New GPS

[crudolph00]

Just picked up a new handheld GPS. It's a Delorme PN-40. I've played with it a little, but still have a lot to learn on the ins and outs of the unit. Does anybody have one and have any valuable info on tricks/tips with the thing and GPS use when STHF. Thanks.

 

[longbow]

I don't expect it to work when SHTF.....

 

[Dr Falken]

Maps, maps, maps. Get county maps in areas that you plan to operate. Topographic maps, etc. Learn how to read and navigate by them. Increase your area knowledge of areas around you.

 

[Iron22]

Get a good compass and learn to use it well

 

[E5RANGER375]

GPS are great for recreational activities, but if SHTF, throw it away.

1. all they have to do is flip a switch and it wont work.
2. they can track you.

 

[pathfinder317]

GPS are great for recreational activities, but if SHTF, throw it away.

1. all they have to do is flip a switch and it wont work.
2. they can track you.

and never bury your weapons and rely on a GPS to find them again for those very reasons.

 

[firstrock]

2. they can track you.

Not if you only have a GPS receiver!!

Dead reckoning and terrain orientation would serve you better in a SHTF scenario! Learn to use the terrain and natrual features to navigate and you should never get lost!!!

I wish I had a nickel for every time a 2nd LT got us lost in the Army while using a GPS!

 

[E5RANGER375]

Not if you only have a GPS receiver!!

Dead reckoning and terrain orientation would serve you better in a SHTF scenario! Learn to use the terrain and natrual features to navigate and you should never get lost!!!

I wish I had a nickel for every time a 2nd LT got us lost in the Army while using a GPS!

i agree that learning land nav is the best. but yes they can track you off a GPS reciever only. They know where that signal is going to off the sat.

 

[firstrock]

i agree that learning land nav is the best. but yes they can track you off a GPS reciever only. They know where that signal is going to off the sat.

A receiver does not send a signal to a satellite! A receiver receives the signal from the satellites and triangulates your pos based on the receivers dir/dist/elevation from the satellites. Now a two way GPS can be tracked by the satellites as well as most cell phone based GPS apps, OnStar etc. Knowing where the mortars are on the Earth is paramount to sending accurate rounds down range so I am very familiar with finding accurate positions on the earth using various sources and methods. As your username suggests that you were a Ranger, I'd expect you to be familiar with how a GPS works on a basic level.

 

[E5RANGER375]

A receiver does not send a signal to a satellite! A receiver receives the signal from the satellites and triangulates your pos based on the receivers dir/dist/elevation from the satellites. Now a two way GPS can be tracked by the satellites as well as most cell phone based GPS apps, OnStar etc. Knowing where the mortars are on the Earth is paramount to sending accurate rounds down range so I am very familiar with finding accurate positions on the earth using various sources and methods. As your username suggests that you were a Ranger, I'd expect you to be familiar with how a GPS works on a basic level.

thats basicly what i said but in a shorter much simpler term. I fully understand how it works, but if you think they cant pick you up off a GPS reciever then maybe you just dont realize their technology. even without a sat, every electronic device can be tracked. even the ones that recieve only, it makes no difference. they can use your kitchen microwave as a listening device and thats OLD technology.

they can track whats sucking signal. Similar to how they could tell how many people are watching a certain TV show, in a basic explanation.

 

[iamaclone45]

they can use your kitchen microwave as a listening device and thats OLD technology.

 

[firstrock]

they can track whats sucking signal. Similar to how they could tell how many people are watching a certain TV show, in a basic explanation.

OK. I fail to see how you came to this conclusion regarding the GPS receiver since it isn't "sucking" signals. As per Howstuffworks.com

" The GPS receiver figures both of these things out by analyzing high-frequency, low-power radio signals from the GPS satellites. Better units have multiple receivers, so they can pick up signals from several satellites simultaneously.
Radio waves are electromagnetic energy, which means they travel at the speed of light (about 186,000 miles per second, 300,000 km per second in a vacuum). The receiver can figure out how far the signal has traveled by timing how long it took the signal to arrive. In the next section, we'll see how the receiver and satellite work together to make this measurement.


