YouTube user tvdxrools . has posted a short video showing what solar activity noise from the sun looks like on the waterfall at 31 MHz. He used an RTL-SDR dongle and 1/2 wave vertical antenna.
Image may be NSFW.
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There is an amateur radio group in Germany known as DL0SHF which transmits a 10 GHz (QRG = 10.368.025 MHz) beacon at the moon whenever it is visible at their site. The goal of this transmission is to detect the very weak beacon reflection.
Amateur radio hobbyist Rein (W6SZ) has written in to let us know about his, DK7IJ’s and the DL0SHF groups success with receiving the beacon using the RTL-SDR. He writes
DL0SHF transmit a signal to the moon when the moon is visible at the site. The run 2 modes 50 and 500 W output, 20 seconds on, 40 seconds off.
Last night, I managed to detect the beacon with a very simple receiving package. Amazing enough, using WSJT moon tracking data, the signal appeared right away when the moon appeared here above the trees.
The signal lasts only 20 seconds but then 40 seconds later, it returned! By the books.
I use a simple 10 GHz receiver here that I use for scouting signals on 10 GHz terrestrial as member of the San Bernardino Microwave Society.
It consists of a RTL Dongle IF block tuned to 618 MHz as IF.
Front-end is a PLL LNB, not modified, running with 9.750 GHz LOThe LNB is powered with 12 Volts by means of a Bias Tee.
Both items can be acquired for about USD 25.- on eBay and other places.
The antenna is a standard 18 inch satellite off-set dish.
The antenna has some elevation control and the feed ( LNB ) can be rotated for polarity control.
Every variable is manually operated.
At times I measured the beacon as high as 15 dB above the noise using HDSDR as DSP processor software.
The beacon was running in the 500 W output mode during these observations.
The post Receiving a 10 GHz Reflected Moon Beacon with the RTL-SDR appeared first on rtl-sdr.com.
YouTube user Tim Havens has uploaded two videos showing his meteor detection results with an RTL-SDR dongle. Tim uses a stock R820T dongle, and a 6 element yagi antenna with LNA.
For the software he uses Spectrum Lab and SDRSharp.
Update: Tehrasha from the comments section has found a page by Tim Havens showing a little information on his meteor detection setup.
Image may be NSFW.
Clik here to view.
Image may be NSFW.
Clik here to view.
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Over on our Facebook page member Александр has let us know about a Russian amateur astronomer, Alex who has been using the RTL-SDR for radio astronomy. Alex uses an Elonics E4000 RTL-SDR combined with a 3.7m mesh parabola dish with 1420 MHz waveguide.
At the center of his system is an LNA with 40dB gain and a very low noise figure of 0.2dB. This LNA appears to be based on G4DDK’s VLNA, but modified to work with the 1420 MHz frequency used for radio astronomy. It seems the LNA can be ordered for 140 USD from the above link.
Note: The above Russian links are machine translated with Google to English.
The post Radio Astronomy with a 0.2dB Noise Figure LNA appeared first on rtl-sdr.com.
On his website, David has posted a page showing his results with an “Itty Bitty Radio Telescope” connected to an RTL-SDR dongle. The Itty Bitty Radio Telescope is a small radio telescope that can be used for simple and educational radio astronomy experiments. The telescope consists of an 18 inch directv satellite dish with low noise block (LNB), a satellite finder and an RTL-SDR dongle connected to a laptop.
The LNB converts input frequencies of 12.2 GHz to 12.7 GHz down to 950 MHz to 1.45 GHz which is a range that the RTL-SDR can receive. In his YouTube video posted below David points his Itty Bitty Radio Telescope at the sun and shows the associated increase in the noise floor on SDR# due to solar radio emissions. More information and possible experiments with the Itty Bitty Radio Telescope can be found in this PDF.
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Amateur radio astronomer Y1PWE has uploaded a pdf document describing how he created a low cost hydrogen line telescope using an RTL-SDR dongle. Hydrogen atoms randomly emit photons at a wavelength of 21cm (1420.4058 MHz). Normally a single hydrogen atom will rarely emit a photon, but since space and the galaxy is filled with many hydrogen atoms the average effect is an observable RF power spike at 1420.4058 MHz. By pointing a radio telescope at the night sky, a power spike indicating the hydrogen line can be observed in a frequency spectrum plot.
