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Thread: Low cost GPS Module

  1. #1
    MikeHibbett Guest

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    Hi,

    I have produced a number of GPS designs for use in car, and it has been suggested that one of them could be of use for geocaching.

    The device is home build, and appears in this months Everyday Practical Electronics magazine ( http://www.epemag.wimborne.co.uk/ )

    I run a support site for the project here

    www.drivesentinel.co.uk

    It was suggested that I could modify the design to display OS coordinates ( it currently shows Lat/Long) for geocaching. This is the first time I have heard about geocaching, and it looks like fun. If there is interest in a low cost handheld unit especially tailored for geocaching, I would be interested in hearing what features would be useful. If there is sufficient interest I will publish a design that can be freely constructed. Besides being handheld and displaying the OS coordinates, what else would be useful?

    Feel free to email me or leave messages here.

    Mike.

  2. #2
    MikeHibbett Guest

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    Already thought of a feature that might be of interest. What if the unit recorded your location over 10s, so that you can later download the data and view the route you took on an online map, like this:

    http://www.drivesentinel.co.uk/map.html

    (Well, with a route marker rather than balloons) I'm already working on a gps logger for another application using this technique.

    Building your own gps locator is not as complicated or expensive as it sounds, plus there is the opertunity to add geocaching specific features.

    Mike.

  3. #3
    The Hokesters Guest

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    Hi Mike,

    Not sure how much you know about Geocaching (shout if I am teaching grandma all about her eggs) but essentially Geocachers mostly use a hand held device that basically has a "follow the arrow" function (see below).


    Some also use mapping GPS receivers (cheats) :lol: :lol: :lol:

    Now I had a quick think and what would be useful to folks who do not have products like TomTom would be proximity alerts for their car.

    I have pointed this thread out to the Geocaching.com UK forums so you will probably get a few more replies soon.

    Simon

  4. #4
    lordelph Guest

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    Well I'd want to build a caching hat - the antenna would be on top of the hat, with a sort of heads-up-display monocle for pointing the way!

  5. #5
    The Hokesters Guest

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    Oh and I just thought of a couple of other things you should need to know.

    1. We use co-ords on the WGS84 system in degrees, minutes and seconds.
    2. To make it useful the ability to load the co-ords in via a PC would be invaluable.

    Premium members of Geocaching.com can download batches of co-ordinates and upload them into programs such as www.gsak.net and into their GPS receivers. Your device would be ideal for geocaching if you could also upload the co-ords in this way.

    I don't know the ins and outs of the data files but someone much smarter than I will be along shortly to add to my ramblings.

    Great idea this is - thanks for bringing it up here.

    Simon

  6. #6
    The Hokesters Guest

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    Originally posted by lordelph@Nov 3 2005, 08:32 PM
    Well I'd want to build a caching hat - the antenna would be on top of the hat, with a sort of heads-up-display monocle for pointing the way!
    Sorry about Pumpkin Man above Mike. You may think he is being sarcastic but actually he is being perfectly serious

  7. #7
    lordelph Guest

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    Oh now you're talking - vegetable based caching accessories!

  8. #8
    lordelph Guest

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    On a serious note, I think it's hard to beat a cheap Geko 201 unit for caching (£80 now?) so there's no point replicating the features in such a unit. It would have to be something novel that might enable new ways to play.

    How about building one which can pick signals from "cache beacons" - you'd make a weak radio transmitter which transmitted its coordinates every 30 seconds, and have a GPS unit which could both tell you where you are and where the beacon is. The beacon could be on a person tryign to evade capture, or at an actual cache.

  9. #9
    MikeHibbett Guest

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    Originally posted by The Hokesters@Nov 3 2005, 07:40 PM

    >Sorry about Pumpkin Man above Mike. You may think he is being sarcastic but actually he is being perfectly serious

    lol. No problem, I undestand. Seen stranger things myself. Was once a radio ham )

    The coordinate system is no problem, I have been looking at the algorithm to do it for another project. Ideally though I am looking for the *software* features that are missing in commercial products that could be implemented in a hobby solution.

