Over on his YouTube channel dereksgc has uploaded a new video where he tests out a new yet to be released downconverter product from NooElec. A downconverter works by shifting high frequencies down into a range that can be received by the RTL-SDR. This makes it useful for receiving 2.2 GHz S-band satellite downlinks which is out of the tuning range of RTL-SDR dongles.
In his video dereksgc shows the new 'Ham-it-down' downconverter, and tests it with an LNA and S-band helix feed and dish. He shows that he is able to easily receive S-band telecommunications satellites without a dish, and with a dish he is able to receive the Coriolis and Chandrayaan-3 satellites.
The ham-it-down is expected to cost US$90 when released. We note that a much lower cost solution might be a commercial 2.2 GHz MMDS downconverter which also comes built in with an LNA and filtering and can be obtained from Aliexpress for less than US$20. Alternatively, the $90 might be better put towards a HackRF clone which is almost the same price and can receive S-band natively without the need for external downconverter.
Receiving 2.2 GHz with the RTL-SDR and Nooelec Ham It Down
The Electrosense network is an open source project aiming to deploy radio spectrum sensors worldwide. The idea is to help analyze and understand radio spectrum usage across the globe. Each sensor consists of an RTL-SDR, Raspberry Pi and an optional downconverter to receive the higher bands. If you're interested we wrote an overview of the project in a previous post.
Recently we received a sample of their Up/Downconverter expansion board which is used to expand the frequency range of the RTL-SDR to 0 MHz to 6 GHz. The converter board is entirely open source with the design files available on GitHub. The team note that they are also working on a V2 version which will be cheaper and smaller. The schematic and Firmware for the V2 is also available right now, but it is still under early testing and may change.
The board is not for sale, however you can apply to be considered for a free unit if you want to host your own Electrosense node and meet their criteria. If you do not you can still produce the board yourself. The team mention that the design is easily hand soldered, but there are a few difficult LGA components like the PLL, crystals and mixer which require a heat gun to solder. A the same time they also note that it is possible to get PCB manufacture and SMT assembly done for you for dirt cheap by PCB prototype companies like JLC PCB.
The Expansion Up/Downconverter Board
The converter board has 4-input SMA ports (only 3 are used) and one output port which connects to the RTL-SDR. The first input port is for the HF antenna input. This input connects to the circuit which converts 0 - 30 MHz into a higher frequency which can be received by the RTL-SDR. The second port is simply a pass through for the standard 24 MHz - 1.766 GHz range of a normal SDR. The third port is unused, and the fourth port connects the antenna to the downconverter circuit which allows us to receive from 1.766 GHz to 6 GHz.
Over on GitHub Ian Wraith has released his design and microcontroller code for a low cost 2.4 GHz downconverter circuit. A downconverter is a hardware device that shifts the signals that it receives into a lower frequency band. This is useful in the case of RTL-SDRs and Airspy SDRs, as their maximum frequency range is only 1.7 GHz. Ian's 2.4 GHz downconverter reduces those 2.4 GHz signals down to 1 GHz, which can then be received with his Airspy.
Rather than designing a circuit from scratch, Ian's design makes use of several very cheap Chinese evaluation/development boards that he found on eBay. It costs of a mixer board, oscillator board, and an STM32 development board for controlling the oscillator board via SPI. The whole set of hardware cost him less than £30 (~37 USD).
After spending some time working through the difficulties in programming the SPI interface on the STM32 board, he was able to get the downconverter circuit fully working. He notes that he's been able to receive WiFi, Zigbee, Bluetooth and ISM band signals at 2.4 GHz, as well as 3G and 4G cellular signals at 2.6 GHz.
Ian Wraith's Downconverter consisting of three off the shelf cheap Chinese eBay boards.
Thanks to Ohan Smit for submitting news of his newly released GUI for Outernet's moRFeus wideband signal generator. Ohan's GUI works in both Linux and Windows. The Windows release can be downloaded from the GitHub Releases page. With the GUI you can change the mode between Mixer/Generator, generate noise, run a sweep, turn the bias tee on/off and generate a CW message.
A few days ago we also posted about about a moRFeus GUI by "Lama Bleu" which has similar functions. Although it only appears to run in Linux, Lama Bleu's GUI can interface directly with GQRX.
moRFeus is still currently on sale at CrowdSupply for $149 for the next 19 hours from the time of this post. The price is expected to rise after.
Back in March we posted about the release of Outernet's moRFeus device which is a low cost wideband RF signal generator. Since then we've received a few emails from two readers who've received their units and have found some interesting hacks and have developed software for it.
First we have a submission from Ohan Smit who discovered a hack that allows moRFeus to work as a wideband noise generator by setting the LO to 5 GHz and the Mixer current to 3. Together with an Airspy and the Spectrum Spy software he was able to measure the response of a bandstop FM filter. Over on the forums he also shows screenshots of Python based control software that he's developed for controlling moRFeus.
moRFeus Generating Noise
Next we have a moRFeus Linux GUI created by "Lama Bleu". It can be used to access the same functions as via the moRFeus LCD screen, but is also has a few very useful features such as a step generator which allows a generated tone to sweep across the frequency spectrum. The moRFeus GUI can also connect to GQRX and sync with the LO frequency specified in the GQRX GUI for easy control. It should also be possible to implement a CW morse code generator with some scripts.
Outernet moRFeus GUI
Over on the forums Zoltan, one of moRFeus' designers also notes that it might even be possible to use moRFeus for WSPR modulation, although this isn't confirmed yet. It seems that moRFeus is shaping up to be a very useful tool for RF testing and experimentation. The device is currently still available on Crowd Supply for $149US with over 136 units sold so far.
During development of the Outernet project the engineering team developed several tools to help them in their RF testing. One tool that they created has now been developed further into a commercial product that they are calling 'moRFeus'. moRFeus is a small handheld RF signal generator and frequency mixer. It can be used to generate an RF tone at any frequency between 85 MHz - 6 GHz and to upconvert or downconvert signals via the mixer with an input/output frequency range between 30 MHz - 6 GHz. This type of tool is useful for people working with RF hardware as it can be used for testing and prototyping.
morRFeus is currently selling for US$149 over on CrowdSupply, and the units are ready to ship out soon. They note that the current price is a special, and that it may be increased in the future. We think that this is a fairly good deal considering that similar products can cost much more. If you are interested in the technical details the datasheet includes figures on phase noise and conversion losses. There is also a user guide that explains how the buttons work, and what each screen on the menu is for. The morRFeus press release reads:
Outernet launches sales for wideband frequency converter and signal generator with complete field-level configuration.
Today, Outernet announced the launch of moRFeus - a wideband (30MHz - 6GHz) frequency converter and signal generator with complete field-level configurability. The product is available on Crowd Supply for $149. The price will increase after the 30-day launch campaign.
The device has an LCD display and button interface for complete field-level configuration - from setting the LO frequency to toggling between mixer and generator mode, and more. It’s in a precision-milled all-aluminum enclosure for durability and aesthetics.
moRFeus was built for hams and hackers, people with a traditional amateur radio background, as well as a makers and researchers that are interested in RF experimentation. It was designed for easy integration into a wide variety of RF projects.
In mixer mode, moRFeus enables dynamic frequency up- and down-conversion. In generator mode, it is one of the most, if not the most, affordable tools to generate a stable +/-2.5 ppm CW signal. Additional information on features, specifications, and performance metrics can be found in the datasheet.
The team already has 100 units in stock and another 900 are going through final assembly and quality assurance in Chicago. The first 100 units will ship one week after launch and orders beyond the initial stock will ship within 30 days of the close of the campaign, or earlier.
Outernet has been working on novel RF projects since the founding of the company in 2014. moRFeus was developed because from an internal need for a wideband field-configurable frequency converter for testing purposes. The company identified a huge gap in the market for a solution that met the needs of others with similar problems add their own. Outernet’s founder describes the development process:
“The idea was hatched about a year ago because we needed an easy, quick way to dynamically up-and down-convert the various radios we were experimenting with for a new product. By the summer of 2017, we had our first prototype and functional firmware. The design still required some slight tweaking. The current version of moRFeus is its third iteration. Oddly enough, the last phase of the project, industrial design, ended up being the most time-consuming. We worked with a local designer/machinist with decades of experience to come up with a custom-made all-aluminum enclosure.”
