The Open Source OVI-40 SDR Transceiver

Thanks to various contributors for letting us know about the OVI-40, a new open source DIY SDR ham radio transceiver project that is now available for ordering. The OVI-40 appears to be a German project that is based on the mcHF transceiver. It is a standalone SDR transceiver (no PC required) with a frequency range of DC - 75 MHz. Most discussion appears to be happening in German on their forums, so it is a little difficult to get English information about it.

The kit has recently been released for preorder. The transceiver is a kit involving SMD soldering, but can be ordered fully soldered for 202 Euros (~$240 US) + taxes. The LCD screen is an additional 24 - 27 Euros. The kit without soldering done costs 112 Euros (~$132 US) + taxes.

The advertised details and specs are listed below:

OVI40-SDR is a transceiver which covers VLF...75MHz. It is mainly a DIY project - but all PCBs will also be available as soldered, aligned / programmed PCBs for all those, who do not have the skill to build a complex SMD project by themself or do not want it. OVI40-SDR will also be available as "only RX" and can be expanded with TX stages later.

Developer team takes inspirations from all existing commercial and DIY projects to get a SDR which combines possibly the best of all of them. But OVI40-SDR is not only a TRX - it is a philosophy. A community based working together, regardless of different countries, languages, religions, political systems - all are working together to get a very nice transceiver for themselfes and for others who are coming to the project later - wants to show, what people can reach if they are working together and do not struggle against each other. HAM radio always has connected the world - using the possibilities of the internet adds much more power for community working.

  • RX from VLF (~ a few KHz) ... 4m, possibly 2m Including
  • TX 160m ... 4m: 50W, 2200m, 630m and 4m (2m if Implemented): 10 ... 20mW SMA Out
  • continuosly tuned preselection
  • PA works using double LDMOSFET, independent BIAS adjusted. BIAS is internally Measured via A / D and can be set in menu Directly in [mA].
  • TX and RX mixer with very low capacity to minimize LO leakage
  • true RX QSD mixer using instrumental amplifiers
  • all internal Voltages (8V, 5V) are generated using well-shielded switching regulators. Additionally switching frequency is shifted via firmware so that never harmonics are present in the RX spectrum
  • included hardware for measuring antenna (sweep) using logarithmic amplifier
  • output of an independent selectable rf to SMA plug. I am experimenting to use this as a beacon WSPR Which can run parallel to radio
  • usage as possible network analyzer
The OVI-40 Kit Assembled
The OVI-40 Kit Assembled

14 comments

      • DF8OE

        Sorry – that is only a small part. You do not need common software. All is implemented in firmware. It will be “standalone”. And that is the base why mcHF and OVI40 *are SDR transceivers*… You can extract IQ -data for external use. But if you only want to listen SSB, AM, FM, CW – you do not need external software.

  1. DF8OE

    For clarification: OVI40 is an project which is “under development”. Not all neccessary parts which make a complete receiver (or transceiver) are released at the moment. Actually the “digital part” is finished and available. There is also an anlog part naccessary. This is not finished. Hopefully it will be released in first quarter of 2018. The analog part will consist of a “rf base PCB” where the stages (TX mixer, RX mixer, filtrs, PA and so on) can be plugged as “modules”. So you are able to modify or improve single stages without dropping the whole PCB. But again: the missing part is additionally needed for a working device! As long as the rf PCB is not available OVI40 UI PCB can be used to work with mcHF rf PCB. 30 pin header on OVI40 is pin compatible with 30 pin mcHF header. For all who are interested in a complete radio: please stay tuned.

    • pjotr

      The mcHF does up/downconversion with an analog switching mixer fed by an analog LO, followed by analog audio amplifiers, i.e. no software and no digital processing. The audio codec seems to connect audio in and outputs. The remaining stuff is for control, at least according to the block diagram.
      “complete signal processing is digital” would be a direct sampling TRX (no analog mixing) – the mcHF is far away from that

      Don’t get me wrong, your project is definitively interesting, but the term SDR seems to be a little bit misleading. Perhabs you can explain the difference between the mcHF and the OVI-40 SDR to make things more clear?

      • Bernie

        There still seems to be some DSP done in the microcontroller – which, theoretically, makes this radio an SDR. The audio codec is meant to replace the high performance ADC/DAC required for proper performance in HF.

      • DF8OE

        Audio codec provides IQ from mixer. All that is following (inculded demodulation, waterfall/scope, NR, NB, digital modes etc. is done in DSP.

        “direct conversion” is highest level – I call it “SDR class 1”
        “downmixing using 90° LO resulting in IQ signals” is one level down – I call it “SDR class 2”

        So it *is* a SDR radio. Schematics of digital part are already published – analog part included quadrature mixers, IQ-LO-generators, passband filters, TX amplifier, antenna switch is under construction and will be published if development has finished. Look at the schematics for further informations.

        mcHF and OVI40 are both using same SDR concept “class 2”. The differences between them at digital part are:
        – OVI40 uses STM32F7 (and later when available STM32H7), mcHF uses STM32F4
        – OVI40 uses two audio codecs, mcHF uses one
        – OVI40 has standard LCD 3.5″ @480×320, mcHF has 2.8/3.2″ @320×240
        – OVI40 provides much more buttons and GPIO as mcHF
        – OVI40 provides additional components such as RTC, SD-card reader +++

        • Bernie

          The STM32H7 will open a whole new world for experimenters, but big refactoring and simplification effort is required in the firmware side. Code readability is a show stopper for many people who want to volunteer to improve the DSP and the UI.

  2. pjotr

    They call it SDR. Would be interesting to know, what do they mean with SDR? To me, the mcHF looks more like an analog TRX with some processor/software providing the UI (GUI, knobs, audio etc.).

  3. DF8OE

    It is not correct that we only discuss in German. Discussions which are started in English are replied in English. But we cannot translate every discussion which started in German to English.

    Pages which are supplied in our WIKI can be translated manually to every language. We want to provide multilanguage support. Not as easy and eats much horse power 😉

  4. Max

    A community based working together, regardless of different countries, languages, religions, political systems – all are working together to get a very nice transceiver ….HAM radio always has connected the world – using the possibilities of the internet adds much more power for community working.
    Do they attend German language classes before working together?

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