Y1PWE created a radio telescope using a quad 22 element yagi antenna, several LNA’s and filters and an RTL-SDR dongle and laptop. Using this setup he can capture some raw IQ data from the RTL-SDR and then use an FFT averaging program to produce some plots. In his plots the hydrogen line is clearly visible.
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The ISEE-3 is a exploratory spacecraft that was launched in 1978 and placed in an orbit around the sun. It was mission was to study the interaction between solar wind and the earth’s magnetic field and was later the first spacecraft to pass through the tail of a comet. NASA suspended communications with the spacecraft in 1997 and it was last heard of in 2008.
Recently there has been interest in rebooting the spacecraft and bringing it back into an earth orbit. Once safely in orbit the spacecraft’s science instruments would be made publicly available for educational purposes. Unfortunately, the RF communications hardware and knowledge that was used to interface with the spacecraft has long been lost.
Luckily, the scientists and engineers at Ettus were able to devise a plan that would use the world’s largest single dish radio telescope at Arecibo connected to some of their USRP N210 SDR radios to contact the probe. The USRP N210 is an advanced software defined radio that sells for around $1700 USD. Using their setup together with GNU Radio and the spacecraft’s documentation from NASA they were able to make contact with the spacecraft and fire the thrusters. They have yet to actually correct the trajectory which will bring it back to earth, but they hope to be able to do that soon.
The post Rebooting the ISEE-3 with USRP Software Defined Radios appeared first on rtl-sdr.com.
Amateur radio astronomy hobbyist Jim Sky has written on his blog about his new program called RTL Bridge with allows the RTL-SDR to directly connect to his other radio astronomy programs Radio-SkyPipe and Radio-Sky Spectrograph. Jim describes his two existing program as follows.
Radio-Sky Spectrograph displays a waterfall spectrum. It is not so different from other programs that produce these displays except that it saves the spectra at a manageable data rate and provides channel widths that are consistent with many natural radio signal bandwidths. For terrestrial , solar flare, Jupiter decametric, or emission/absorption observations you might want to use RSS.
Radio-SkyPipe is a souped-up strip chart program which plots signal strength over time. When getting its data from RTL Bridge, RSP is plotting the total power in the spectrum covered by the RTL receiver centered around its set frequency. While the raw values are proportional to power, you will have to apply a function via the RSP Equations feature to apply a calibration if you want absolute values. For signals that do not have significant spectral structure of interest, this would be the preferred way to plot the data.
The post Radio Astronomy with RTL Bridge and Radio-Sky Spectrograph appeared first on rtl-sdr.com.
SDR Touch, the popular Android based software defined radio software for the RTL-SDR has been updated to version 2.0. This new version is a complete rewrite with many optimizations listed below.
The author also writes that the rewrite allows for new features coming out in the future such as adjustable bandwidth, FFT size, plugins and a separate GUI for in-car use. SDR Touch is available from the Android Play store.
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Over on YouTube user S53RM has uploaded a video showing his and S53MM’s observation of the 1420 MHz galactic hydrogen line with an RTL-SDR. Hydrogen atoms randomly emit photons at a wavelength of 21cm (1420.4058 MHz). Normally a single hydrogen atom will rarely emit a photon, but since space and the galaxy is filled with many hydrogen atoms the average effect is an observable RF power spike at 1420.4058 MHz. By pointing a radio telescope at the night sky, a power spike indicating the hydrogen line can be observed in a frequency spectrum plot.
In the video they rotate their 3.6m parabolic mesh antenna dish along the Milky Way. As the dish rotates doppler shifted hydrogen line peaks can be observed on Linrad, each peak representing a different arm of the galaxy. The galaxy consists of several spinning arms, some spinning faster than others which causes the hydrogen line peaks produced by the arms to be doppler shifted by different amounts.
They used Linrad to plot the RF spectrum as they were able to use it together with a pulse generator to calibrate the RTL-SDR for a flatter frequency response.
More information about their project can be found at http://lea.hamradio.si/~s53rm/Radio%20Astronomy.htm.
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The post Observing the 21cm Hydrogen Line with Linrad and an RTL-SDR appeared first on rtl-sdr.com.