For more information and to purchase moRFeus, visit Crowd Supply.
Furthermore the product features, description, and also some of the applications and use cases for moRFeus are quoted below:
Features
RF Input Frequency: 30MHz–6GHz
RF Output Frequency: 30MHz–6GHz
LO Frequency: 85MHz–5400MHz
Fractional-N Synthesizer
LO Step Size: 1.5–3Hz1
2.5 ppm precision TCXO
USB programmable
Generator/Mixer Function Toggle
Input IP3 +23dBm
Small, Portable Form Factor
Adjustable Mixer Bias Current
LCD Display With Backlight Feature
Button Control Interface
Dimensions: 88mm x 38mm x 68mm
Weight: 7.4 oz
Product Description
moRFeus is a 30MHz–6GHz programmable Fractional-N wideband frequency converter and generator designed for low spurious emissions and dynamic configuring of the LO frequency. moRFeus is designed for easy integration into popular RF environments using SMA connectors and is powered using an external micro-USB 5V supply. The LCD display and button interface provide a dynamic way to program the mixer LO frequency in the field with a step size of 1.5–3Hz.1 The device is USB programmable, enabling automatic operation from a PC (must be running Linux). Dynamic toggling between mixer and generator modes adds to field-level functionality. An optional bias voltage of 5V is available via RF choke to the mixer input to supply active antenna systems.
Applications
Wideband Radios
Distributed Antenna Systems
Diversity Receivers
Software Defined Radios
Frequency Band Shifters
Point-to-Point Radios
WiMax/LTE Infrastructure
Satellite Communications
Wideband Jammers
Remote Radio Heads
Frequency Up/Down Conversion
Automated Test Equipment (ATE)
Wireless Communication Systems
moRFeus Block Diagram
Review and Testing
The Outernet team sent us a moRFeus unit for testing a few days ago. It comes in a portable 3.5 x 2.7 x 1.5 inch (8.9 x 6.9 x 3.8 cm) conductive milled aluminum enclosure and weighs 7.4 ounces (210 grams). The construction is very solid, and should easily survive being thrown around in a carry bag, although we'd still advise caution as the LCD screen is not protected by a window.
The unit is powered via a standard micro USB port. After connecting a USB cable the unit immediately powers up shows a frequency selection screen on the LCD display. Five small buttons are used to control the interface, and we found it very easy to adjust the output frequency using these buttons.
Using the interface the unit can be switched between the "Generator" and "Mixer" modes. In the generator mode moRFeus simply generates a CW tone at the desired frequency. In the mixer mode moRFeus takes an input signal, mixes it with the generated tone and puts the result on the out port. Mixing a signal with a tone is the core concept behind devices like upconverters, downconverters and tuners. For example, by generating a mixing tone at 2 GHz with the moRFeus, we are able to view 2.4 GHz WiFi signals at 2.4 GHz - 2 GHz = 400 MHz.
In the screenshot below we set moRFeus to run in mixer mode with the LO frequency set at 2 GHz. This allows us to view an active WiFi signal at 2.475 GHz using an Airspy and the SpectrumSpy software. The Airspy can only tune up to 1.8 GHz by itself, so it can't view the WiFi band directly. Of course to use as a proper downconverter filtering is required to remove any images and interfering signals, but by being able to easily change the LO frequency you are able to move the signals around quite easily to avoid images or interference.
Unfortunately one limitation is that moRFeus' lowest input frequency is 30 MHz, so it can't be used to upconvert HF signals.
Viewing a 2.4 GHz WiFi signal on an Airspy by using moRFeus as a downconverter with LO set to 2 GHz.
moRFeus also works well as a standard RF signal generator, and we were able to get a clean CW tone on any frequency between 85 MHz - 6 GHz.
moRFeus as a RF signal generator
moRFeus also shows up a a device on the PC, and the team write that it is possible to control it programatically via Linux, however documentation for this does not exist yet although it is scheduled to be released later. We would love to see a sweep feature which should be possible with PC control.
In conclusion if you are looking for a low cost signal generator or mixer to use in your experimental RF projects, then moRFeus certainly does seem like a good deal. A tool like this is very handy to have in your RF kit.
