I’m just waiting on a few more parts, but I will post my build and progress pics as I go. Plan is to have a mobile receiver that we can deploy around the airport to test different areas for optimum reception.
Expect updates over the coming weeks.
Current Parts List:
NooElec NESDR Mini 2 SDR & DVB-T USB Stick (22.95)
Sunforce 50022 5-Watt Solar Battery Trickle Charger (37.53)
Energizer 500W Power Inverter (32.63)
CanaKit Raspberry Pi 2 Complete Starter Kit (69.99) - includes case, SD card, wifi adapter
1090MHz ADS-B Antenna (44.95)
RF coaxial cable assembly N male to MCX male (6.50)
Husky Toolbox (14.97) - to hold all the pieces outside.
I can understand the use of a 12v photovoltaic system to collect and store the power, but would just use a simple regulator to get the 5v required by the PI see - ebay.com/itm/321958726878 - these will operate with a power source of about 8-20v.
I see no point in using the inverter or wall-wart power brick that comes in the Raspberry Pi kit.
For the WiFi there have been links set up to put the WiFi dongle at the focus of a re-purposed satellite dish that have operated at 20 miles range or so (using a pair of dishes & dongles).
It will be interesting to hear how this project goes.
This is purely an experiment that the airport is supporting as a way to supplement the Passur system we currently use. I’m sure there will be many phases of prototyping, and a fair bit of McGuyvering mixed with some luck to get it to work as intended.
The wi-fi connectivity around the field is actually quite good. For the different locations I picked out, I have a reliable internet signal and stable power. The solar powered unit is to see if it will be worth running power to different locations on the field.
The parts list doesn’t include the 12v battery as of yet, but as one user pointed out, yes that’s what the inverter is for. The solar panel does come with a built in regulator, but my interest is having these units run 24/7, requiring power storage. By my math (which may be a little fuzzy), the solar panel should produce enough power to fully recharge the battery with 8 hours of good daylight. Whether or not that’s the case, we’ll find out soon enough.
Updates will be sporadic, as I have other responsibilities here at the airport. I will definitely be documenting the process, as I’m using it for a case study for an eventual accreditation. I’m just lucky to be working where the management is open to the idea and willing to fund it.
@MMUOps Any update on this? I am looking at something similar. I was evaluating PoE, but for different reasons, this is not really possible for me. Which means fully autonomous. Wifi is not an issue neither. Power is my issue. Wind is not an option due to space constraints. Putting a large solar panel is not an issue though. Were you able to scope the size of the solar panels (in Watts) required to be able to power the Pi and recharge a battery? I was thinking of using a Pi Zero W for one, and a smaller 12v battery for 2 (like the eBike/scooter models, 12Ah or so).
If anyone can chime in as well, it would be great.
My solar setup is probably not the example you are looking for:
200W panel, 10A MPPT regulator, 2x 12V 40Ah AGM batteries wired for 24V.
What I will suggest is to use a regulator with a low voltage cutout., If the battery gets low (obviously) the power will get switched off - but, when the power comes back on, it will be crisp and the Pi should power up without problem.
A pi zero running wifi should use under 2W. Powering an RTLSDR dongle takes about 300mA or another 1.5W or so. If you assume an power budget of 5W, that should be plenty for continuous operation.
That gives a total of around 120Wh that you need to supply each day. If you are using a 12V battery, that means a continuous draw of just about 410mA ignoring any voltage converter losses. That’s approximately 5 Ah of battery capacity. That’s quite a conservative estimate, and in reality you probably won’t need quite that much.
You want sufficient solar capacity to maintain a battery at a healthy voltage, such that if you get a day or two of poor weather and low output it has enough reserve to keep operating. I’d estimate that you probably want something like a 20Ah or so battery. Solar panels do not put out anything like their rated maximum output when averaged over a day, but this varies hugely depending on where you are. Somewhere in higher latitudes will require a larger panel than somewhere where it’s consistently sunny, especially accounting for seasonal variation and short winter days.
It would probably be a good idea to use something like a Sleepy Pi 2, which can take a 5.5-30V input to power the pi and gives options for power monitoring and a RTC.
This article has some thoughts on powering a pi with a solar system.
Edit: Since this post, I have bought and installed a Dockerpi powerboard. This takes a ~12v DC input and feeds 5v to the pi via the pin header. It can supply up to 5A at 5V, so is plenty to power pi, dongles and an LNA.
Thanks @geckoVN and @caius. Much appreciated. I have reached out to the Raspberry Pi foundation for my project as I was looking at using the compute module, and expand my project to more use. With the Pi 4 and some future development, my project makes more sense when combined. This got me into rethinking a few things. So far, I have settled on the following: combining solar, wind and hydro electric generation. My power sources will be installed where it make sense (wind on the cliff, water and solar panels at the base along with the batteries. Power to be sent up to the Pi(s… I may use 2) via PoE. And internet via Wifi using a Yagi to the building 250 ft below. I rigged a quick test setup with batteries to make sure my concept could work, and works fine. With all of the power manage being on terra firma, I don’t have a space and weight constraint. A 50ft run of cat 6 ethernet to bring electricity and ethernet is now making a lot more sense to me/ Making the setup more stable and flexible. At the end of the pole would be the antennas, a camera case, and weatherproof case with the PI(s). It should be lightweight and slim enough to sustain high winds without too much problem. I will setup an empty box with water damage detection strips for a little while to confirm my setup makes sense in terms of location, anchoring, etc. While I am sourcing and planning the rest of the setup, this should provide valuable logistic information.
My second location is in the arctic, I will solely use wind and hydro as my power source there. Only difference other than that, would be that the internet link would go directly to the Pi instead of heavier box were batteries are to be located, and use a BBQ grill directional antenna, for a 3 mile link. I have a similar setup workin, so I know my internet access is not the concern here. anchoring in the mountain.
I’ll try to document my progress and setup for those interested.
