APRStrfc APRS TRAFFIC SPEED MONITORING AND REPORTING 24 May 2004 ------------------------------------------------------------------------- WB4APR TRAFFIC.HST FILE: To tell APRStfc where the local traffic choke points are located, I used the standard APRS .HST file format. Here are sample entries for our area (Greater Baltimore/Washington-DC area). POINT DAYTIME LAT LONG DIR DL RNG STRT STOP --------- ------- -------- ------------- --- --- ---- ---- Bowie-W +123456z3857.00N\07644.00Wm270/010/1.0 0600 0900 Bowie-E +123456z3857.00N\07644.00Wm090/010/1.0 1500 1800 NwCrltn-W +123456z3856.70N\07648.00Wm270/010/1.0 0600 0900 NwCrltn-E +123456z3856.00N\07654.00Wm045/010/1.0 1500 1800 SevrnBR-W +123456z3901.00N\07629.00Wm270/010/1.0 0600 0900 SevrnBR-E +123456z3859.50N\07631.50Wm090/010/1.0 1500 1800 Here DIR is the direction of travel, DL is the delta angle acceptible to be considered on that route, RNG is the acceptible range from that point, and STRT and STOP are the start and stop times of voice reporting(the times are not currently used). This exact TEXT format is included so that the Sign-post shows up properly on the D7 screen but also additional information is included which shows the direction of the traffic lane at that point that is to be monitored and the range from that point that is of interest. APRStfc scans through this list on receipt of any new moving vehicle position report checking to see if the vehicle is within range of the choke point. Interestingly, when traffic slows down to say 30 MPH or less, then even a 2-minute tracker has a very good chance of being captured in that window (2 packets within a mile of the choke point)... MAKING YOUR TRAFFIC.HST FILE: The easy way to make a TRAFFIC.HST file is to use APRSdos to simply move your cursor around to the various choke points and hitting INPUT- ADD-OBJECT and entering the NAME of the SpeedPost. Then for the COURSE enter the direction and for the speed, enter the ANGLE LIMIT (typically 10 to 20 deg (plus/minus)). In the comment field, type the 3 digit RANGE limit (usually 1.0 miles). You may also enter the START and STOP times (thought at this point, they are ignored). Then FILE-SAVE hitting "T" to force a TRAFFIC.HST file. Similarly, you can edit a TRAFFIC.HST file by using the FILE-NEW command to clear memory, and then using FILE-LOAD and also selecting "T". THen you can continue to INPUT-ADD new SPEED-POSTS or on the P-LIST, edit or delete entries. Since all of these choke-points do not actually show on the map unless they have current data, I added a new MAPS-OVERLAYS-TRAFFIC command which will overlay all of the choke points onto the map temporarily. These points show the location and a DIRECTION indicator to help you assess their applicability. DIFFERENCES TO normal APRSdos version 864: 1) removed Fade-DFing, NTS message formats, GPS and WX interface 2) Upped Capture size from 101 to 173 stations (5 pages) 3) Added MAPS-OVERLAY-TRAFFIC for viewing SPD-POSTS in TRAFFIC.HST file 4) Turned off Dead Reckoning of SPD-POSTS. (should do in all APRS) 5) Users should use JUST-MOBILES command frequently to see mobile situation 6) FILE-LOAD command (if FILE-NEW has cleared memory) can select "T" to allow loading the TRAFFIC.HST file. 7) FILE-SAVE command has the "T" option to save TRAFFIC.HST (Always keep a backup! because it is easy to overwrite...) 8) CONTROLS MENU (TAB) has CONTROLS-TRAFFIC to toggle on and off traffic SPD-POST generation. The status of CONTROLS-TRAFFIC is shown in the middle of the CONTROLS DISPLAY (hit TAB).