Off Grid Data Comms with a Raspberry Pi

Discussion in 'Amateur Radio News' started by OH8STN, Dec 11, 2019.

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  1. OH8STN

    OH8STN Ham Member QRZ Page

  2. KQ6XA

    KQ6XA Ham Member QRZ Page

    A very effective video of HF portable ham radio, filmed in the Arctic with wood fires, snow, and ice all around.

    Quite a good argument for the modular raspberry pi computer and accessories as the go bag unit, too.

    It shows how the use of weak signal HF messaging/ HF networking like JS8call is changing the realm of possibilities for operators.
    QRP-level text networking communication combined with positioning and selective calling is a powerful combination.
     
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  3. OH8STN

    OH8STN Ham Member QRZ Page

    Thanks Bonnie.
    It sounds so much better when you put it like that. There's still a lot of work to do. This field test was definitely a successful proof-of-concept. Now I need to do two more things. First a solar generator for the 817/818, a small one. One which fits perfectly under the rig, and is secured there with industrial velcro. After that, I'll turn my attention to an enclosure for the entire kit. I've ordered some leather for that. The goal is making a form fitting leather case, with a flap for front panel access to the radio. If this can be pulled off, it'll look like the integrated Comms kit I'm trying to achieve. I'll do this for the 891 as well. This will protect the wires between the radio, Raspberry Pi and 10 watt amplifier. It'll be less protection than the Pelican case, but it'll also be lighter and more portable. I can always put it in a dry bag.
    It's always awesome to get your feedback. It's like a motivation bomb to keep moving forward.
    73
    Julian oh8stn
     
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  4. W4NNF

    W4NNF XML Subscriber QRZ Page

    I'm not usually very interested in prepper videos, but this one was very well done. Thanks, OM.
     
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  5. OH8STN

    OH8STN Ham Member QRZ Page

    The goal is always to make something interesting to a wider audience. Your comment was the best compliment you could have given. Thanks for that.
    73
    Julian oh8stn
     
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  6. KJ6KK

    KJ6KK Premium Subscriber QRZ Page

    The Rpi can suffer corruption when its power is interrupted. With its external power supply connections, what measures do you take to preclude power interrupt to the Rpi?
     
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  7. OH8STN

    OH8STN Ham Member QRZ Page

    That's true. I addressed this in the first video from this series, but can explain here briefly. Firstly I'm suggesting we don't use the standard USB connector to power the Raspberry Pi. It's prone to being pulled out inadvertently, leading to the very thing you mentioned in your comment, card corruption. To rather than using that USB connector, we tap the 5 volts and ground pins from the headers, routing them through an RF quiet buck converter. From the buck converter, wires snake out of the rear of the raspberry pi, terminating with Anderson powerpoles.
    Next there is a soft button connected to the pin headers, telling the raspberry pi to shut down nicely. It will close all running applications, and shut down the Raspberry Pi. A few seconds after pushing that button, power to the Raspberry Pi can be removed. The next time power is applied to the DC input, the Raspberry Pi will start up automatically. That's how it's set up a my system right now.
    Now because I'm kind of a redundancy not, I also carry an identical copy of the SD card running on the Raspberry Pi. In the unlikely event the SD card is corrupted, I can replace the Raspberry Pi SD card in seconds, getting right back on the air.

    I'm also experimenting with a device called the PiJuice hat. It's a ups for the Raspberry Pi. It has its own power source, and detects when powers to the Raspberry Pi has been removed. It will close all apps running on the Raspberry Pi, shutting the Raspberry Pi down correctly, even if external power is abruptly removed.

    Great question.
    73
    Julian oh8stn
     
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  8. N4GKS

    N4GKS Ham Member QRZ Page

    Very good video.
     
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  9. VA7UW

    VA7UW Ham Member QRZ Page

    Have a look at Hardened Power Systems. I had a QRP Ranger with Solar, with an 817. it was a perfect portable kit. Keith and the crew at Hardened Power are always coming up with great gear. Sometimes you have to wait for stock, and shipping, but the gear quality, and customer service is amazing. check them out!
    portableuniversalpower dot com
    /our-products/qrp-ranger/
     
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  10. OH8STN

    OH8STN Ham Member QRZ Page

    Thanks for the comment. I know HPS very well, having made the mistake of recommending them on the channel once before. HPS made excellent equipment for lead acid batteries and perhaps still does. Their first gen attempts into Lithium Iron Phosphate chemisty were a complete fail. No internal battery management system, cheap and unbalanced/unmatched chinese cells held together with hot-glue, RF noise, and poorly designed 3D printed enclosure were all enough reasons to put people off. Since then they are integrating Dakota Lithium cells in some of their gear. That was a good move for a company lacking lithium ion and lithium iron phosphate expertise in-house. This only leaves justification for the price. A good small capacity Dakota lithium pack comes in at around 100 bucks (starting) which is reasonable. Add an enclosure, chinese charge controller, some wire, switches, relays, most of which sourced from China ... and the HPS price is what it is. Personally, If I couldn't figure out how to build my on pack using many of the free online DIY Ham Radio portable power resources, I would just buy the Dakota Lithium pack, and put it inside a pelican case using my own switches, wires, fuse, relays, ... When one builds diy taking control of design, componet quality and component specification choices, it becomes impossible to justify the HPS price. HPS has beautiful gear, but they don't build reliable gear. Its not their fault though. Everyone is trying to compete with the Chinese invasion. Some compete through quality, others through higher price.

    73
    Julian oh8stn
     
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