Z Technology, Inc.
Procedure using Z Technology Software with Survey System
By: John Purdy
Z Technology, Inc.
Z Technology Survey System software is made up of several programs. Each program is easy to learn and simple use. The output from one program is input to the next program. The final output is either a colored dot plot on a blue background screen, or colored dots on a DeLorme Street Atlas Map. The color of the dots indicates RF Field Strength. In the course of doing a survey, the survey team uses three programs. Survey.exe, Sign_flt.exe, and GP_Plot.exe. Each of these programs operate under DOS, this gives better real time performance than operating under Windows. Sign_flt.exe and GP_Plot.exe may also be run under windows. The survey team generally consists of a driver who simply drives, and a navigator who in addition to navigating who starts and stops the system at timely intervals and checks the integrity of the collected data.
Survey.exe is the data collection program. It is the primary program used while doing drive tests. It's output is a comma delimited text file.
Sign_flt.exe is a filter program that removes records from the data file that contain erroneous GPS locations. Remember that due to the governments addition of Selective Availability that GPS readings are accurate to within 100 meters 99% of the time. Those other 1% sometimes need to be removed from the data set.
GP_Plot.exe is a plotting program that plots the collected data on a blue background screen. Most drivers, navigators, and data analysts can recognize locations on the dot plot by recognizing the pattern of the trail of dots on the screen as roads that were driven.
Optionally available is the DeLorme Street Atlas package which includes a Z Technology translator ToDeLorme.exe to translate the Z Technology format comma delimited text files to DeLorme input data files. The translator creates a DeLorme input file for each frequency surveyed during the drive test. Once imported into DeLorme Street Atlas, the colored dot trail previously viewed on a blue background is now overlaid on a street map. The DeLorme mapping is generally done at the conclusion of a drive test, after all the data has been collected, and is ready for final analysis.
Starting a Survey
Install the Z Technology DSS-5006GPS or DSS-5007GPS system in a vehicle. GPS and RF receive antenna should be on roof of vehicle, the systems cigarette lighter plug gets power from the vehicles cigarette lighter. Follow the quick start instructions that come with the system.
Start by doing a short drive test to familiarize with the unit. Say 5 minutes of driving. Start the Survey.exe program, drive for 5 minutes then stop the Survey.exe program. Now look at the data you've recorded by running the GP_PLOT.exe program. You'll see a trail of colored dots that are in a pattern of the streets you drove. North is at the top.
Now that you know how to run the program and plot the data, do a longer drive, say an hour. Start the Survey.exe program, drive for an hour then stop the Survey.exe program. Again look at the data you've recorded. Run the GP_Plot.exe program. Each time you run the Survey.exe program give the data file a new name. Short names like PDX1 for say "Portland drive test, first session" are useful because later you'll be combining the results of all the sessions into one big file.
If when looking at a sessions data with GP_PLOT the data is all bunched up in just a couple of corners of the screen, you've probably captured one of those 1% GPS locations that is not just off, but way off. The Sign_flt.exe program can be run on this sessions data to remove the suspect record(s). Run the GP_PLOT.exe program again and you'll see the familiar dot trail of your drive path.
Completing the Drive Test
Drive as many sessions as you feel necessary to cover the area you are interested in. Each session may be as long as you feel comfortable with. When all the sessions are complete, you will have multiple data files that need to be combined all into one file so all the data can be viewed together.
Say you have 5 data files PDX1.txt, PDX2.txt, PDX3.txt, PDX4.txt, and PDX5.txt to combine all the files into one, use the DOS copy command.
Copy PDX1.txt + PDX2.txt + PDX3.txt + PDX4.txt + PDX5.txt PDXall.txt
Run the GP_PLOT program on the PDXall.txt file and you'll see the blue screen plot of your entire drive. You can Zoom and Pan using the Page Up, Page Down, and Arrow keys on the keyboard.
Unlike the data collection session that must be run under DOS, all analysis can be done under Windows. With the data from each drive session combined into one data file the GP_PLOT program can be used to analyze the data. Signal strength thresholds can be set so you can modify the color transitions to mean something specific to you. Screen captures of the plotted data can be pasted into documents like Word and Powerpoint for presentation.
People who are unfamiliar with the drive test process sometimes have a hard time understanding the data when presented on blue screen dot plots. The optional ToDelorme translator allows the same information to be plotted on street maps which can improve a presentations clarity.