moRFeus: A Low Cost Wideband Signal Generator and Frequency Mixer

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
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.
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 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.

10 comments

  1. PE2BZ from the Netherlands

    Well, I ordered 2… One arrived yesterday 🙂 Quick test: My KiwiSDR ( 0-32 MHz) needed a downconverter. Set the moRFeus to 401 MHZ and connected the output to the KiwiSDR. Logper at the input, mixer current from 0 to 1 and there it goes 🙂 401 to 433 MHz on my websdr. Might need some highpass at the input,however up and running in 10 minutes.

    After one hour I removed the moRFeus from the KiwiSDR, and connected it to the output of my 25 mW ATV trasnmitter. Set the mixer frequency to 1090 MHz and did some amplifiying at the output to get 90 mW at 2385 MHz 🙂 See, I am happy with it 🙂

  2. Karl-Heinz Schaefer

    Hello,
    I have got my LimeSDR a few days ago.
    I use the LimeSDR ( v1.4s ) with the SDRConsoleV3.
    How can I switch between the Coaxial RF ( U.FL ) Connectors RX1 ( H , L , W )
    and RX2 ( H , L , W ) ?
    In the SDRConsoleV3 — Home — RX Antenna , I can switch between None , H , L , W
    but always the connectors RX1_H , RX1_L and RX1_W are connected.

    How can I switch to RX2_H , RX2_L and RX2_W ?

    Best Regads

    Karl-Heinz

  3. Why am I thinking of the HackRF ?

    “RF Input Frequency: 30MHz–6GHz
    RF Output Frequency: 30MHz–6GHz
    LO Frequency: 85MHz–5400MHz”
    The above information instantly made me think of the RFFC5071/RFFC5072 chip (“wideband synthesizer/VCO with integrated 6GHz Mixer” which is used as the first stage mixer in the HackRF One, if the input signal is either side of the IF, otherwise it is bypassed):

    My guess is that inside the box is an ATmega chip which is driving the back lit LCD, the 5 input switches are connected to GPIO pins and finally they are bit banging the proprietary 3-wire (or 4-wire) serial bus protocol using GPIO pins to modify the register maps in the rffc5072.

    I waited until they were fully funded, before I talked about what I think is inside the box, unfortunately they did set their funding goal at $1. The product still is value for money, the rffc5072 chip alone in low quantity (up to 24) is $21.31 each direct from Qorvo. And when you factor in the cost of a custom milled aluminum enclosure, you could not make such a polished item cheaper yourself, especially with the time required to write all the source code, since moRFeus appears to be closed source.

    Oh and if you look up page 3 of the datasheet for the RFFC5072 chip and compare the Phase noise to that of the moRFeus device they are almost identical.

    • Psynosaur

      Heya

      i will pop open my unit when I get home today and let out all the secrets.

      For those that need more information on the unit and current developments check out the outernet forums!

      Cheers

  4. G1RNB

    What intrigues me about this project is that they appear to be addressing the noise issues that plague most of these fractional synth’s for use as LO’s.

    A high quality variable LO – especially to 6GHz- is an extremely useful tool indeed and until very recently was almost like a tune-able band-pass filter lay somewhere in our RF future…yet to be designed.

    This is a good development and one I shall be watching and hopefully investing.

    As for the HF issue, bolt an Arduino to a Si5351a, get the code and you have DC-200MHz, signal generator and sweep, but good luck with the phase noise.

    Which brings me full circle to a tune-able band-pass filter.

    You see they are both required for an mixer quality LO.

    Cheers everyone

    G1RNB

  5. Alyx

    literally 2 days after getting a PLL board off ebay to generate a 4.8ghz tone … and it cost more than this xP

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