-------------------------- AutoGPS V2.1 User's Guide -------------------------- Mike Rudin, March 1997 Introduction ~~~~~~~~~~~~ AutoGPS is a Psion 3a/3c add-on for AutoRoute Express (UK) or Automap Road Atlas (USA) which gives you a moving map, when you connect up a Global Positioning System receiver. It is intended for use within the British Ordnance Survey National Grid area, and in North America. Please note - this is not a program for the PC, and does not interwork with any PC software. You need the following: o a Psion Series 3a or 3c (512K or bigger) o Microsoft AutoRoute Express, version 1.00, or Microsoft Automap Road Atlas, version 1.00 o a GPS receiver with NMEA 0183(1.5 or higher) output, including the $GPRMC sentence o a Psion RS232 serial interface lead (as supplied with PsiWin). Note: the 3a and 3c need different leads. o a lead to connect the GPS receiver to the serial lead I have not tried AutoGPS on a Series 3c, but users report that it works. The backlit version of the 3c should be useful in a car at night. AutoGPS is not suitable for the Siena. If you're thinking of buying a GPS receiver, bear in mind that some of the cheaper ones don't have a serial data output, nor an external antenna input. I use a Garmin GPS 45, and recommend the newer 45XL. However, note that most of the Garmin models stop generating position information at speeds above 90 kt. If you have internet access, try Usenet newsgroup sci.geo.satellite-nav, and Peter Bennett's Web site: ftp://sundae.triumf.ca/pub/peter/index.html AutoRoute Express (TM) and Automap (R) Road Atlas are commercial software supplied on SSD. AutoRoute contains a fairly detailed road map of Britain and Ireland, and Automap contains a less detailed map of North America. Both calculate road routes between named places. AutoGPS observes the behaviour of AutoRoute/Automap by looking at its working memory, and controls it by sending messages to it that simulate key presses. Because specific memory locations are polled, this version of AutoGPS will not work any version of AutoRoute Express or Autmap Road Atlas other than v1.00. Installation ~~~~~~~~~~~~ Create a directory \APP\AUTOGPS on any disk, and copy either AGHELPUK.RZC or AGHELPUS.RZC into it. Copy AGPSUK.OPA or AGPSUS.OPA to any directory (e.g. \APP) on any disk, and install it on the System screen. If you like, you can un-install (remove) AutoRoute, as AutoGPS will start it automatically from either SSD slot or from the internal disk. AutoGPS will keep a record of settings in a small file, \OPD\AUTOGPS.ODB, which it creates on the internal disk. If you travel between the USA and UK frequently, you can have both sets of files on the Psion, but you'll need to "remove" one version from the System screen and "install" the other when you change country. Connect up the GPS receiver (see Appendix A) and get it to acquire its satellites. Adjust the receiver to output NMEA 0183 data (preferably 2.0 for higher position resolution), using the WGS 84 map datum (or optionally the OSGB 36 map datum for the UK version). Start up AutoRoute Express or Automap Road Atlas temporarily, and ensure that "Calculate dialog at startup" is set to "No" (in the Psion-Q dialog). This is to avoid a crash when AutoGPS starts up AutoRoute/Automap; see "Known Problems". Use in a car ~~~~~~~~~~~~ It is dangerous and probably illegal to use the Psion 3a/3c while driving; you need to keep your eyes on the road. Please only use AutoGPS as a passenger or when stopped. You may well get adequate GPS reception with the receiver's internal antenna just inside the windscreen (but not touching it), but you'll probably need an external antenna if you have a heated windscreen. See Appendix A for notes on powering from the car battery. Starting AutoGPS ~~~~~~~~~~~~~~~~ If AutoRoute/Automap is already running, AutoGPS will connect to it on startup. Otherwise, AutoGPS will normally attempt to start AutoRoute/Automap (looking for it on both SSDs). In the second case, the two applications are tied together; if you exit AutoRoute/Automap, AutoGPS will exit, and vice versa. Switching between AutoGPS and AutoRoute/Automap ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If AutoGPS has started AutoRoute/Automap, then you can switch to AutoGPS in one keystroke using Shift+System. Alternatively you can assign a button to AutoGPS (Psion-A in the System screen) to make it easy to switch to. From AutoGPS, you can switch to AutoRoute/Automap using Esc or Psion-A (or just "A"). AutoRoute/Automap will be started if it isn't already running. Each time AutoGPS switches to AutoRoute/Automap (including at startup), it will force the map window to become active, so gaining control of the cursor position, as part of the process of keeping track of what AutoRoute/Automap is doing (see "Known Problems"). Jumping to a location ~~~~~~~~~~~~~~~~~~~~~ Switch to the AutoGPS screen, then use Psion-J (or just J) to move the AutoRoute/Automap cursor to a specific location. For the UK version, type in a grid reference, which must be two letters plus an even number of digits, with or without spaces. An Ordnance Survey road atlas is useful here, as it is clearly marked with grid references, and has a place index with grid references. Also, A-to-Z street atlases often have Eastings/Northings marked on their grid lines. For the USA version, type in a latitude and longitude. Several forms of input are acceptable, e.g. for latitude: Input Interpreted as 34 34.0000 degrees North -56.21S 56.2100 degrees North +32 23.2 32 deg., 23.20 minutes North Longitude is measured positive East, so all longitudes in the USA are negative. However, in the Psion-J dialog, longitudes are by default interpreted as negative for convenience. GPS position fixes ~~~~~~~~~~~~~~~~~~ When enabled (Psion-G), AutoGPS will attempt to receive NMEA data from the GPS receiver. Typical reasons for this failing are: o Remote Link is already on; see Psion-L on the System screen. On a 3c, select "none" or "IR" to make the serial lead available to AutoGPS. o The serial lead is not plugged in. o You plugged in the serial lead while powered-up; try switching the Series 3a/3c off and back on. o The serial lead is not correctly connected to the GPS. o The GPS receiver is not sending NMEA 0183 data. o The NMEA data does not contain the $GPRMC sentence. o There is no position fix (poor satellite coverage). The Series 3a serial lead is powered-up while getting a fix, but it only takes about 10-20% more power than when AutoGPS is doing other things. If you want to maximise battery life and can put up with infrequent updates, set a pause between getting GPS fixes (Psion-F dialog). GPS Moving Map ~~~~~~~~~~~~~~ Each time a GPS fix is obtained, AutoRoute/Automap's cursor will normally be forced to show the position. AutoGPS can only do this while AutoRoute/Automap is 'under control', i.e. when its map window is active and there is no menu etc. displayed. In AutoRoute/Automap, you can use all the controls as normal. If you manually move the cursor away from the GPS position, AutoGPS will detect this, and temporarily suspend its cursor-control activity. It will resume 20 seconds after you stop moving the cursor, or the next time you switch from AutoGPS to AutoRoute/Automap, whichever is the earlier. A "GPS" message is shown in the top left corner while the cursor position is being controlled. You can configure this (see Psion-D dialog) to show position, speed, mileometer/odometer, and track direction (figures and/or arrow); the arrow gives a coarse indication of your track (north, south, east or west), and is updated while you are moving faster than the limit set in the Psion-F dialog. Once you've been stationary for more than two minutes, no track direction is shown. As the AutoRoute/Automap cursor nears the edge of the screen, AutoGPS re-centres it; you can select the limit in "Screen around cursor" in the Psion-D dialog. One option is "Depends on track" - if you select this, AutoGPS will average your track direction over the past few minutes, and attempt to keep more map visible ahead of you, at the expense of more frequent re-draws. Accuracy ~~~~~~~~ Your reported position will often appear off-road. The two main sources of error are: 1. AutoRoute/Automap's approximations in road positions; this can be up to a couple of km in the UK, or worse in the USA, especially outside big towns. In Automap, the grid resolution is 240 metres. 2. SA (Selective Availability) errors in the GPS signal deliberately introduced by the US military. At the time of writing, this causes your apparent position to wander randomly, with 100m root mean square "noise", meaning that occasionally you may be a couple of hundred metres off. Lobbying of the US government may result in this corruption being turned off permanently. 3. In the USA, AutoGPS's translation of lat/long to map position may be inaccurate. I'd particularly welcome feedback about such inaccuracies, as I'm not in a position to try it out for real. If you detect a systematic offset in your area, it would be helpful if you can quote exact lat/long (together with map datum used), and say where the cursor appears in relation to the true point on the map, i.e. how many miles off to the southeast or whatever. For best accuracy, you must ensure that the GPS's NMEA positional output is adjusted to the WGS 84 or (UK only) OSGB 36 map datum, and (UK only again) use the Psion-F dialog to make AutoGPS match the one selected. The UK version of AutoGPS converts lat/long positions to grid-reference form slightly faster with OSGB NMEA data, as there are fewer adjustments to make. On the Garmin GPS 38/40/45/90, for example, use the "Navigation Setup" page to set the Map Datum to "WGS 84" or "Ord Srvy GB". In the UK, if you use WGS 84, and also set "Position Format" to "British Grid", you may notice discrepancies of up to a few hundred metres between the Garmin display and AutoGPS; most of this is due to map datum differences. Apart from this, AutoGPS's idea of a position should agree with the GPS receiver to within about 15 metres over most of Britain. Mileometer/odometer ~~~~~~~~~~~~~~~~~~~ To calculate how far you've travelled since the last GPS fix, the mileometer/odometer multiplies the current speed reported by the GPS receiver by the time since the last successful fix, so the accuracy is improved by making the fixes as frequent as possible (pause time zero). If you turn off the Series 3a/3c, then turn it on some time later, the mileometer/odometer will update to a very inaccurate value, as it will assume you've been travelling at your current speed while powered off. After you start up AutoGPS or turn on GPS fixes, the first subsequent GPS fix is not counted in the calculation. When stationary, the mileometer/odometer will slowly clock up distance due to a 'wandering' GPS position, especially when Selective Availability errors are on. Track ~~~~~ The displayed track direction is true (not magnetic, nor