2nd October 2022 - It is my goal to build a fully-automated station for the reception of APT and LRPT weather satellite images. The station will work on its own and store images for later extraction, possibly with a high-gain WiFi link for network access. This page will serve as a landing page for everything related to this project, from useful links with good information to my own notes as I think things out.
I know how to do all of the software and cabling and frequently do this out in the field with a laptop and temporary setup, but the power and antenna/mount for a permanent, hardy setup is a bit difficult for me yet as I’m not very DIY-minded. My other projects are very “hacked together” as you may have seen from my various articles on the Wiki.
Literally no experience with this, but it seems easy from this guide - I need a PiJuice, a solar panel and a regular LiPo battery with the standard 2 or 3 leads. I do have an old USB power bank I could use sitting there doing nothing, but it only has USB inputs/outputs and no 2/3 pin lead. I could disassemble it maybe and get at the insides, but that’s scary.
Other people are doing this with 12 Volt LNAs, so need a higher voltage battery and solar panel setup, plus a voltage converter to get it down to 5V AND a solar panel controller that will do 12V. Having said that most of the higher rated panels use 12V, so I would need to go this route if I can’t find a 5V panel of a decent rating.
Hopefully I just mount the PiJuice HAT, connect the battery and panel setup, and hopefully it’ll produce enough juice. The USB output current limit on the RPi shouldn’t be an issue hopefully, as I’ve used them off battery with a few gadgets like RTL sticks in before off a full 2A supply.
If there are any issues with current I may need a powered USB hub, which adds complexity and potential RFI sources. I would also like to know if there’s an alternative to the rather expensive PiJuice for all of this.
On the non-RF side it’ll be a RPi 3B or 4, depending on what’s available. A 3B will do it just fine if I can still get them and will run cooler, but Pis are *very* sold out. I’ll maybe need a WiFi dongle with an external antenna socket to try and reach the long range to my living room router (this is a stretch goal really).
For the RF side I’ll need a receiver, and I have a spare RTL-SDR stick I can use for it. I also have a low-noise amplifier/bandpass filter for 137-138 MHz that will work over bias-T or USB, so I have options depending on where I mount the enclosure box with respect to the feedpoint of the antenna. The LNA/BPF should be close to the antenna feedpoint, requiring a bias-T (or a 1-2M micro USB lead, i guess…), but I’d like to put the box closer to the ground so if I put the amp/filter in the enclosure I can use USB easily - but how much will that degrade performance?
I may want to add some buttons or indicator LEDs to the outside, to shut things down or indicate a problem. These will need to visible outside and be waterproofed.
The smaller the install the better, the more automated the better, and the less work for the SD card the better. I’ll aim to optimise this setup, starting with the base install of the OS and script and then make changes or modifications as required.
Another useful modification is to make the RPi use as little power as possible by disabling onboard peripherals.
A test of my DIY skills, for decent protection the enclosure should be rated highly on the IP scale, I’m thinking IP67/68. This gets pricey, so I need to make sure I make the build relatively small and compact to save money.
I think I can use Velcro or cable ties and pads to hold most of it together on the inside.
Some relevant links and ideas will go in here as a scratchpad, as well as places to blatantly steal from..
There is prior art for this idea, and there’s two good ones here: