “Whisper”) is short for Weak Signal Propagation Reporting, and is a HF ham mode typically run on very low power levels such as 1W. The data from WSPR reception can be used to determine how good or bad HF propagation is currently around the world as each WSPR message contains the callsign, 6-digit locator and the transmit power level used.

For the antenna Veryokay uses a simple random wire antenna directly connected to the SMA port of the V3 up on top of the roof of his apartment building. This gets him reception good enough to receive many WSPR signals. Then together with SDR#, VB Cable and the WSPR-X decoder software, signals can be received and decoded.

He has also uploaded a document detailing the instructions in text and image form at bit.ly/wspr-rtlsdr.

Easy WSPR reception using $19 RTL-SDR dongle

Tweet21
Share
Reddit
Vote
Email
21 Shares

Setting up Propagation Triggered Spectrum Recording

Over on the SDRplay blog and forums OH2BUA has been sharing how he has set up ‘propagation triggered recording’ by continuously monitoring JT65/JT9 signals with his SDRplay. The idea is that you leave the radio on receiving all night, and set it to automatically start recording IQ files if good propagation conditions occur as determined by the locations received from the JT65/JT9 signal. This may yield some interesting far off stations that can be listened to in the morning, whilst weeding out hours where nothing but commonplace local stations are heard. The software is a simple Windows batch file that works together to coordinate HDSDR and JTDX. It should work with any HF capable SDR.

JT65/JT9 are weak signal propagation HF modes (also known as WSJT modes) that can be decoded all around the world, even with very weak reception thanks to strong digital error correction. They can often be used to determine propagation conditions by determining where successfully decoded messages are being sent from.

OH2BUA writes:

I have made a set of scripts and other files which can be used to build a system which monitors JT65/JT9 (digital modes) amateur radio traffic on 160m/1.8MHz band, and if nice propagation to area you are interested in exists, a MW-BC-band recording is started. When the conditions fall off, the recording is stopped.

There is an attached zip-file containing all the necessary stuff. Sorry this is a windows thing – but easily portable also for linux. Create C:\bat\ and drop all there. Have a look, starting from README.

The default example is to start a MW-band I/Q-recording, if North American ham signals are heard – but it is fully modifiable according to your target when in comes to areas, bands, schedules etc.

The files are available as an attachment to the forum post.

Where WSJT Modes are located (slideplayer.com/slide/4310450)
Where WSJT Modes are located (slideplayer.com/slide/4310450)
Tweet10
Share
Reddit
Vote
Email
10 Shares

Showing the HF Interference Problem from Ethernet over Powerline Devices

Over on our YouTube channel we’ve uploaded a new video that shows how bad the interference from Ethernet over Power devices can be. Ethernet over Power, Powerline Networking, Powerline Communications or ‘HomePlug’ is a technology that allows you to use any of your household power outlets as an internet Ethernet port, completely eliminating the need for runs of Ethernet cabling. They are capable of high speeds and can be used anywhere in the house assuming the two plugs are on the same power circuit.

Unfortunately these devices tend to wipe out almost the entire HF spectrum for anyone listening nearby. As household powerline cables are not shielded for RF emissions they radiate in the HF spectrum quite heavily. In the video we demonstrate what the HF spectrum looks like with one of these devices used in the house. The particular device used was a TP-Link brand adapter, and a WellBrook Magnetic Loop antenna was used outdoors, with the null facing the house. An Airspy R2 with SpyVerter was used to view the spectrum.

The video shows that even when the network is idling there are several brief bursts of noise all over the spectrum. Then when a file is downloaded almost the entire spectrum is completely wiped out.

Interestingly from the video it appears that the amateur radio frequencies are actually carefully notched out and those frequencies remain relatively clean. Most manufacturers of these devices appear to have worked with the ARRL to please ham radio enthusiasts, but SWLers will likely be in trouble if any of these devices are used in your house or neighbors house.

