Mobile pi
outline
A portable raspberry pi work-bench.[note 1]
power budget
| model | idle power Watts |
max power Watts |
max current mA |
supply Volts |
|---|---|---|---|---|
| pi Zero W [note 3] | 0.5 | 1.2 | 240 | 5 |
| pi 3B+ | 1.9 | 5.1 | 1020 | 5 |
| pi 4B | 2.7 | 6.4 | 1280 | 5 |
| pi 5 2GB | 2.4 | 7.6 | 1520 | 5 |
| Flightaware Pro Stick Plus SDR | 2.5? | 2.5 | 500 | 5 |
| Neo 6M | 0.015 | 0.115 | 38 | 3 |
| Neo 8M | 0.015 | 0.063 | 21 | 3 |
| LTE router | TBA | ? | ? | 12 |
| 1090 MHz LNA | 45 | 150 | 3 |
battery capacity
I will be using recycled high capacity Panasonic MH12210 (18650) Lithium cells with a typical capacity of 3100 mAH when fully charged.
The proposal is to use a set of 6 cells in the 3S 2P configuration (on the one BMS) - which will yield approximately 18600 mAH down converted to 5 volts for the pi (223.2 WH not counting the LTE Router that I will need to measure after it arrives ) - let's assume an additional 1000 mA for approximately 5 hrs running time. We will see what efficiency is actually available in the power supply arrangement by trial, measuring how long the pi can keep working.
If the draw is 1500 mAH for the pi, and assuming 1000 mA for the LTE router [note 5] and assuming the power supply is 85% efficient, we would see a running time of 0.85 * 18600 / 2500 => 5h 15m. I will report just how long the device can operate on a fully charged set of batteries after it is built. It is almost like making your own laptop - but it will be headless and support a multitude of WiFi devices.
The idea will be to place it on the hatself of the aeroplane and to have the 4G / 5G antennas underneath the wing section inside the plastic belly out of the airflow. Some experimentation will be necessary with antenna mounts, and maybe some slot antennas can be designed and glued to the plastic belly and fed from a mounted SMA fitting? [note 6]
performance
The raspberry pi 3B+ with WiFi and 1GB of RAM is more than adequate to run overlayfs, gpsd, piaware, dump1090, fr24feed, ssh tunnels and all sorts of other applications.
- a pi 3B+ running at 30% at the home QTH covering YSCB (with limited antenna coverage) [note 7] [note 8]
- it hits about 40% CPU tracking aircraft at YSWG [note 9]
cat /proc/cpuinfo ... processor : 3 BogoMIPS : 38.40 Features : fp asimd evtstrm crc32 cpuid CPU implementer : 0x41 CPU architecture: 8 CPU variant : 0x0 CPU part : 0xd03 CPU revision : 4 Revision : a22082 Serial : 00000000720bc8f5 Model : Raspberry Pi 3 Model B Rev 1.2
components
Here is the list of components:
- GPS active external antenna (ordered 6)
- GPIO header
- raspberry pi 3B+ would work fine with 500 MB - 1 GB RAM is fine [note 11]
- a G4 / G5 LTE industrial router (ordered 1) [3]
- SIMcard [note 12].
- 2 x external 4G / 5G phone antennas (included)
- 2 x WiFi antennas (included)
- 4 x RJ45 router/switch ports (included)
- various magnetic mounting arrangements, such as vehicle roof or magnetic brackets for window or floor attachments.
- portable supply (building from parts)
- 12 volt 3S-2P Lithium pack (building from surplus spare batteries salvaged from laptops and the POC)
- 6 x Panasonic MH12210 3100 mAH cells.
- 30-14 volt input switch-mode down-converted to 12 volt via a d.c. to d.c. converter (ordered a 10A wide-input to 12 volt output for robustness - hope it is not noisy r.f. wise!)
- DrRobot 5V 25W dc-dc supply DR0205 [4] (ordered) [5] [6]
- Anderson 50A plugs
- 1 Anderson through-bulkhead connector for the box
- 12 volt 3S-2P Lithium pack (building from surplus spare batteries salvaged from laptops and the POC)
 |
 [note 13]
|
- various lengths of suitable gauge wire and cables
- USB mini-power cable for a pi 3B or USB-C for a pi 4
- various switches, fuse and circuit breaker
- CAT-6E jumper cables (will be made to required length if existing Reolink camera jumper cables are too long)
BMS
- 12 volt Lithium BMS https://www.ebay.com.au/itm/406049975669
- 12 volt Lithium BMS BMS-complex
Anderson Plugs
Grey 50A Anderson plugs are quite large but ubiquitous and a defacto industry standard. I am proposing to have the Anderson plug as an input power connector - which means the portable unit will work in vehicles like 4WD and be compatible with camping equipment.