Thank you to an anonymous contributor for sharing his experiences with trying to receive satellite TV beacons with his RTL-SDR. Satellite TV is typically up at 10.7 to 11.7 GHz which is far too high for an RTL-SDR to receive. So to receive these frequencies with the RTL-SDR he uses a satellite TV LNB (an LNB is essentially a downconverter and satellite dish feed), a DIY Bias T and a 90 cm dish. He writes:
Almost all television satellites have a special frequency for transmitting a beacon signal. The beacon signal is a reference signal with fixed frequency, power and [maybe] without modulation that is sent usually by satellites. One of the most important techniques used for satellite wave propagation studies is satellite beacon signal measurement. (http://eej.aut.ac.ir/article_433.html)
I used an universal LNB, DIY bias-T and a fixed 90cm dish pointed at 26 degrees East. By connecting 18 volts DC to LNB I am able to activate the 9750 Mhz local oscillator and horizontal operating mode of LNB.
Means that anything received with LNB between 10.7-11.7 GHz can be easily seen in 950-1950 MHz range, using RTL-SDR.
It is useful for measuring attenuation caused by heavy rain in Ku band or accurate dish positioning or even measuring frequency drift in LNB local oscillator caused by wind and temp change during a timespan.
It seems that the right signal is Eutelsat 21B and left Es'hail 1.
In picture 4 signal captured immediately after turning on LNB. but all others are captured after at least 5 hours of warming up.
MAYBE oscillator needs a stabilize time or temp change may caused the drift.
If you are interested in receiving these beacons, Daniel Estevez has also performed similar experiments with his RTL-SDR and an LNB as well, and has written about it on his blog.
Below we show some images of beacons shown in SDR# that the anonymous contributor received with his setup.
Over on his YouTube channel dereksgc has uploaded a new video where he tests out a new yet to be released downconverter product from NooElec. A downconverter works by shifting high frequencies down into a range that can be received by the RTL-SDR. This makes it useful for receiving 2.2 GHz S-band satellite downlinks which is out of the tuning range of RTL-SDR dongles.
In his video dereksgc shows the new 'Ham-it-down' downconverter, and tests it with an LNA and S-band helix feed and dish. He shows that he is able to easily receive S-band telecommunications satellites without a dish, and with a dish he is able to receive the Coriolis and Chandrayaan-3 satellites.
The ham-it-down is expected to cost US$90 when released. We note that a much lower cost solution might be a commercial 2.2 GHz MMDS downconverter which also comes built in with an LNA and filtering and can be obtained from Aliexpress for less than US$20. Alternatively, the $90 might be better put towards a HackRF clone which is almost the same price and can receive S-band natively without the need for external downconverter.
Receiving 2.2 GHz with the RTL-SDR and Nooelec Ham It Down
The Electrosense network is an open source project aiming to deploy radio spectrum sensors worldwide. The idea is to help analyze and understand radio spectrum usage across the globe. Each sensor consists of an RTL-SDR, Raspberry Pi and an optional downconverter to receive the higher bands. If you're interested we wrote an overview of the project in a previous post.
Recently we received a sample of their Up/Downconverter expansion board which is used to expand the frequency range of the RTL-SDR to 0 MHz to 6 GHz. The converter board is entirely open source with the design files available on GitHub. The team note that they are also working on a V2 version which will be cheaper and smaller. The schematic and Firmware for the V2 is also available right now, but it is still under early testing and may change.
The board is not for sale, however you can apply to be considered for a free unit if you want to host your own Electrosense node and meet their criteria. If you do not you can still produce the board yourself. The team mention that the design is easily hand soldered, but there are a few difficult LGA components like the PLL, crystals and mixer which require a heat gun to solder. A the same time they also note that it is possible to get PCB manufacture and SMT assembly done for you for dirt cheap by PCB prototype companies like JLC PCB.
The Expansion Up/Downconverter Board
The converter board has 4-input SMA ports (only 3 are used) and one output port which connects to the RTL-SDR. The first input port is for the HF antenna input. This input connects to the circuit which converts 0 - 30 MHz into a higher frequency which can be received by the RTL-SDR. The second port is simply a pass through for the standard 24 MHz - 1.766 GHz range of a normal SDR. The third port is unused, and the fourth port connects the antenna to the downconverter circuit which allows us to receive from 1.766 GHz to 6 GHz.
