I recently started an open-hardware project based on my RF work for the past several years.  Although I was targeting challenging real-time data collection in a tree-fruit orchard envrionment, UAV telemetry seems like a very good match for the design due to the inherent attributes of Low-latency and High reliability.  This modem is very similar to the performance characteristics of something like the original MHX910 from Microhard Systems.  Let me know what you think.

----------- from the project page ---------------



Project Development Site For Valhalla Wireless OpenFHSS. OpenFHSS is a community-based effort that includes schematic, eagle design files, BOM, gerbers, and firmware for a 902-928MHz ISM, 50-channel, FHSS frequency hopping spread spectrum modem.



  • High Performance, Long-Range Frequency Hopping Spread Spectrum Modem
  • Synchronous, Multi-Hop Repeater Chains
  • Ethernet Bridge Mode
  • Automatic, over-the-air firmware updates. Master updates all slaves simultaneously
  • 4uA MCU initiated sleep current
  • 2ppm stability for frequency and system timing reference.
  • Industrial quality enclosure, connectors
  • Real-Time Data Collection System with user defined scripts
  • LM3S6965 32-Bit Stellaris ARM-core MCU, CC1101 transceiver, CC1190 LNA/PA
  • Highly immune to multipath fading, interference
  • 5mS Channel Dwell Time
  • -107dBm sensitivity, 27.1dBm output power enables communications range in tens of kilometers. Depending on installation, ranges of >50km are easy to achieve
  • Applications include battery-powered data collection, Low-Latency Telemetry Links (UAVs), long-range internet communications. Quality Skype phone calls have been achieved with point-to-points links.
  • 230 kbps RF Data Rate
  • very low phase noise performance (see emc plots in images/emc_testing)

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  • @Todd

    I know a little bit (just a little) of RF design and I can state that this is a really nice work.

    You earned to be my RF idol of the month.

  • @bcr


    Thanks for the comments.

  • Todd, thanks for sharing all your hard work, I hope things go well and someone in the right position takes notice. I know only too well the difficulties of entrapreneurship.

  • Nice work.
  • Bill,

    Thanks for the comment.  I would love to see some results from those kind of tests.  I'll look forward to potential collaboration for your future projects.



  • I'd say everyone in the hobby world is jumping to zigbee just because of price, but in the professional world, we laugh at them. Last event that I attended that had mixtures of zigbee and freewave radios, the zigbees were getting crushed in performance by freewave.

    Like I said i'd love to support open source when I can. I'm too far along in my current project, but if you are still selling them in the future, expect to hear from me when I start my next one.
  • Bill,

    No Worries.   I'm sorry if my response sounded defensive.  My original plans for this project have not been going well this year so far.  I sincerely hope that opening up the design will turn out to be a good thing for everybody that is interested.  I made the decision early on in the design that I wanted to try to match the performance of the designs from Microhard and Freewave that I had the opportunity to work with over the years.  These radios are truly "cream of the crop".   Seems like everybody is going to zigbee and such things these days without any idea of what is really possible.

  • Todd,

    Just in case there was any misunderstood tone, I am fine with the jump coming from personal profit/dev cost, it just wasn't clear in your previous comment which is why I was asking.
  • Bill,

    that "jump" from $330 to $794 is how I plan to make a living.  I have been though numerous iterations of design and EMC testing (close to $10k for testing).  With the open design, you can manufacture this design yourself.  Maybe you can get the cost down by manufacturing overseas, etc.  By opening this up, I have essentially given up on making a living on my original business plan.   I hope by opening the design, I can help create an open community-based effort to get cost down, improve the design, expand the applications, and increase my chances for obtaining some new funding/jobs for efforts based on this design.

  • Todd,

    'Your cost' to the selling cost (330 to 794), what causes the jump? Did you mean "That did NOT include x-ray inspection, and final assembly"?

    I'm curious to see where your design goes and if it gets picked up for regular production. I work for the U.S. Navy building Unmanned Systems, and we always use Freewaves. We get 1 Watt 900s for about $1100 because Freewave wants to keep us as a costumer.

    I would like to see the money spent on supporting open source products like this, though it's tough to replace 'mission proven' hardware with new designs without just cause. Thankfully there's new regulations we have to follow were bids must go to 'disadvantaged business' (the PC way of saying small businesses) whenever possible and doesn't compromise product performance.
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