How Ethernet/Internet over Powerline Can Wipe out the HF Band

Tweet26
Share
Reddit
Vote
Email
26 Shares

Lowering the Noise Floor on HF with High Quality Coax

Bonito is a company that sells various products such as their own small active antennas. Some examples are the Bono-Whip (20kHz – 300 MHz), GigaActiv (9kHz – 3 GHz) and the MegaLoop (9kHz – 200 MHz). 

Over on their blog they’ve uploaded a post titled “why even good antennas need good coax cable”. The post explains why high quality heavy shielded coax cable may be required to receive HF signals in noisy environments. The author writes how even placing an antenna in a quiet area outdoors may not work if the coax is still run through an high interference environment, such as through a house.

Typically RG58 cable is most commonly used with HF antennas. However, the author noticed that when using RG58 he was still receiving FM stations, even though the antenna that he was using was a MegaLoop with a built in broadcast FM filter. After switching his RG58 cable to H155 coax, the FM station disappeared. H155 coax is low loss and designed for GHz level frequencies, so it has much better shielding from its tighter braid.

The images below also show the difference in noise floor the author saw after replacing all his RG58 with H155 coax. 

Reception with RG58 Coax
Reception with H155 Coax
Reception with RG58 Coax Reception with H155 Coax
Tweet12
Share
Reddit
Vote
Email
12 Shares

Analyzing HF Over the Horizon Radar in GNU Radio

Over the Horizon radar is typically used at HF frequencies and is used to detect targets from hundreds to thousands of kilometers away from the radar station. On HF they are very common and can be easily heard as continuous or bursty buzzing sounds.

Over on his blog Daniel Estevez writes how he was inspired by Balint Seebers GRCon16 talk to perform his own investigations into HF OTH radar. Daniel first analyzed a recorded IQ signal of a presumed Russian radar in Audacity, and noticed that it consisted of 15 kHz wide pulses repeated at 50 Hz intervals. He then used GNU Radio and the Quadrature Demod block to FM demodulate the pulse and see how the frequency changes over time. From this he was able to determine the original transmitted radar pulse characteristics

Next he performs pulse compression, which is essentially a cross correlation of the received pulse and transmitted pulse which was determined from the characteristics found earlier. The signal being received at Daniels location is distorted, because it will arrive from multiple paths, since the signal will bounce of multiple layers of the ionosphere. With this pulse compression technique Daniel is able to determine the time of flight for the different multi-path components of the received pulse. By graphing all the results over time he was able to obtain this image illustrating relative propagation distance over time.

Check out Daniels post for the full details and his code.

Ionosphere Propagation Graph
Ionosphere Propagation Graph
Tweet11
Share
Reddit
Vote
Email
11 Shares

Receiving CB Radio with an RTL-SDR Dongle

Back in July we posted a story by Mario Fillipi (N2HUN) who wrote an article about using the RTL-SDR to receive CB radio, and how while the CB radio heyday is over, there are still opportunities for good listening available today.

Recently Mario has posted a new article on swling.com where he discusses his CB radio listening hobby further. To listen to the CB band at 26.965 – 27.405 MHz he uses an RTL-SDR dongle together with a ham-it-up upconverter. While an upconverter is not required since most RTL-SDR dongles typically tune down to 24-25 MHz, he finds that using one helps because it can help block out interference from the strong broadcast FM band.  We note that you could also use one of our BCFM Block filters for the same purpose.

Mario notes that recently he noticed the CB band was open during the night. Usually the frequencies that CB radio uses propagate best during the daytime, and poorly at night. But on some occasions it can open up at night as well. He writes that on some occasions during a winters night during a snowstorm he has been able to receive the world on CB, from Europe, the Caribbean and Australia.

CB Band Voice in SDR# with an RTL-SDR and Ham-it-up Upconverter
CB Band Voice in SDR# with an RTL-SDR and Ham-it-up Upconverter
Tweet
Share
Reddit
Vote
Email