Over on GitHub Ian Wraith has released his design and microcontroller code for a low cost 2.4 GHz downconverter circuit. A downconverter is a hardware device that shifts the signals that it receives into a lower frequency band. This is useful in the case of RTL-SDRs and Airspy SDRs, as their maximum frequency range is only 1.7 GHz. Ian's 2.4 GHz downconverter reduces those 2.4 GHz signals down to 1 GHz, which can then be received with his Airspy.
Rather than designing a circuit from scratch, Ian's design makes use of several very cheap Chinese evaluation/development boards that he found on eBay. It costs of a mixer board, oscillator board, and an STM32 development board for controlling the oscillator board via SPI. The whole set of hardware cost him less than £30 (~37 USD).
After spending some time working through the difficulties in programming the SPI interface on the STM32 board, he was able to get the downconverter circuit fully working. He notes that he's been able to receive WiFi, Zigbee, Bluetooth and ISM band signals at 2.4 GHz, as well as 3G and 4G cellular signals at 2.6 GHz.
Ian Wraith's Downconverter consisting of three off the shelf cheap Chinese eBay boards.
Thanks to Ohan Smit for submitting news of his newly released GUI for Outernet's moRFeus wideband signal generator. Ohan's GUI works in both Linux and Windows. The Windows release can be downloaded from the GitHub Releases page. With the GUI you can change the mode between Mixer/Generator, generate noise, run a sweep, turn the bias tee on/off and generate a CW message.
A few days ago we also posted about about a moRFeus GUI by "Lama Bleu" which has similar functions. Although it only appears to run in Linux, Lama Bleu's GUI can interface directly with GQRX.
moRFeus is still currently on sale at CrowdSupply for $149 for the next 19 hours from the time of this post. The price is expected to rise after.
Back in March we posted about the release of Outernet's moRFeus device which is a low cost wideband RF signal generator. Since then we've received a few emails from two readers who've received their units and have found some interesting hacks and have developed software for it.
First we have a submission from Ohan Smit who discovered a hack that allows moRFeus to work as a wideband noise generator by setting the LO to 5 GHz and the Mixer current to 3. Together with an Airspy and the Spectrum Spy software he was able to measure the response of a bandstop FM filter. Over on the forums he also shows screenshots of Python based control software that he's developed for controlling moRFeus.
moRFeus Generating Noise
Next we have a moRFeus Linux GUI created by "Lama Bleu". It can be used to access the same functions as via the moRFeus LCD screen, but is also has a few very useful features such as a step generator which allows a generated tone to sweep across the frequency spectrum. The moRFeus GUI can also connect to GQRX and sync with the LO frequency specified in the GQRX GUI for easy control. It should also be possible to implement a CW morse code generator with some scripts.
Outernet moRFeus GUI
Over on the forums Zoltan, one of moRFeus' designers also notes that it might even be possible to use moRFeus for WSPR modulation, although this isn't confirmed yet. It seems that moRFeus is shaping up to be a very useful tool for RF testing and experimentation. The device is currently still available on Crowd Supply for $149US with over 136 units sold so far.
During development of the Outernet project the engineering team developed several tools to help them in their RF testing. One tool that they created has now been developed further into a commercial product that they are calling 'moRFeus'. moRFeus is a small handheld RF signal generator and frequency mixer. It can be used to generate an RF tone at any frequency between 85 MHz - 6 GHz and to upconvert or downconvert signals via the mixer with an input/output frequency range between 30 MHz - 6 GHz. This type of tool is useful for people working with RF hardware as it can be used for testing and prototyping.
morRFeus is currently selling for US$149 over on CrowdSupply, and the units are ready to ship out soon. They note that the current price is a special, and that it may be increased in the future. We think that this is a fairly good deal considering that similar products can cost much more. If you are interested in the technical details the datasheet includes figures on phase noise and conversion losses. There is also a user guide that explains how the buttons work, and what each screen on the menu is for. The morRFeus press release reads:
Outernet launches sales for wideband frequency converter and signal generator with complete field-level configuration.
