A navigation technology that does not rely on satellites. - Page 1
Forum section: electronics / general

author: hamster_nz
author_rank: Super Contributor
timestamp: April 28, 2019, 04:38:39 am
content: Location services without space vehicles and online tracking...https://www.aweigh.ioA Raspberry Pi plus add-ons and python scripts that uses the position of the sun to tell you where you are.I can't tell if they are trying to be serious, or it is an 'art piece' .Poe's law is a b#%ch.

author: hamster_nz
author_rank: Super Contributor
timestamp: April 28, 2019, 04:43:56 am
content: I watched the video, and now I deeply regret ever mentioning this!

author: hagster
author_rank: Frequent Contributor
timestamp: April 28, 2019, 06:52:08 am
content: TLDR;it could "work" if you only need position to the nearest country.The "basics" page is worth a look.https://www.aweigh.io/basicsI haven't looked in detail, but the premise sounds reasonable. Basically they are using the polarisation of scattered sunlight to try and determine the position of the sun. Then if you also know the time, you can calculate your location. This is basically what a sextant does.I note that nowhere do they show the result. My guess would be that if they could make this work to within 5 to 10 degrees(lat or lon) they would be doing really well. There will be plenty of error in the polarisation measurement. An error of 1 degree would could equate to a error of 100km on the ground. And the angular diameter of the sun is about 0.5degrees to start with.Lets not get started on the list of things that they say rely on sat positioning. Many actually use it to derive time. This project just uses a regular clock.

author: Domagoj T
author_rank: Frequent Contributor
timestamp: April 28, 2019, 08:57:41 am
content: It would also need an accurate compass and some very accurate maps of magnetic declination.How would it be affected by various cloud formations? What about night time? What about reflected light that is depolarized? I don't see it nearly accurate enough to be usable.

author: techman-001
author_rank: Frequent Contributor
timestamp: April 28, 2019, 11:15:52 am
content: Quote from: hamster_nz on April 28, 2019, 04:43:56 amWhy ? this is a well known science in avian tracking:"Unlike GPS devices, which are too large and heavy for the warblers, geolocators use miniaturized sensors to detect and record solar light-level data hundreds of times each day. These data are stored on a tiny computer chip and can be downloaded only if the birds are recaptured. Daily locations can then be inferred from calculations based on day length and the timing of solar noon and midnight."https://vtecostudies.org/blog/the-blackpoll-warblers-daring-ocean-migration/I have been a (small) part of such a project and results were impressive, but not GPS impressive.

author: hamster_nz
author_rank: Super Contributor
timestamp: April 28, 2019, 11:09:00 pm
content: Quote from: techman-001 on April 28, 2019, 11:15:52 amI can see that as working - maybe within a degree or two, and you can run a 'best fit' and smooth things out.However, for Aweigh, there a python script (you can see athttps://github.com/build-aweigh/build-aweigh/blob/master/Software/RaspberryPi/Latitude_Longitude.py)And it is buggy - the servo driving the polarising filter starts out OK withCode:p = GPIO.PWM(18, 50) #Frequency is 50Hzp.start(5) #Duty cycle is 5 to turn 60 degreesCode:while time.time() < t_end:# Take two sensor readings#First reading.... code to take reading ...# Turn motor 60 degreesp.ChangeDutyCycle(7.5)time.sleep(1)# Second reading... code to take reading ...... calculation ...At no time do they reset the filter back to the original orientation for subsequent passes.But the web site and video is pretty slick.All they need is "micro-blowers" and they are ready for a Kickstarter

author: 0culus
author_rank: Super Contributor
timestamp: April 29, 2019, 04:42:09 am
content: Bring back LORAN-C

author: techman-001
author_rank: Frequent Contributor
timestamp: April 29, 2019, 05:41:02 am
content: Light level Geo-location is a well known alternative to GPS as mentioned in followups, here is a video showing Kirtland’s warbler migration tracks by Nathan Cooper of the Smithsonian Migratory Bird Center.These use tiny geolocator tags with a battery life of years due to low power mcu usage, no GPS and the RTC being the only fully powered perepheral.

author: borjam
author_rank: Unknown
timestamp: April 29, 2019, 01:18:55 pm
content: Indeed, those techniques are commonly used to track migrating birds.How could you put a tracking device on a barn swallow otherwise?

author: JacobPilsen
author_rank: Regular Contributor
timestamp: April 29, 2019, 05:24:47 pm
content: There is an older Czechoslovak television series "Visitors - Expedition Adam 84", where the central supercomputer blindly relies on positioning anything derived fromhisown position, but (after decades of service) stands outside the spirit level...youtu.be/b-wwgN-KbpI?t=1350

author: iMo
author_rank: Super Contributor
timestamp: April 30, 2019, 06:16:59 pm
content: Light Level Geolocator:https://hackaday.io/project/28550-light-level-geolocator

author: rrinker
author_rank: Super Contributor
timestamp: April 30, 2019, 09:02:08 pm
content: Quote from: borjam on April 29, 2019, 01:18:55 pmWell two of them could carry it between them on a line....

author: hamster_nz
author_rank: Super Contributor
timestamp: April 30, 2019, 09:24:46 pm
content: Quote from: imo on April 30, 2019, 06:16:59 pmNice project - but confirms that the resolution is to about a degree (which is cool for some uses, but not for finding your way to your secret spy meet-up)Quote

author: Canis Dirus Leidy
author_rank: Regular Contributor
timestamp: May 01, 2019, 11:17:15 am
content: Quote from: hamster_nz on April 28, 2019, 04:38:39 amMore looks likean unholy mix of ДАК-ДБ-5 and БЦ-63a computerized toy versions ofreal life devices for celestial navigation, heavily filled with advertising.