Amateur radio astronomer Marcus Leech often makes use of RTL-SDR dongles for his amateur radio astronomy experiments. Recently Marcus wrote a technical paper discussing a modern SDR implementation of a Dicke Radiometer, which is a type of radio telescope that is designed to significantly reduce the effects of receiver noise. Marcus has also developed an RTL-SDR approach to another similar system called the Phase-Switched Interferometer.
Using his new SDR based approach together with GNU Radio, a 10ft satellite dish and two RTL-SDR dongles he was able to plot a transit of the Milky Way Galaxy as shown below.
The post Radio Astronomy using a Differential Radiometer and Interferometer with an RTL-SDR appeared first on rtl-sdr.com.
Back in 2013 we posted about a Dr. David Morgan who had written a tutorial paper discussing how he used the Funcube Dongle Pro+ for radio astronomy. Recently Dr Morgan has also written another paper showing how to use the RTL-SDR together with the Spectrum Lab software to detect meteors. A software defined radio can be used to detect and count meteors entering the earth’s atmosphere by detecting strong radio waves reflected by ionized trails left by the meteor.
If you are unfamiliar with how to detect meteors using radio waves, you should consult Dr Morgans older papers called Detection of Meteors by RADAR, Meteor Radar SDR Receiver (Funcube Dongle), and Antennas for Meteor Scatter.
The tutorial shows how to set up SDR# and Spectrum Lab to work together to detect meteors using the Graves Radar in France at 143.050 MHz.
The post Techniques for using the RTL Dongle for Detecting Meteors appeared first on rtl-sdr.com.
Recently amateur radio astronomer Jim Brown used an RTL-SDR dongle together with a Ham-it-up upconverter and preamp to capture noise bursts from the planet Jupiter. Not much information about his observations are available yet as he has not yet made a write up, but he has given the image of the noise burst shown below to Jim Sky, programmer of RTL Bridge and Radio-Sky Spectograph which is some of the software used to capture the noise bursts. We will make another post in the future if Jim Brown does a write up.
Jim Sky has also updated his RTL Bridge software to use Oliver Jowetts patched drivers, which allow the RTL-SDR to receive below its usual 24 MHz limit.
The post Capturing Noise Bursts from Jupiter with an RTL-SDR appeared first on rtl-sdr.com.
Amateur Radio astronomer Peter Kalberla recently wrote in to let us know about a paper he has written exploring stability issues and comparing the R820T and R820T2 RTL-SDR tuner chips (pdf warning). The R820T2 tuner is an upgrade to the R820T tuner which is used in the most commonly found RTL-SDR dongles.
Peters first results show that the R820T2 has better reception and less spurious features at frequencies above about 1.45 GHz and improved frequency stability (with the newer R820T2 dongles that use the SMD oscillator). His second set of results explore issues that are more closely relevant to radio astronomy including observed spectra, Allan variance (frequency stability) tests and determining the shape of the R820T/2 internal bandpass filter.
In the conclusion of the paper Peter writes:
Two Newsky RTL2838U dongles were tested, the R820T2 device against the R820T. The evaluation results in a clear preference for the new RTL2838U/R820T2 dongle. In the L-band the new dongle is at least 2.7 dB more sensitive. According to the radiometer equation the effective system temperature is reduced by almost 50%. Most important for reliable radio astronomical observations are stability issues. Allan variance tests have shown that the R820T2 dongle is far better then the older version. The stability is comparable to that of professional radio astronomical devices. The tests have shown that using the full bandwidth of the RTL-SDR devices results in spurious baseline ripples. For a good performance it is recommended to use the dongles at reduced bandwidth. rtl power with the crop option -c 0.5 appears to be a good choice.
The post RTL-SDR Tests: R820T vs R820T2 Stability Tests for Radio Astronomy appeared first on rtl-sdr.com.
With an RTL-SDR or other radio it is possible to record the echoes of the 143.050 MHz Graves radar bouncing off the ionized trails of meteors. This is called meteor scatter and it is usually used to count the number of meteors entering the atmosphere. Amateur radio astronomers EA4EOZ and EB3FRN decided to take this idea further and synchronised their separate receivers and recordings with a PPS GPS signal in order to determine the radiant of the meteors they detected. They write:
The idea was to analyze the Doppler from the head echoes and and see if something useful can be extracted from them.
We detected a meteor from two distant locations and measured Doppler and Doppler slope at those locations. The we tried to find solutions to the meteor equation by brute force until we obtain a big number of them. Then we plotted those solutions in the sky and we see some of them pass near a known active radiant at the time of observation. Then, we checked the velocity of those solutions near the known radiant and found they are quite similar to the velocity of the known radiant, so we concluded probably they come from that radiant.
