Use of GPS on Mil-Sim Games

[Vigil]

Is there any kind of monthly GPS service fee?

Swatt Six-Four,

There is no monthy service fee. GPS is free to the whole world.
It is even free for the new version of GPS which is generally accurate up to a 10 ft radius of where you are. You can get better accuracy than 10 ft, but it's generally around there.

There rino system with it's team location system seem's extremely promising.
I have never used it and I'm pretty interested also.

From what Pivot said, it seems really easy to use.
GPS is generally easy to use though. Turn it on, it takes time to find out where you are (about 1 min for me).

You rarely need to press anything if you don't need to mark down locations or routes (GPS's can track the route you took, like a path or how you got to where you are).

I hope that helps you for now until someone can give you a review of a Rino. I don't have one...both my GPS's are very old.
One thing to note, if you get an outdoor dedicated GPS, it won't work well in cities where there are building's in the way. However, my GPS set up for city driving with street directions and everything, works great in both enviornments. But it doesn't come with an outdoor map, you will need to get that separately. It seems to be able to hold signal better in wooded areas as those are similar to buildings, but accuracy goes crazy (maybe up to a 50 ft radius) and sometimes I totally lose reception. Then you have to wait to get signal and all that all over again.
Outdoor maps differ in that they show topological charts, and has items like streams, rivers, etc... City maps show stores, streets, housing, addresses, landmarks, etc...

They suck on batteries. Real bad.

Also, unless you hack them, you have to transmit a location request to get a location back, it's not updated in realtime.

[Jixton]

Originally Posted by Haggis

Has anyone found GPS to be of use during Mil-Sim games, for squad coordinating and location finding etc...i have a GPS and have used it once in a game, obviouslyeveryone in the team needs one to relate to coo-ords. would like to hear comments. thanks

I use it some time on big field that I don't know very well. But i've found it to be easyer to coordinate troops with a map and coordinate like : b5, c7,etc....

You got to configure the coordinate protocol so every ones GPS is on the same map system.

Personaly I've always prefer map and compass when i'm out there....But thats me.

I'm suggesting that if all your team have GPS and you all trained togeter with it, it will work great.

My 2 bbs.

[Phil_Black]

A good system is the garmin Rhino.

Why ? Because it's communicating your position to the others gps unit (must be Rhino) within transmission range (5 miles).

That is making it very easy to coordinate !

[Drake]

Entirely different setup I've used, generally just to keep my ass unlost when I go hiking/photo taking in the woods, but it could be used for MilSim if you were playing on a big enough chunk of real estate:

I use a Pocket PC with a bluetooth GPS receiver, and a piece of software called GPS Tuner. (actual setup is an iPAQ HX2410 running WinMobile2003 and HOLUX GPSlim 236 receiver, with GPSTuner 5.0)

Why this setup? GPS Tuner is designed for offroad navigation, unlike most other software (TomTom, iNAV, etc) which are designed for road navigation. More importantly it allows you to import and calibrate maps of your choosing, including from Google Earth. You can also scan a [paper] topo map and use that, or even a hand drawn map if you can put coordinates to locations on it.

Actually the feature list probably offers a better glimpse of its capabilities:

http://www.gpstuner.com/overview.htm


One interesting-looking feature I haven't gotten to use yet is position sharing with another user (so you can see where they are on your map, and vice versa). This could be interesting for coordinating two fire teams, I suppose.

The HOLUX 236 receiver is small (about the size of a Zippo) and doesn't use much power (I've used it for 10 consecutive hours, and it was still running).

If I power manage my pocket pc properly I can get about 10 hours of runtime with the bluetooth radio going.

[Vigil]

Great idea to use a Pocket PC instead.

I would believe they offer more fuctions and faster access to those functions with your touch screen.

One question though, how fast does a pocket pc secure you position and how well does it work under foliage cover?

I know they work in the city so I would assume that they are pretty capable of acquiring and holding satellite signal, but if you could confirm that, I will definitely consider switching to a pocket pc setup.

[Kimbo]

I have a holux unit that I use with my Audiovox 6700 phone works great, but I prefer my Garmin Rhino 120 cuz I don't have to fart with checking a map against where my team mates are. If you are playing as a team get rhinos, it's the easiest way to keep track of team mates.