GPS Calculations


On the previous page, we saw that a GPS receiver calculates the distance to GPS satellites by timing a signal's journey from satellite to receiver. As it turns out, this is a fairly elaborate process.
At a particular time (let's say midnight), the satellite begins transmitting a long, digital pattern called a pseudo-random code. The receiver begins running the same digital pattern also exactly at midnight. When the satellite's signal reaches the receiver, its transmission of the pattern will lag a bit behind the receiver's playing of the pattern.
The length of the delay is equal to the signal's travel time. The receiver multiplies this time by the speed of light to determine how far the signal traveled. Assuming the signal traveled in a straight line, this is the distance from receiver to satellite.
In order to make this measurement, the receiver and satellite both need clocks that can be synchronized down to the nanosecond. To make a satellite positioning system using only synchronized clocks, you would need to have atomic clocks not only on all the satellites, but also in the receiver itself. But atomic clocks cost somewhere between $50,000 and $100,000, which makes them a just a bit too expensive for everyday consumer use.
The Global Positioning System has a clever, effective solution to this problem. Every satellite contains an expensive atomic clock, but the receiver itself uses an ordinary quartz clock, which it constantly resets. In a nutshell, the receiver looks at incoming signals from four or more satellites and gauges its own inaccuracy. In other words, there is only one value for the "current time" that the receiver can use. The correct time value will cause all of the signals that the receiver is receiving to align at a single point in space. That time value is the time value held by the atomic clocks in all of the satellites. So the receiver sets its clock to that time value, and it then has the same time value that all the atomic clocks in all of the satellites have. The GPS receiver gets atomic clock accuracy "for free."
When you measure the distance to four located satellites, you can draw four spheres that all intersect at one point. Three spheres will intersect even if your numbers are way off, but four spheres will not intersect at one point if you've measured incorrectly. Since the receiver makes all its distance measurements using its own built-in clock, the distances will all be proportionally incorrect.
The receiver can easily calculate the necessary adjustment that will cause the four spheres to intersect at one point. Based on this, it resets its clock to be in sync with the satellite's atomic clock. The receiver does this constantly whenever it's on, which means it is nearly as accurate as the expensive atomic clocks in the satellites.
In order for the distance information to be of any use, the receiver also has to know where the satellites actually are. This isn't particularly difficult because the satellites travel in very high and predictable orbits. The GPS receiver simply stores an almanac that tells it where every satellite should be at any given time. Things like the pull of the moon and the sun do change the satellites' orbits very slightly, but the Department of Defense constantly monitors their exact positions and transmits any adjustments to all GPS receivers as part of the satellites' signals."

I still don't know how "they" could track a receiver that has no ability to transmit data. If I follow your theory correctly, then "they" can track me on my MP3 player just because I am "sucking" FM radio signals? I think not.

As for your comparison of TV ratings, ratings are COLLECTED via a set top box that is installed on your TV with the sole purpose of COLLECTING data and REPORTING that data usually via landline. There is no mysterious Govt agency spying on what you and i watch unless you have agreed to it first.

HowStuffWorks "How do TV ratings work and how do they figure out how many people are watching a show?"

I am done with this thread!

 

[Blackhawk2001]

GPS are great for recreational activities, but if SHTF, throw it away.

1. all they have to do is flip a switch and it wont work.
2. they can track you.

Who is "they" and how will they track you? If you're talking about DoD, they can fuzz the resolution for civilian GPS locations from 3m to 30m. Otherwise, if the system gets shut down, it will be outsiders that do it.

How does a passive receiver gps get tracked? It isn't transmitting anything, it's receiving satellite signals.

 

[WWIIIDefender]

If SHTF then GPS=Great Piece of S#!^

 

[Blackhawk2001]

Someone suggested I study up on GPS. I've been using GPS since 1996 for aviation and SAR and was using LORAN in 1980. I think I understand GPS and its capabilities pretty well.

One of the issues with GPS is its return-to-start capability. My first GPS in 1996 had a RTS of about 30m, which made it tough to find that dropped optic, or whatever. My next GPS (circa 2001) was a little better, but still not sufficient to find a dropped M-60D barrel in a stand of trees (dropped from a Huey, that is). It also didn't work well under said trees. My latest GPS (eTrex Legend C) is capable of 3m accuracy in the open with good reception.

Having said that, the only GPS of which I am aware which can be actively tracked is (perhaps) the Garmin Rhino series, which has the capability to transmit its location to another Rhino GPS.