But they can come from everywhere else in the sky along the solution lines! There is not guarantee these meteors to be Geminids, although probabilities are high. Once all the possible radiants of a meteor are plotted into the sky, there is no way to know who of all them was the real one. Doppler only measurement from two different places is not enough to determine a meteor radiant. But don’t forget with some meteors, suspect to come from a known shower, the possible results includes the right radiant at the known meteor velocity for that radiant, so there seems to be some solid base fundamentals in this experiment.
Initially they ran into a little trouble with their sound cards, as it turns out that sound cards don’t exactly sample at their exact specified sample rate. After properly resampling their sound files they were able to create a stereo wav file (one receiver on the left channel, one receiver on the right channel) which showed that the doppler signature was different in each location. The video below shows this wav file.
Using the information from their two separate recordings, they were able to do some doppler math, and determine a set of possible locations for the radiant of the meteors (it was not possible to pinpoint the exact location due to there being no inverse to the doppler equation). The radiant of a meteor shower is the point in the sky at which the meteors appear to be originating from. Although their solution couldn’t exactly pinpoint the location, some of the possible solutions from most meteors passed through the known radiant of the Geminids meteor shower. With more measurement locations the exact location could be pinpointed more accurately.
The post Determining the Radiant of Meteors using the Graves Radar appeared first on rtl-sdr.com.
Radio-Sky Spectrograph is a software application that is designed to produce waterfall displays similar to other software, but with a focus on observing radio astronomy phenomena.
Radio-Sky Spectrograph displays a waterfall spectrum. It is not so different from other programs that produce these displays except that it saves the spectra at a manageable data rate and provides channel widths that are consistent with many natural radio signal bandwidths. For terrestrial, solar flare, Jupiter decametric, or emission/absorption observations you might want to use RSS [Radio-Sky Spectrograph].
Last year, we posted about the release of RTL_Bridge, which is a program designed to interface an RTL-SDR dongle with Radio-Sky Spectrograph. One limitation with RTL_Bridge was that it was limited to the dongles maximum bandwidth of about 2.4 MHz. Now Raydel Abreu Espinet (CM2ESP) has written a new application called RTL-WideSpectrum which allows for wideband spectral sweeps in Radio-Sky Spectrograph by using the RTL-SDR to quickly switch between frequencies and combine the outputs. It is similar to how rtl_power works.
With RTL-WideSpectrum and Radio-Sky Spectrograph, Raydel was able to capture this solar burst shown below which occurred between 28-48 MHz.
The post New method for generating wideband spectograph’s with Radio-Sky and an RTL-SDR appeared first on rtl-sdr.com.
Back in 2013 we posted about Juha Vierinen’s project in which he created a passive radar system from two RTL-SDR dongles, two Yagi antennas, and some custom processing code. Passive radar can be used to detect flying aircraft by listening for signals bouncing off their fuselage and can also be used to detect meteors entering the atmosphere. The radar is passive because it does not use a transmitter, but instead relies on other already strong transmitters such as FM broadcast radio stations. Juha writes:
A passive radar is a special type of radar [that] doesn’t require you to have a transmitter. You rely on a radio transmitter of opportunity provided by somebody else to illuminate radar targets. This can be your local radio or television station broadcasting with up to several megawatts of power.
His previous write up was brief, but now over on Hackaday Juha has made a detailed post about his RTL-SDR passive radar project. In the post he explains what passive radar is, shows some examples of his and others results, shows how it can be done with an RTL-SDR dongle, and finally briefly explains the signal processing required. In his next post Juha aims to go into further detail on how passive radar works in practice.
Below we show a video that shows an example of one of his passive radar tests that was performed with a USRP software defined radio and two Yagi antennas.
This video shows a lot of airplanes around the New England area detected using a simple passive radar setup, consisting of: one USRP and two yagi antennas, a quad core linux PC. Every now and then an occasional specular meteor echo is observed too.
In his other tests shown on YouTube Juha also used two RTL-SDR dongle’s with a shared clock and was able to get similar results.
The post Building a Passive Radar System with RTL-SDR Dongles appeared first on rtl-sdr.com.