Today, Outernet announced the launch of moRFeus - a wideband (30MHz - 6GHz) frequency converter and signal generator with complete field-level configurability. The product is available on Crowd Supply for $149. The price will increase after the 30-day launch campaign.
The device has an LCD display and button interface for complete field-level configuration - from setting the LO frequency to toggling between mixer and generator mode, and more. It’s in a precision-milled all-aluminum enclosure for durability and aesthetics.
moRFeus was built for hams and hackers, people with a traditional amateur radio background, as well as a makers and researchers that are interested in RF experimentation. It was designed for easy integration into a wide variety of RF projects.
In mixer mode, moRFeus enables dynamic frequency up- and down-conversion. In generator mode, it is one of the most, if not the most, affordable tools to generate a stable +/-2.5 ppm CW signal. Additional information on features, specifications, and performance metrics can be found in the datasheet.
The team already has 100 units in stock and another 900 are going through final assembly and quality assurance in Chicago. The first 100 units will ship one week after launch and orders beyond the initial stock will ship within 30 days of the close of the campaign, or earlier.
Outernet has been working on novel RF projects since the founding of the company in 2014. moRFeus was developed because from an internal need for a wideband field-configurable frequency converter for testing purposes. The company identified a huge gap in the market for a solution that met the needs of others with similar problems add their own. Outernet’s founder describes the development process:
“The idea was hatched about a year ago because we needed an easy, quick way to dynamically up-and down-convert the various radios we were experimenting with for a new product. By the summer of 2017, we had our first prototype and functional firmware. The design still required some slight tweaking. The current version of moRFeus is its third iteration. Oddly enough, the last phase of the project, industrial design, ended up being the most time-consuming. We worked with a local designer/machinist with decades of experience to come up with a custom-made all-aluminum enclosure.”
For more information and to purchase moRFeus, visit Crowd Supply.
Furthermore the product features, description, and also some of the applications and use cases for moRFeus are quoted below:
Features
RF Input Frequency: 30MHz–6GHz
RF Output Frequency: 30MHz–6GHz
LO Frequency: 85MHz–5400MHz
Fractional-N Synthesizer
LO Step Size: 1.5–3Hz1
2.5 ppm precision TCXO
USB programmable
Generator/Mixer Function Toggle
Input IP3 +23dBm
Small, Portable Form Factor
Adjustable Mixer Bias Current
LCD Display With Backlight Feature
Button Control Interface
Dimensions: 88mm x 38mm x 68mm
Weight: 7.4 oz
Product Description
moRFeus is a 30MHz–6GHz programmable Fractional-N wideband frequency converter and generator designed for low spurious emissions and dynamic configuring of the LO frequency. moRFeus is designed for easy integration into popular RF environments using SMA connectors and is powered using an external micro-USB 5V supply. The LCD display and button interface provide a dynamic way to program the mixer LO frequency in the field with a step size of 1.5–3Hz.1 The device is USB programmable, enabling automatic operation from a PC (must be running Linux). Dynamic toggling between mixer and generator modes adds to field-level functionality. An optional bias voltage of 5V is available via RF choke to the mixer input to supply active antenna systems.
Applications
Wideband Radios
Distributed Antenna Systems
Diversity Receivers
Software Defined Radios
Frequency Band Shifters
Point-to-Point Radios
WiMax/LTE Infrastructure
Satellite Communications
Wideband Jammers
Remote Radio Heads
Frequency Up/Down Conversion
Automated Test Equipment (ATE)
Wireless Communication Systems
moRFeus Block Diagram
Review and Testing
The Outernet team sent us a moRFeus unit for testing a few days ago. It comes in a portable 3.5 x 2.7 x 1.5 inch (8.9 x 6.9 x 3.8 cm) conductive milled aluminum enclosure and weighs 7.4 ounces (210 grams). The construction is very solid, and should easily survive being thrown around in a carry bag, although we'd still advise caution as the LCD screen is not protected by a window.
The unit is powered via a standard micro USB port. After connecting a USB cable the unit immediately powers up shows a frequency selection screen on the LCD display. Five small buttons are used to control the interface, and we found it very easy to adjust the output frequency using these buttons.
