GPS information shipped with Psi-Mapper/London 1.7 --------------------------------------------------------------------------- What's rather caught my imagination here has been the possibility of hooking the Psion up to a GPS (Global Positioning System) unit, which are now available for a few hundred pounds (though don't buy the cheaper models) and which are smaller than the Psion. In case you're not sure what a GPS is, it's a small unit with a built-in aerial which receives positioning information from the american GPS satellite system (see picture) to tell you your current latitude, longitude, velocity, altitude etc. By hooking the two together the possibility exists to use the Psion as a very flashy real-time moving-map display. Of course, if all this seems like whimsical gadgetry to you, you're probably right, but then I like gadgets! My Garmin GPS45 cost about œ255 including VAT in October 1995 from a London dealer. Note that ETA etc are calculated using your set average speed in your personal preferrences. I've tried using actual speed from the GPS etc, but so far the results are just as transient and and/or approximate as using a set average ... watch this space ... So what do you need if you want to try all this out? * Psion 3a or 3c with 150k of free system memory (100k needed by the program, and 50k margin for other programs you might start and stop during the running of Psi-Mapper) * Installation of Psi-Mapper/London v1.7.04 or higher * PsiWin cable OR 3-Link cable (the part with the 'podule' on) * GPS receiver with NMEA 0183 v1.5 or higher interface (one of the Garmin units is ideal) and data cable to the 3-Link connector or podule. Also worth thinking about is integrating power leads for your Psion and GPS into the wiring if you intend to run them both for long periods! Note that the Psion doesn't *have* to be on all the time, you can just turn on when you need a 'fix'! Acquiring the above I'll assume you already have a Psion and 3-Link, or you probably wouldn't have got this far! First item on your shopping list is to buy a GPS. The next bit's the tricky one. The easy way to connect all this together is to contact Tony Denson or Peter Kitsen at Positioning Ltd on 01403 271114, as they have the expertise and stock to put together all the elements you might want, from cables to cradles. Or try Maritec on 0141 5542492, who do cables from most GPS systems to the Psion 3-Link podule. 3a owners: The more 'Do-It-Yourself' approach is to make up, or get made, a cable to go from the GPS to the Psion podule yourself. As most GPSes have different connectors, you'll need the specific data cable for your unit from the manufacturers, which is normally about 20 pounds. You'll then need a 9-pin mini-DIN connector soldering on the end with the bare wires. 3c owners: Simply use a null-modem adapter between the GPS data cable and the PC end of the PsiWin cable. If you're not sure what this means, take both cables to your local computer shop and show them both leads!! Getting the GPS link working Assuming you now have all the bits you need: 1. Plug everything in 2. Start up the GPS and position in your car to get good satellite reception. I find it works very well wedged on top of the dashboard, but if you have a heated windscreen this may be a problem for you, as the mesh of wires can block the signal. 3. Start up Psi-Mapper/London and go to the map you want the moving map icon displayed on-top of, and set your required sticky displays/options. If you're wanting to try out the ETA/Distance left option, choose your settings in the 'Moving Map Settings' dialog, and 'select' a destination (place or overlay item) by 'find'ing it in the usual way. When all is ready, select 'GPS Moving Map' from the right-hand menu. 4. If all is well, you'll see one of two icons on your map. Either a cross-hair showing current position or a 'Poor GPS' icon. The latter will appear whenever your GPS's output quality deteriorates to warn you that it doesn't really know where it is anymore. Try waiting or re-positioning your GPS .... 5. If the cross-hairs get too close to the edge of the screen, the map will re-centre itself and stay in 'GPS Moving map' mode. Have fun! Extra notes * If you haven't got a GPS yet, there is a little simulator routine built into the program to show you what you'd see * If you should blow anything up or injure yourself in any way, please note that I take no responsibilty whatsoever for use of this software product! And if you're driving, keep your eyes on the road! I mean it! ONLY USE THIS PROGRAM ON THE MOVE WHEN SOMEONE ELSE IS DRIVING. IF YOU *DO* USE THIS ALONE ON THE MOVE, I WILL NOT BE HELD RESPONSIBLE WHEN YOU CRASH HEAD-ON INTO A JUGGERNAUT!!! * Technical one, this. Your GPS map datum should be set to WGS 84, if it's not already! Also, the NMEA version supported by Psi-Mapper is 0183 version 1.5. Psi-Mapper gets its information from the NMEA sentence $GPRMC, so if your GPS doesn't output this word you're stuck! Get in touch and I'll see what I can do ... See also my guide on troubleshooting GPS operations at the end of this file. Recommendations for purchasing a GPS Don't buy the cheapest models! They may not have the right NMEA computer interface! Shop around before deciding which model to buy or how much to pay! Start looking at the Garmin units (30,45,55,65,75,90 etc), which have a very good reputation. Places to try in your quest: * Positioning Ltd on 01403 271114 * Pumpkin Marine on 0171 4806630 * Garmin UK on 01794 519944 --------------------------------------------------------------------------- Troubleshooting GPS operations --------------------------------------------------------------------------- So, you've been trying out Psi-Mapper on your Psion with your new GPS gadget. And it doesn't seem to work, either at all or terribly reliably ... Well, you're in the minority, because there are lots of people out there using it all quite happily together, but I accept that what with all the things that could go wrong, a few brief notes might be in order! --------------------------------------------------------------------------- Things to think about and look out for: * Are you using the latest version of Psi-Mapper? If not, download it from here. * Is your GPS 100% compatible with NMEA 0183 v1.5 and above? Psi-Mapper needs the $GPRMC word output every 2 seconds or more frequent. The best way to check what your GPS is outputting is to install the 'Comms' app on your Psion (you'll find it on the 'C' drive), set the parameters to 4800 baud, 8 bits, no parity, no handshaking, and see what appears on your screen. You may find it useful to capture some of this output to a text file for later analysis, or for sending in for diagnostic purposes. Garmin GPSes seem to meet these criteria very easily, other makes tend to be more non-standard. In particular, the Magellan GPSes only output sub-sets of the NMEA standard data sets. If you've got a Magellan, make sure you're using v3.9 of greater of Mapper-3a/GB or v1.7 or greater of Psi-Mapper/London, as I've been tweaking the code to work more reliably on the Magellan's cut-down NMEA signals. * How are you linking the two together? Are you 100% sure the pins/wires in your connections aren't shorting or dropping out? Are all the cables pressed fully home? Using the pin-outs given in the GPS and PsiWin/3-Link manuals, try 'buzzing out' the cables you're using to ensure that the signals are going where you think they are! * Make sure your GPS's output is in the right NMEA mode. For example, the Garmin defaults to using its own proprietary GARMIN/GARMIN mode. If you've addressed the above and are still having problems, please email me! Steve Litchfield