grid), and only gets updated when your speed is above that set in the Psion-F dialog. If you move slower than this, or stop getting GPS fixes, the track display will vanish after two minutes. Copyright, feedback etc. ~~~~~~~~~~~~~~~~~~~~~~~~ AutoGPS is Copyright (c) 1996-1997 by Mike Rudin, its author. You use it on the condition that the author is not held responsible for any loss or damage, however caused. AutoGPS may be freely distributed, provided that only minimal charge is made for distribution, and provided that it remains unaltered and is always accompanied by this file. There is no charge for using it, but please feel free to send tokens of appreciation, as well as bug reports, comments etc. to: Mike Rudin 26 Lovell Rd Cambridge England CB4 2QR Or email me at: mrudin@cix.co.uk Known Problems ~~~~~~~~~~~~~~ While AutoGPS is active (e.g. no menu displayed), the Series 3a/3c's auto-power-off is inactive. This may be fixed in a future release. If AutoGPS crashes (e.g. due to lack of system memory), it may leave a copy of AutoRoute/Automap running, without it appearing on the System screen. You should be able to find it by stepping through the running applications using Shift+System, or by re- starting AutoGPS. If you stop getting cursor movements and top-left-corner messages in AutoRoute/Automap (this seems to happen after calculating a route or switching the scale bar on/off), switching to AutoGPS and back should restore operation. Try zooming in one level if zoomed right out. AutoGPS should only try to display messages and control the cursor in AutoRoute/Automap when the map window is active. However, in AutoRoute/Automap if you press Menu and Help in that order, AutoGPS will mistakenly send control messages. The running AutoRoute/Automap process is expected to have a name like "ROUTE.$12". This is unlikely to concern you, but if you've somehow renamed the process, or you have another application that starts up with that name, then there could be problems. I've not found a way to force a continuous display of grid reference on the AutoRoute/Automap screen; it needs updating every couple of seconds. You get the best effect with zero pause between GPS fixes, and a GPS receiver that sends $GPRMC sentences frequently. If AutoRoute/Automap is set to display the "Calculate route" dialog at startup, then AutoGPS will probably cause it to crash with Exit number 158. Appendix A - Connecting Up ~~~~~~~~~~~~~~~~~~~~~~~~~~~ The most tricky part of getting AutoGPS to work is probably connecting the GPS receiver. Some of the following advice on how to do it is due to Steve Litchfield, who has been through it all for the moving-map feature in his excellent shareware application "Mapper 3a". If you have a 3-Link serial lead for a Psion 3a, the most compact arrangement is to have a cable directly from the GPS receiver to a 9-pin mini-DIN plug which plugs into the 3-Link "podule". However you may already have a lead from your receiver, and it might be easier to connect the serial lead's PC or Mac cable to that. In any case, only the following two wires need be connected (see your 3-Link manual page 66): GPS 9 pin mini-DIN Ground ---- Pin 5, SG (signal ground) Serial output ---- Pin 2, RD (received data) View of socket 9 8 7 6 5 4 3 2 1 If you have the newer serial lead for the Psion 3c, which does not need the podule part, then the above does not apply, and you should connect the GPS receiver to the female DB-9 connector. Steve Litchfield says that in the UK, Tony Denson or Peter Kitsen at Positioning Ltd on 01403 271114 can help, as they have the expertise and stock to put together all the elements you might want, from cables to cradles. Also Maritec, on 0141 5542492, do cables from most GPS systems to the 3-Link podule. If you use AutoGPS in a car, I recommend you run the GPS receiver and Series 3a/3c off a good-quality power regulator to save batteries (while AutoGPS is running the Series 3a/3c draws about twice as much current as when idle), but you need to be careful to avoid damaging both devices. Don't use the car battery voltage directly on the Series 3a/3c, because the voltage is too high. The Garmin GPS 45 will run directly from a car battery, but it is risky to do so because a car's electrical system can sometimes surge to very high voltages that can cause damage. The almost identical GPS 40, and the new GPS 38, definitely need an external regulator. The negative side of the power input to the Series 3a/3c is connected through the 3a/3c to the serial lead interface ground, so if your GPS receiver also needs a positive supply relative to its interface ground (the Garmin GPS 45 does), then it's OK to power both machines from the same supply. The Series 3a/3c needs a 9 Volt supply, and you may be able to run the GPS receiver off the same supply; check the manuals for voltage details and possible warranty problems if you use unapproved power regulators. The whole lot may look like this: Optional _ external | | 9 Volt regulator antenna _| |_ plugged into cigar _____ | | lighter socket |_____| | | | |_____| | | | ___|___ | | | | | | | | | | +9 Volt Power to GPS and 3a/3c | O O O | | |____________________________ | O O O | | | | _____ | | | || ||___| _________ ___________ | || ||______/ \___| |_| || || ** \_________/ | | ||_____|| Psion 3-Link |___________| |_______| *** Psion Series 3a/3c GPS Receiver ** This bit might be two leads plugged together. *** This bit is not present on the 3c serial lead. [End of AUTOGPS.TXT]