    I'm no wizz with mechanics, so others would have to build the hat!

    Keep the ideas coming though...

    Mike.

  10. #10
    lordelph Guest

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    I guess for software you want to be able to some of the things people use PDAs for. You want a display capable of displaying say 40x10 chars minimum so you could read cache descriptions and hints straight out of a GPX file downloaded onto the unit.

  11. #11
    MikeHibbett Guest

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    Originally posted by lordelph@Nov 3 2005, 07:49 PM
    How about building one which can pick signals from "cache beacons" - you'd make a weak radio transmitter which transmitted its coordinates every 30 seconds, and have a GPS unit which could both tell you where you are and where the beacon is.
    Thats do-able. I have suitable tx/rx modules in front of me now, from RF solutions. The range wouldn't be great though (probably less than 1KM line of sight). But I can put together a design for something with a GPS receiver, LCD, route logger and 'beacon receiver' that would cost about 80 pounds in parts. Your idea reminds me of the 'fox hunting' direction finding games I used to join in when I was an active radio ham, and before children!

    Mike.

  12. #12
    MikeHibbett Guest

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    Originally posted by lordelph@Nov 3 2005, 08:01 PM
    I guess for software you want to be able to some of the things people use PDAs for. You want a display capable of displaying say 40x10 chars minimum so you could read cache descriptions and hints straight out of a GPX file downloaded onto the unit.
    Those sized displays are expensive, I'd probably go with what I have on the CameraWatch2 unit - a 16x2 line LCD. Scrolling text is quite readable.

    Mike.

  13. #13
    lordelph Guest

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    A unit for caching use will almost certainly need to be able to render a reasonable direction arrow, so a basic 16x2 text display might not cut it.

  14. #14
    MikeHibbett Guest

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    Originally posted by lordelph@Nov 3 2005, 08:14 PM
    A unit for caching use will almost certainly need to be able to render a reasonable direction arrow, so a basic 16x2 text display might not cut it.
    On my other units I just display heading in degrees...
    What about just text?
    "Left a bit"
    "straight ahead"
    "Behind you"

    It would be a little like a text adventure game

    Today was the first that I heard of this, yet I noticed on the USA website there are over a 100,000 posts on the forums. Must be quite popular. I like the idea of combining walking with technology...

    Mike.

  15. #15

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    Originally posted by The Hokesters@Nov 3 2005, 07:36 PM
    1. We use co-ords on the WGS84 system in degrees, minutes and seconds.
    Sorry to carp but don't most of us use Degrees, Minutes and Decimals of a Minute (DD MM.mmm) ?

    I think to produce a device to satisfy us all would probably weigh about 20 pounds!
    Enjoy your caching!

  16. #16
    MikeHibbett Guest

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    It's ok, the software for that bit wont weigh much!

  17. #17
    lordelph Guest

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    It's certainly popular - someone will be along shortly to spout some statistics I'm sure. Go to the gc.com search page and bang your postcode in, you might be surprised!

    As for a textual "hint" as to where the cache is, that would be, er, novel!

    As well as "straight on" and "left a bit" it could throw in useful advice like "have you looked under those twigs" and "it's got to be in that ditch" etc

  18. #18
    MikeHibbett Guest

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    Originally posted by lordelph@Nov 3 2005, 08:34 PM
    As well as "straight on" and "left a bit" it could throw in useful advice like "have you looked under those twigs" and "it's got to be in that ditch" etc
    lol.

    Maybe I will, just for the laugh. I have over 2Mbyte storage space to play with so I'd have to fill it with something!

    How about

    "Shush. I think I can hear it"

  19. #19
    Kitty Hawk Guest

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    Yeah, I agree with John, I'd like a device weighing 20lbs.

