Is there an alternative for GPS?
Finding a wanted location without GPS?

If there aren't any, could someone direct me to a site which explains how to interface GPS with a PIC.

 

I don't think there is an alternative yet which is known to the general public. I have heard rumors that the military is working on a next generation system.

You interface to a GPS device with a UART, with or without an RS-232 transceiver. The data comes to you as a collection of ASCII strings. You need to write a program to parse the strings and extract the data you are looking for. In some cases the baudrate is quite high, like 38400 or 57600 and an offboard UART like the MAX3100 with it's 8 byte receive FIFO is a real advantage. Take it from me, the single buffered on board UART of the PIC, AVR, Z8, or 8051 families will have significant difficulty drinking from the fire hose, not to mention the RAM required for buffering.

 

The UK magazine did a series of articles on connecting PIC's to GPS modules, it's pretty easy to do.

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If you are wanting to find a location globally, then GPS is the only solution as far as I know.
In some parts of the world, it is possible to locate fairly accurately using mobile phone transmitters.
If you just want to find a position in a room for a robot for example, then maybe you could use some transmitters, eg infra-red or ultrasonic positioned around the room. I once saw a virtual-reality demo that used something like that.

If you want to use GPS. Get a cheap module that sends out NMEA protocol data strings using rs232 (TTL logic levels if possible) 4800 Baud and parse the strings with a pic microcontroller.
A useful guide to NMEA can be found at:
http://vancouver-webpages.com/peter/

I think the hardest part would be writing the program that does the maths to compare your present location with your destination and guide you to it.

 

That's why I mentioned EPE you can download the software from their website.

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Yes ...it is. It's cold INS (Inertial Navigation System). It uses a set of accelmeters for all 3 axes. Even in the 70' was quite acurate and was used for guiding planes. Was mostly replaced by GPS but modern variants (few Y old) are more accurate then civilian GPS.
Also the Rusians have a alternative but it's incomplete. U can buy 3D accelmeters or scavange. Some of them use rs232 potocol. The main problem is keeping the sys working all the time and giving from time to time accurate coordinates for reducing erors.

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If is too complicated.....most of the times is the wrong way.

 

There's the LORAN system, used in the USA, and apparently Russia and Japan

http://en.wikipedia.org/wiki/LORAN

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Says that couldn't find the server!

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now is OK. How about LORAN's precision? It's similar to that of civilian GPS?
Quite interesting.

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LORAN is only useable over inland waterways. It uses comparitively low frequencies and I'm not aware that anybody can use it reliably on land. The LORAN transmitters are placed along costal waterways with the signals being directed over the water.

LORAN receivers are priced for wealthy yachtsmen. If you have to ask the price then you obviously can't afford one.

 

Heath or someone like that used to sell what amounted to an AM broadcast receiver with an S meter and a rotatable ferrite loop antenna. One would tune to local or regional stations of known location then plot that on a chart. It would seem that this approach could be tied to a PC as a crude alternative. I am not suggesting that this is particularly good - but it might be something you could cook up as a school project.

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Actually Loran C does work over land and the carrier frequency is 100Khz. There are Loran C transmitter sites in places like Wyoming, Nevada, Indiana etc. Yes the receivers are bigger than GPS. But several years ago when there was a problem with GPS the Loran-C was still there. The U.S. Coast Guard operates the stations in the US.

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I think this is getting rather away from the original post?, where he has never actually really told us what he wants?.

But assuming he does want something like GPS?, none of the other suggestions are anywhere near as simple and easy to use!.

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True. What I was looking for was a replacement for a project I am doing. (I think I start a topic of this in Robotics).

My project is like a robot waiter (best analogy I can think of). It will be able to go to some fixed positions to deliver when prompted.

GPS is looking to be the clearest option. However, I was having doubts because if I want the robot to go to location C for example, I need to know the coordinates of location C first (I think). This would make the robot/application to be unflexible. If the location of C is to be moved, then I need to know the new coordinates for the robot to be able to get there.

Is there a better way of doing this? An alternative approach to have the robot to be able to moved to a location when needed. There will be several locations obviously.

Thanks.

 

So presumably you're wanting a VERY accurate location system, GPS probably isn't accurate enough for that.

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