How to use TS/PP - Draft with latest Garmin GPS

[Mallikarjuna]

Hello Folks,

I am trying to get a self training on TS/PP software that I recently installed in my desktop PC. It is a pretty good software to do travel time and delay analysis. I have a Garmin Nuvi 660 GPS with connects to PC through a regular USB cable. GPS unit has a mini USB plug point. It doesn't come with any cable which connects to PC through serial port.

TS/PP software recognizes GPS only when it is connected through serial port ( S232) cable. In the help, they have mentioned it the newer USB-based receivers will not work with TS/PP-Draft at present. Do you guys know is there any way I connect my GPS?

Thank you
-Mallikarjuna K

[bullock]

Hi, Mallikarjuna.

At present, you have at least two options:

• Use Franson's GpsGate (http://franson.com/gpsgate). It allows TS/PP-Draft (or any GPS-enabled applications that accepts NMEA input over a serial port) to work with Garmin USB-based GPS receivers (using the Garmin USB protocol) by emulating a virtual serial port. It looks like it costs about US$10/computer. Several TS/PP-Draft users have confirmed that it works fine with the software in NMEA mode. Unfortunately, last I heard, it does not emulate the serial port with the Garmin (proprietary) protocol. This means you can connect the GPS to the laptop out in the field and run just fine, but you cannot, as far as we know, take the GPS solo out in the field, use it to record intersection coordinates ("waypoints") and trip logs ("tracks"), then download to the computer when you return to the office.
• Use GPSBabel (http://www.gpsbabel.org). This will allow you to download pre-recorded trip logs from the Garmin GPS receiver and save them to a file that TS/PP-Draft ver. 8.0 can read. You'll probably want to save them as .GPX files, then import them TS/PP-Draft that way; although, there are other file format options that both GPSBabel and TS/PP-Draft share (e.g., .KML, .csv, and perhaps others). If you're using ver. 7.0, then .csv or perhaps .tsv are probably the best options. Whichever file type you use, please be aware that TS/PP-Draft has to calculate the speed and heading information, because the Garmin GPS receivers don't record that when you're recording track logs with the GPS solo (i.e., when not connected to a computer and using TS/PP-Draft to do the recording). This wouldn't be so bad, but for several reasons beyond TS/PP-Draft's control, the speed calculation gives a rather coarse estimate -- it may be off by, say, 3 mph or more. I may post a plot at some point illustrating this. Anyway, if you make a speed vs. distance plot, you'll see a blocky, stair-step effect in the speeds. The loss of resolution may be acceptable to you, but you should be aware of this penalty. Another penalty is that the automatic filter for cleaning trip logs is less effective because the lack of a GPS-measured speed renders useless some of the rules it can use for detecting bad points. This may not be so bad, though, because many of us prefer to do manual filtering by opening the Trip Log Details table along with the Network View, the arterial timings diagram, and the speed-distance plot, and identifying and disabling the points that look bad.

Regards.
Greg

[bullock]

Update: The FAQ section in the user's manual, the help file, and the web site include a topic http://www.tru-traffic.com/faq.htm#USBOnlyGarmin on using a USB-only Garmin GPS receiver to discuss these options in more detail.