  20. #20
    The Hokesters Guest

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    Originally posted by John Stead+Nov 3 2005, 09:27 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (John Stead @ Nov 3 2005, 09:27 PM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-The Hokesters@Nov 3 2005, 07:36 PM
    1. We use co-ords on the WGS84 system in degrees, minutes and seconds.
    Sorry to carp but don&#39;t most of us use Degrees, Minutes and Decimals of a Minute (DD MM.mmm) ? [/b][/quote]
    Told you I was dim&#33;

    Wot &#39;e sed is wot I meant&#33; :lol:

  21. #21
    birders Guest

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    <<Was once a radio ham >>

    Once? ONCE?? You never stop being a Radio Ham - it&#39;s incurable, just like geocaching&#33;

  22. #22
    MikeHibbett Guest

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    Originally posted by birders@Nov 4 2005, 10:16 AM
    <<Was once a radio ham >>

    Once? ONCE?? You never stop being a Radio Ham - it&#39;s incurable, just like geocaching&#33;
    lol. You loose many things when children come along, including hobbies, spare time, hair, and money&#33;

    Mike ( G6COQ )

  23. #23
    skysurfer Guest

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    Originally posted by The Hokesters@Nov 3 2005, 07:36 PM
    1. We use co-ords on the WGS84 system in degrees, minutes and seconds.

    Simon
    Yup, that&#39;s what got me confused for a while, too. Yes we use the WGS84, but in hddd°mm.mm (from http://www.geocaching.com)
    When we use OS, we need to use Ord Srvy GB & British Grid (E-Trex). Kept walking into trees...

    Unless I&#39;m barking?


  24. #24
    The Hokesters Guest

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    Mike,

    Can I suggest you bring this exact same subject up on the Geocaching.com forum (United Kingdom)?

    I think it will generate much more interest there.

    Simon

  25. #25
    MikeHibbett Guest

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    Thanks Simon will do.

    I&#39;m just going to see if there is a cache near me in Kent. Might introduce the family to the sport this weekend...

    Mike.

  26. #26
    MikeHibbett Guest

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    Just been thinking thinking about the issue of direction indication, and how a character based LCD may not be sufficient.

    One solution would be to augment the LCd with an led &#39;circle&#39;, with say 8 LED&#39;s to display N, NE, E SE etc. Would that be acceptable?

    I notice that there are encrypted hints on the pages with the cache locations. These could be downloaded at the same time as the GPS coordinates, and decrypted while in the field.

    I&#39;m working on the circuit design at the moment. The parts cost look to be between £65 and £80 for a unit with rechargable batteries, 2x16 character LCD, LED &#39;compass&#39; display, GPS receiver, 2MB memory, 5 keys and a PC interface. For anyone who may be interested.

    Mike.

    p.s. Thanks for the link to the cache site locator, I see there is a cache less than a mile from me at blue bell hill. Will take a walk over there at the weekend with the kids.

  27. #27
    lordelph Guest

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    Sounds like fun for anyone who wants to try to put their own unit together, but people won&#39;t be beating a path to your door to own one&#33; I&#39;d certainly be interested in the software side, always wanted to have a crack at embedded software.

    Here&#39;s a few more suggestions in varying degrees of seriousness
    • Nice bright LED torch
    • Self-inking cache stamp built into the case
    • Built in pencil

    I&#39;d be interested to know what it would cost to build one with a decent b/w LCD display. My little Geko unit probably has the smallest usable size of 64x100 pixels.

  28. #28
    MikeHibbett Guest

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    >but people won&#39;t be beating a path to your door to own one&#33;

    Wouldn&#39;t make any difference if they did, because I am not looking to sell anything. I&#39;m looking for sensible ideas for features to add to a free, open design.

    Mike.

  29. #29
    John &amp; Hazel Guest

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    Mike.
    I don&#39;t know if you are aware of this thread over in the GC.com Forums
    Open GPS

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