Over on YouTube Corrosive from the SignalsEverywhere channel has uploaded a new video showing us how you can make a DIY upconverter using a HackRF as a signal source and a cheap $10 RF Mixer. An upconverter converts lower frequencies into higher frequencies. For example, an upconverter is commonly used to convert HF signals into VHF, so that VHF/UHF only SDRs can receive HF.
In the video he uses the HackRF as a local oscillator source, a cheap RF mixer on a breakout board, and an Airspy as the receiver. In most circumstances if you needed and upconverter you'd just purchase one like the Ham-it-up, or the Spyverter for ~$40. However the interesting advantage of using a versatile signal generator like the HackRF is that it results in an upconverter that can upconvert HF to almost any frequency. Even without any filtering (which is recommended to remove signal images), Corrosive fings that he has excellent HF reception.
This video is an excellent way to learn about how upconverters work.
HackRF and RF Mixer = DIY RTL SDR Up-converter | Basics of the Passive ADE Mixer
moRFeus is a low cost wideband signal generator and frequency mixer. It can be used to generate a tone anywhere from 85 MHz to 5400 MHz, and can also be used as a frequency mixer, allowing you to implement upconverters and downconverters. In past posts we've reviewed and seen it being used as a PC based signal generator with open source GUI's, downconverter, CW generator, and most recently as a tracking generator for measuring filters and antenna VSWR.
Currently Outernet are having a half price sale on the moRFeus. Normally it's US $199, but now with the coupon code "rtlsdrblog" it's only US $99. The sale only lasts until Saturday 09 June 2018, so get in fast if you want one.
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.
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.
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:
RF Input Frequency: 30MHz–6GHz
RF Output Frequency: 30MHz–6GHz
LO Frequency: 85MHz–5400MHz
LO Step Size: 1.5–3Hz1
2.5 ppm precision TCXO
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
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.
Distributed Antenna Systems
Software Defined Radios
Frequency Band Shifters
Remote Radio Heads
Frequency Up/Down Conversion
Automated Test Equipment (ATE)
Wireless Communication Systems
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.
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 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.
The LimeSDR is a new transmit capable software defined radio with a 100 kHz – 3.8 GHz frequency range, 12-bit ADC and 61.44 MHz bandwidth which is currently seeking crowdfunding. At the time of this post there is about four days left to reach the $500k goal, and it is only 80% funded. To try and reach their funding goal they have released another batch of discounted units which cost only $249 USD. After the crowd funding campaign the price will rise to $289/$299 USD. If the LimeSDR is not funded in time, they write that the project will unfortunately be put on hold and it’s future may be uncertain. We believe that this product is shaping up to be a very good TX/RX capable SDR, like the HackRF and bladeRF, but much better overall and for the same or even lower price.
Recently they also released some new updates that show off some LimeSDR features. In a post previously featured on our blog beta tester Alexandru showed how he was able to get the LimeSDR to transmit DVB-S2 HDTV. In later updates they showed how the LimeSDR can be used to:
Create a Vector Network Analyzer. With the help of a directional coupler the LimeSDR can also be turned into a Vector Network Analyzer to measure parameters such as gain, insertion loss, return loss and VSWR.
Build a remote radio head. By mounting the LimeSDR near the antenna and streaming the data back over an IP link, coax feed losses can be eliminated.