21

How would GPS trackers work when underground? Poorly I have no personal experience with Alltrails, but the GPS apps which I have used in the past mostly did not cope well with GPS reception being spotty. Generally this resulted in strange erroneous routes being tracked, with large jumps in between points where the device had a GPS signal. How bad this is for ...


17

Assisted GPS is different from inertial navigation. It uses ground stations to transmit GPS almanacs and ephemeris for faster GPS start-up. There are also wide-area augmentation services such as EGNOS which work in a manner similar to differential GPS to improve accuracy by transmitting positioning signals from ground stations. Needless to say, both of ...


7

GPS and similar technologies do not work at all underground, they can be blocked fairly effectively by dense tree-cover or being deep in a valley, even with clear views of the sky. Any thickness of rock will be impenetrable by the radio waves used to communicate with the GPS satellites. Inertial guidance technology is improving, particularly with the advent ...


6

The point of a navigation course is to teach people how to navigate, not how to use particular electronic devices. The principles of navigation are most easily taught using ordinary (paper) charts, without having to deal with the idiosyncrasies of particular devices - not to mention that it's easier to provide working charts for all the students if they are ...


4

(Un)Follow the water. Water will always flow down-hill. If you go in the opposite direction to the current, you will be travelling uphill. If you were randomly placed and have a map showing waterways, but not the contour lines (e.g. google maps street-map style presentation) you can get a generalized idea from the river direction(s). If you were traversing ...


4

As others have stated, the way to keep track of your position when you can't use GPS is inertial navigation, also known as dead reckoning. This uses various sensors, such as accelerometers, magnetometers and gyroscopes, which form an IMU (inertial measurement unit). The issue is that it is by definition subject to drift (so with time the estimated position ...


4

First of all, there are a couple of things maps do really well: They are big, so you can see the whole picture clearly But you can also fold them to see exactly what you need They can show you, with a high level of precision, multiple places at once Those are very important feature, for me. Much more than showing you that "you are here", or that ...


4

The simple answer is that electronics fail, paper doesn't. You can read the paper map now, 6 hours from now, next week, next month, next year and it will be the same, but your devices will run out of power and be unusable in a short time-frame. Those points in your question all rely on the use of powered devices. The GPS on your tablet/phone/watch all have ...


4

Depending on the country rules may change but generally you only need to know navigation rules (i.e. https://www.navcen.uscg.gov/?pageName=NavRulesAmalgamated) and possibly additional rules for your region (i.e. https://boat.wa.gov/boating/the-laws/). There is basically all you are required to know. If you have your own sail boat or use friends' boats - that'...


3

To expand a bit on Toby Speight's answer, I want to follow up on this comment of yours: I agree fully - any time spent dealing with the particular implementations is a distraction from that objective. Yet paper based navigation spends time teaching how to work a protractor, how to measure angles, how to move parallel lines, how to calculate distances with a ...


3

Probably the most important things are to use the data it's easiest for you to get, and to state clearly what system you are using. If your phone or GPS gives you decimal lat/long, give the rescue services that. If it gives you DMS or UTM, give them that. Rescue services will be better at converting than you, the stressed, injured and frightened victim. If ...


2

To supplement @fgysin answer: Modern smartphones contain enough sensors (acceleration, gyro, compass) to do inertial navigation. These sensors are not of a great precision, so I think the integration errors will accumulate quickly. Searching for "inertial navigation app" gives some results that pretend to do the thing. I am really curious and will ...


1

While you are unlikely to be able to identify the uphill trend of such a large area, water is the key to doing so if limited to natural features. It would be difficult to follow water to the absolute highest point in an entire region, but you will at least get to local high points. As you noted the general slope is very shallow. Local peaks will distort the ...


1

Garmin offers a "BirdsEye" product which is satellite image files that can be loaded directly onto a handheld GPS receiver. Use your BirdsEye Satellite Imagery subscription with BaseCamp™ to quickly transfer an unlimited amount of satellite images to your device, with frequent updates, and seamlessly integrate those images into your handheld’s ...


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