[Drake]

Originally Posted by Vigil

Great idea to use a Pocket PC instead.

I would believe they offer more fuctions and faster access to those functions with your touch screen.

One question though, how fast does a pocket pc secure you position and how well does it work under foliage cover?

I know they work in the city so I would assume that they are pretty capable of acquiring and holding satellite signal, but if you could confirm that, I will definitely consider switching to a pocket pc setup.

The HP iPAQs are built really ruggedly; they're bulkier and a bit heavier than other PPCs/PALMs but with their rubberized finished and very solid construction they feel like a man's hand held.

The touch screen is very handy (a lot of nav software have oversized buttons so you can press them with your fingers instead of having to use the stylus; very useful when driving, for example) and the flip up visor keeps your screen safe.

As for it getting a fix on my position, since it's a bluetooth GPS receiver, everything happens on the HOLUX 236's end, which works completely independently from the Pocket PC (which can even be switched off).

That being said, it's important to know there are several types of information being transmitted by GPS satellites, which can affect TTFF (Time To First Fix); in addition to the regular GPS signal broadcast used to calculate positions, a GPS receivers needs other data, specifically an almanac and ephimeris. These contain information about where in the sky satellites will be in relation to a geographic position at a given time, and specific information about each satellites orbit (the almanac contains very imprecise locations whereas the ephemeris contains very precise orbital data and clock corrections).

Almanac data remains valid for several months, however ephemeris data degrades after 3 hours (it's generally only considered valid for 4-5 hours).

So when powering up, before a GPS receiver can acquire it's first fix, it must check that its data tables are up to date, and update them if they aren't. This affects the type of startup the receiver will do, and each startup takes a different amount of time:

A "factory startup" occurs on new receivers, or receivers that have been reset, had their firmware upgraded, etc. and also on receivers that haven't been used for an extended period of time (several months). Almanac and ephemeris tables are blank and all data must be downloaded. GPS satellites transmit at about 50 bps (bits per second -- 50 bps works out to 0.006 KB/s, REALLY slow even for a 1 KB textfile). A complete almanac takes 12.5 minutes to download in optimal conditions. Ephemeris data must also be downloaded from each satellite "in view." It's generally accepted that under real world conditions, this type of startup will take about 20 minutes.

A "cold start" is what will usually be experienced if the unit hasn't been used for some time, but the almanac is still valid. In this case, a full set of ephemeris data must be downloaded. This generally takes 30 seconds to a minute under normal conditions.

If the receiver was used recently, only a "warm start" is required, which involves minor updates of the ephemeris. This will take less than 30 seconds. An up-to-date receiver (used within the past several hours) can perform a "hot start"; in the case of the 236, it can get a position fix almost instantly.

As far as foliage cover, it depends on your receiver. The 236 uses SiRF Star III architecture, which is now common in most new GPS devices; they're able to operate with very weak/degraded signals, and can compute a 2D position with as few as 2 satellite signals.

Also, keep in mind that while accuracy can be as good as "within 3 meters", when factoring in all errors, accuracy for GPS is only accurate to within 15 meters (i.e., even if you do get 3 meter accuracy, you always have to expect it can potentially vary as much as 15 meters).

Given how slowly you'd progress on foot, over terrain with heavy tree cover, and the inherent inaccuracy of GPS, it's not a big problem. From experience, even if you have "coverage gaps", between last known positions and the on-screen map, you can still figure out where you are (unless you were out on the water or in the desert, for example, where there are no immediate references).

Another thing you want to do, for this type of application, is use SIRF programming software to disable "Static Navigation" (if its enabled on your unit), since having it on will muck up slow-speed navigation (such as hiking).

[QcWarzone]

We're in the process of gearing the team up [Felix Tactik]. We have evaluated equipment and have elected the RINOs from GARMIN. We have ordered Topo map packs and are testing them this week-end in an internal game in a field. Will let you guys know how it goes. As for the position system, as soon as you either communicate or hit a certain button, your location is sent to all your teammates who have you on their list. We also very much appreciated the FRS/GMRS possibilities. Once you buy a US version, you will need a cable but hte updates for the canadian GMRS system is free [unlike the US] Yeah, for once we get something for free and no hassle!!!

Stay tuned!