Using the interface the unit can be switched between the "Generator" and "Mixer" modes. In the generator mode moRFeus simply generates a CW tone at the desired frequency. In the mixer mode moRFeus takes an input signal, mixes it with the generated tone and puts the result on the out port. Mixing a signal with a tone is the core concept behind devices like upconverters, downconverters and tuners. For example, by generating a mixing tone at 2 GHz with the moRFeus, we are able to view 2.4 GHz WiFi signals at 2.4 GHz - 2 GHz = 400 MHz.
In the screenshot below we set moRFeus to run in mixer mode with the LO frequency set at 2 GHz. This allows us to view an active WiFi signal at 2.475 GHz using an Airspy and the SpectrumSpy software. The Airspy can only tune up to 1.8 GHz by itself, so it can't view the WiFi band directly. Of course to use as a proper downconverter filtering is required to remove any images and interfering signals, but by being able to easily change the LO frequency you are able to move the signals around quite easily to avoid images or interference.
Unfortunately one limitation is that moRFeus' lowest input frequency is 30 MHz, so it can't be used to upconvert HF signals.
Viewing a 2.4 GHz WiFi signal on an Airspy by using moRFeus as a downconverter with LO set to 2 GHz.
moRFeus also works well as a standard RF signal generator, and we were able to get a clean CW tone on any frequency between 85 MHz - 6 GHz.
moRFeus as a RF signal generator
moRFeus also shows up a a device on the PC, and the team write that it is possible to control it programatically via Linux, however documentation for this does not exist yet although it is scheduled to be released later. We would love to see a sweep feature which should be possible with PC control.
In conclusion if you are looking for a low cost signal generator or mixer to use in your experimental RF projects, then moRFeus certainly does seem like a good deal. A tool like this is very handy to have in your RF kit.
Thank you to an anonymous contributor for sharing his experiences with trying to receive satellite TV beacons with his RTL-SDR. Satellite TV is typically up at 10.7 to 11.7 GHz which is far too high for an RTL-SDR to receive. So to receive these frequencies with the RTL-SDR he uses a satellite TV LNB (an LNB is essentially a downconverter and satellite dish feed), a DIY Bias T and a 90 cm dish. He writes:
Almost all television satellites have a special frequency for transmitting a beacon signal. The beacon signal is a reference signal with fixed frequency, power and [maybe] without modulation that is sent usually by satellites. One of the most important techniques used for satellite wave propagation studies is satellite beacon signal measurement. (http://eej.aut.ac.ir/article_433.html)
I used an universal LNB, DIY bias-T and a fixed 90cm dish pointed at 26 degrees East. By connecting 18 volts DC to LNB I am able to activate the 9750 Mhz local oscillator and horizontal operating mode of LNB.
Means that anything received with LNB between 10.7-11.7 GHz can be easily seen in 950-1950 MHz range, using RTL-SDR.
It is useful for measuring attenuation caused by heavy rain in Ku band or accurate dish positioning or even measuring frequency drift in LNB local oscillator caused by wind and temp change during a timespan.
It seems that the right signal is Eutelsat 21B and left Es'hail 1.
In picture 4 signal captured immediately after turning on LNB. but all others are captured after at least 5 hours of warming up.
MAYBE oscillator needs a stabilize time or temp change may caused the drift.
If you are interested in receiving these beacons, Daniel Estevez has also performed similar experiments with his RTL-SDR and an LNB as well, and has written about it on his blog.
Below we show some images of beacons shown in SDR# that the anonymous contributor received with his setup.
Last year KD0CQ discovered that the SUP-2400 is a cheap $5 – $10 DirecTV (US satellite TV) module which can be hand modded into a downconverter for the RTL-SDR. A downconverter allows you to listen to frequencies above the maximum frequency range of the RTL-SDR by converting frequencies down into a range receivable by the RTL-SDR (or of course any other SDR). The modified SUP-2400 allows to you listen up to just over 4 GHz.
The SUP-2400 modification is moderately involved and requires soldering and desoldering SMD pieces, so this product is great for anyone who just wants a cheap and low cost downconverter which is ready to go. And at $25 USD it’s still very good value. Shipping within the USA is $7.75, and internationally it is about $13.50.
