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HermannSW
Posts: 1607
Joined: Fri Jul 22, 2016 9:09 pm
Location: Eberbach, Germany
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WoodenBoardPi

Fri Oct 11, 2019 8:42 am

Until now my "Raspberry laptop" consisted of several distinct parts:
https://www.raspberrypi.org/forums/view ... 5&t=219214

Yesterday I mounted everything besides small wireless keyboard onto a 4mm thick wooden board
(backside of board I used to test wireless payload drop mechanism):
- 7inch DPI LCD (https://www.waveshare.com/wiki/7inch_DPI_LCD)
- RGB 50P TO 40/50P adapter
- Pi3B

The adapter and Pi3B with diagonal screws with nuts, the LCD with two small dots of superglue on top left and right backside.

Two USB ports are used, one for wireless keyboard dongle, the other for Scorpi B+ gooseneck camera mount (with 70mm lens v1 camera):
https://www.raspberrypi.org/forums/view ... 8#p1493151

This is WoodenBoardPi in its home position when not moved around. The right part of board is reserved for mobile powering with 3S 1000mAh 25C lipo. Will be filled when I have resolved the undervoltage symbol issue, perhaps caused by LM2596 adjustable step-down module I try to use. This will be a good weather only outside laptop since eveything is unprotected. I already tested that WoodenBoardPi perfectly fits onto a 1.5m high music stand's plastic music rest for indoor/outdoor operation. I use 1m long camera flex cable to be able to put gooseneck camera mount into a 2nd unpowered Pi2B apart from WoodenBoardPi:
Image


This is a screenshot (taken with raspi2png via ssh session) showing what the 70mm lens on v1 camera does show in raspistill preview. It is rainy outside, I am quite impressed that even horizon tree tops can be seen. Even more since the image was taken through black window-frame fly-screen (2mm wide hexagonal meshes of 0.1mm filament):

Code: Select all

33.3m  next house gable top (bottom right, roughly 5m higher than camera)
62.2m  low energy street lighting top (bottom left, even higher)
>500m  horizon tree tops
Image


This is gmaps-pedometer.com measurement between location of WoodenBoardPi in our house and street lighting top:
Image


P.S:
I found a workaround for outdoor powering with our car:
A cigarette lighter to 5V/2.1A adapter, then one or more USB extension cables, and finally converter cable to Pi micro USB.
⇨https://stamm-wilbrandt.de/en/Raspberry_camera.html

https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/github_repo_i420toh264
https://github.com/Hermann-SW/fork-raspiraw
https://twitter.com/HermannSW

User avatar
HermannSW
Posts: 1607
Joined: Fri Jul 22, 2016 9:09 pm
Location: Eberbach, Germany
Contact: Website Twitter YouTube

Re: WoodenBoardPi

Fri Oct 11, 2019 4:26 pm

I switched to the other side of the house, into (also 1st floor) bathroom, this time with music stand.
WoodenBoardPi sits easily on plastic music rest, the Wireless keyboard has a safe place there as well.
Image


The target I had was to verify clear line of sight to house of my friend Jan, 1.73km distant, on the other side of river Neckar. Clear line of sight might be advantageous for some kind of wireless communication. We want to avoid laser light, instead maybe try whether proprietary ESP32 Wifii low rate feature that is capable of doing 1km will allow for 1.73km as well. If not, with directional antenna ESP32 can even do 10km distane well, but transmit power needs to be kept an eye upon to avoid violating regulations.
Image


My friend's house is in center of 2MP (v1 camera mode1) photo.
As can be seen clear line of sight is given to the rooms in his house's 1st floor, not disturbed by trees.
Surrounding of friend's house is a bit pale, but hey -- it is 1.73km distant:
Image


This is screenshot showing the view I had while calibrating the 70mm lens with camera on gooseneck mount:
Image
⇨https://stamm-wilbrandt.de/en/Raspberry_camera.html

https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/github_repo_i420toh264
https://github.com/Hermann-SW/fork-raspiraw
https://twitter.com/HermannSW

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B.Goode
Posts: 8903
Joined: Mon Sep 01, 2014 4:03 pm
Location: UK

Re: WoodenBoardPi

Fri Oct 11, 2019 4:41 pm

Thank you for sharing your 'journey' and design adventure.

I don't remember the exact details because it is some years since I had to implement links like this, but maybe simple 'line of sight' although necessary may not be sufficient for a reliable service. There is something called the Fresnel Zone which has to be interference free, and that is broader in all directions perpendicular to the point-to-point line, being at a maximum at the mid-point.

Apologies if you have already taken this into account, or if it does not impact your choice of technology.

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HermannSW
Posts: 1607
Joined: Fri Jul 22, 2016 9:09 pm
Location: Eberbach, Germany
Contact: Website Twitter YouTube

Re: WoodenBoardPi

Sat Oct 12, 2019 12:09 am

Thanks for that information, I did not know about Fresnel zone:
https://en.wikipedia.org/wiki/Fresnel_zone

All I did in the past was experimentally determine maximal length where Wifi connection works.
In basement of IBM Böblingen lab I found that even 170m inhouse in line of sight with quality 30/70 are no problem.
That surprises me now wrt Fresnel zone, since the basement floor width and height are less than 3m:
https://www.raspberrypi.org/forums/view ... 0#p1204793
⇨https://stamm-wilbrandt.de/en/Raspberry_camera.html

https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/github_repo_i420toh264
https://github.com/Hermann-SW/fork-raspiraw
https://twitter.com/HermannSW

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