Adam 9A4QAV is mostly known as the manufacturer of the popular LNA4ALL, a low cost low noise amplifier which is often used together with the RTL-SDR to improve reception of weak signals. He also sells an ADS-B bandpass filter and an ADS-B antenna, the latter of which we reviewed in a previous post.
Now Adam has come out with two new RF bandpass filters which are for sale. RF filters are used to block unwanted interference from other strong signals which can cause trouble, especially with low cost receivers such as the RTL-SDR.
The first new filter that he has developed is for FLARM (FLight Alarm System). FLARM broadcasts at 868 MHz and is a protocol similar to ADS-B. It is used by Gliders and some Helicopters for collision avoidance. It is possible to decode FLARM with an RTL-SDR which allows you to track gliders on a map, as discussed in one of our previous posts.
The second filter is for amateur radio astronomers who wish to detect the Hydrogen Line at 1420 MHz. Hydrogen molecules in space occasionally emit a photon at 1420 MHz. A single emission can’t be easily detected, but space and the galaxy is full of Hydrogen and the net result is an observable RF power spike at 1420 MHz. This can be detected with a high gain antenna, LNA, RF filter and radio like the RTL-SDR. The Hydrogen line can be used to measure things like the rotation and number of arms in our galaxy. Filters are very important for radio astronomy work as man made interference can easily drown out the relatively weak cosmic signals.
Adam sells all his fully assembled filters for 20 euros, plus 5 euros worldwide shipping.
The post Some new RF filters from Adam 9A4QV appeared first on rtl-sdr.com.
Recently Dr. Daniel Kaminski wrote into RTL-SDR.com to let us know about two very interesting new SDR# plugins that he has developed to use with the RTL-SDR dongle. The first plugin is called “Passive Radar”. Passive Radar allows you to use an existing strong transmitter such as an FM station to detect reflections from things like aircraft and meteors. Dr. Kaminski writes about his plugin:
The first one is passive radar which bases on signal from one dongle. The ambiguity function is the same as in advanced projects with the difference that the one I implemented is self-correlated one instead of cross-correlate one used for 2 dongles projects. In internet can be found that such solution theoretically can works. If the reflected signal is comparable in strength to the reflected one. This plugin is still until development.
In the future he hopes to be able to support two dongle passive radar as well.
The second plugin is called “IF Average”. This plugin allows the IF signal to be averaged which is useful for radio astronomy projects such as detecting the Hydrogen line. He writes:
The second plugin which is finished is for IF signal averaging. It is important in case of radio-astronomical observations. It allows to cumulate signals (up to 10000 samples in real time), present them in friendly way and save for further work.
The post Two New SDR# Plugins for Passive Radar and IF Signal Averaging appeared first on rtl-sdr.com.
At the recent 2015 Society of Amateur Radio Astronomers (SARA) Conference Ciprian Sufitchi (N2YO) presented a paper titled “Detecting meteor radio echoes using the RTL/SDR USB dongle” (pdf). His paper introduces the RTL-SDR, the theory behind forward scatter meteor detection as well as the practical application of the RTL-SDR to meteor detection. Ciprian summarizes meteor scatter as the following:
When a meteor enters the Earth’s upper atmosphere it excites the air molecules, producing a streak of light and leaving a trail of ionization (an elongated paraboloid) behind it tens of kilometers long. This ionized trail may persist for less than 1 second up to several minutes, occasionally. Occurring at heights of about 85 to 105 km (50-65 miles), this trail is capable of reflecting radio waves from transmitters located on the ground, similar to light reflecting from a mirrored surface. Meteor radio wave reflections are also called meteor echoes, or pings.
In the paper he explains how analog TV transmissions are the best for meteor scatter, but unfortunately these been discontinued within the USA. Instead he has been able to use analog TV transmitters from Canada, who still transmit this type of signal. He shows that about half of the USA could use the transmitter he is using for meteor scatter, which is based in Ontario, Canada.
Ciprian is also running a very cool live meteor detection stream on his website at livemeteors.com. His setup is located in the DC Metropolitan area and uses a directional Yagi antenna pointed at the Canadian analog TV tower which is broadcasting at 55.237 MHz. The receiver is an RTL-SDR dongle coupled with SDR# and the ARGO software.
The post Detecting meteor radio echoes using the RTL-SDR USB dongle appeared first on rtl-sdr.com.