- https://www.youtube.com/watch?v=yT3hFxNtEWk
- https://www.aliexpress.com/p/order/index.html?spm=a2g0o.tm1000015626.headerAcount.2.6f89130cya5s1o
other orders
wish list
- https://www.amazon.com.au/YQQZQ-Connectors-Compatible-Dustproof-Waterproof/dp/B0DFM9PYY7/ref=asc_df_B0DFM9PYY7?mcid=227bc0f2f4953252965f25e937b40934&tag=googleshopdsk-22&linkCode=df0&hvadid=712306754149&hvpos=&hvnetw=g&hvrand=11251374304418512398&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9071973&hvtargid=pla-2373765889820&psc=1&gad_source=1
- https://www.jaycar.com.au/panel-mount-with-two-50a-battery-connectors/p/PT4479
- https://www.amazon.com.au/dp/B0FYM85PNX/ref=sspa_dk_detail_1?psc=1&pd_rd_i=B0FYM85PNX&pd_rd_w=DiVwH&content-id=amzn1.sym.1466049c-a1d9-4b3d-b57f-ad4194b25db8&pf_rd_p=1466049c-a1d9-4b3d-b57f-ad4194b25db8&pf_rd_r=R4QE2676Y8AMMWYQXVMK&pd_rd_wg=M7pjX&pd_rd_r=0d4e59d6-26be-4441-8963-4ec06d3177ed&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw
- No good due to set frequency filters - dual channel SDR https://www.amazon.com.au/Nooelec-Flycatcher-Performance-Dual-Channel-Monitoring/dp/B0D18LC9FY
software
- aircraft tracking software
- piaware 10.2+
- dump1090-fa
- fr24feed
- net-utils
- web-servers
- nginx
- lighttpd
- htop
- gpsd for chrony and mobile tracking [11]
installation
See:
for installation details.
notes
- ↑ I feel the need for a portable raspberry pi so I can:
- experiment at the top of Mt Taylor and receive ADS-B tracks
- run with it in my aeroplane and obtain Internet Access while in the air
- run with it in the car, or when camping, and
- obtain internet access at home when the iiNet gateway is out
- ↑ Some safety and switching details:
- the input line for the main power should use a klixon circuit breaker
- the input power to the LTE should be switched
- the input power to the DRF0250 should be switched by bridging across switch on the board in order to control the power for the pi. You might want to just run the LTE router as a hotspot without the pi operating.
- the output wiring from the lithium batteries should be fused
- ↑ Pi Zero is not recommended for piaware use
- ↑ Various searches on the web with AI responses, and one forum where the pi4 uses 1.5W feeding Flightaaware SDR https://discussions.flightaware.com/t/power-consumption/84502
- ↑ The LTE router is running openWRT - wouldn't it be funny if it supported ssh and contained a raspberry pi?
- ↑ NEC2D can be used to simulate antennas - but resurrecting and compiling NEC2 FORTRAN will be a project in its own right. I also had C++ code archived off to drive NEC2 and do genetic antenna optimisation.
- ↑ This is in the ntp.server which is running chrony and gpsd. Paware was loaded so the pi had something else to do and could build entropy.
- ↑ The ntp.server and ntp2.server deployments are running 32 bit Debian.
- ↑ The YSWG deployment is running 64 bit Debian.
- ↑ Note that I have had prior success with the ublox modules - choose modules that have an SMA socket for an external active patch antenna, because it is more than likely you will need that antenna placed in a window area.
- ↑ You can use a raspberry pi 4 if you have more intensive workloads - noting the increased power consumption.
- ↑ I will enquire about connecting a new SIM card to my existing account rather than pay-as-you go top-up cards which are a pain to renew (Need to write another letter on company letter head to purchase and attach a new SIM card to the plan)
- ↑ Dual Anderson connectors can be wired together to permit daisy chaining. Do so through the circuit breaker unless one is put into the vehicle wiring. The later is the required arrangement for aircraft wiring.
- ↑ Wiring Preferences.
- ↑ Trixie libraries are not qualified by piware, though source code has been compile and binaries distributed by abxc567
references
- ↑ u-blox NEO-8 https://content.u-blox.com/sites/default/files/NEO-M8-FW3_DataSheet_UBX-15031086.pdf
- ↑ u-blox Neo-6 https://content.u-blox.com/sites/default/files/products/documents/NEO-6_DataSheet_%28GPS.G6-HW-09005%29.pdf
- ↑ Industrial LTE router https://www.ebay.com.au/itm/357913468700
- ↑ DRF0205 specifications https://wiki.dfrobot.com/Power_Module__SKU_DFR0205_
- ↑ DFR0205 https://au.mouser.com/ProductDetail/DFRobot/DFR0205?qs=lqAf%2FiVYw9iV86DO20EDuA%3D%3D&mgh=1&vip=1&srsltid=AfmBOoqULAhgrIOjyqIFshOyxoYlPQDBrAIY4gL9oe-sQtsqWcLg8V98lHM
- ↑ DRF0205 https://littlebirdelectronics.com.au/products/dc-dc-power-module-25w?srsltid=AfmBOord8Cbx8-lFHpBN-z8SNHul3T8A8qlGD9y714NdbRpivCy3pnpH
- ↑ abcd567 trixie binary apt repository https://discussions.flightaware.com/t/piaware-ver-10-0-on-trixie-aarch64-rpi-model-4/97562
- ↑ Raspberry pi OS downloads https://www.raspberrypi.com/software/operating-systems/
- ↑ flightaware repos wget https://www.flightaware.com/adsb/piaware/files/packages/pool/piaware/f/flightaware-apt-repository/flightaware-apt-repository_1.2_all.deb sudo dpkg -i flightaware-apt-repository_1.2_all.deb
- ↑ https://github.com/orgs/flightaware/repositories
- ↑ gpsd installation https://gpsd.gitlab.io/gpsd/installation.html