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GPS Receiver Recommendations

I've had hands-on experience using Tru-Traffic with a few different types of GPS receivers, and they're not equal. The short advice is to get one that uses both of the following

• either the NMEA 0183 protocol or the Garmin (proprietary) protocol, and
• a serial interface, PS/2 interface, or a Bluetooth interface, or a "virtual" serial port. By "virtual" serial port, I'm referring to units that have a USB connection but include a software driver for serial port emulation.

Recording a Trip Log using the GPS Receiver solo vs. Tru-Traffic

Some GPS receivers double as GPS data loggers; they can record their own trip logs ("tracks"), which gives you options:

1. You can take the GPS receiver in the field solo, let it record the trip logs, then import the trip logs into Tru-Traffic when you return to the office. For Garmin GPS receivers connected with a serial cable, you can download directly into Tru-Traffic; otherwise, you can use software that comes with the GPS receiver or that's freely available to save the trip logs to a file for importing into Tru-Traffic. Advantages of this include
   • convenience (fewer cables and equipment to deal with),
   • expense (no need to buy another laptop or license to Tru-Traffic), and
   • you may already have a workable device, as you can use a smart phone.
2. You can connect the GPS receiver to a laptop running Tru-Traffic and operate it as a GPS "mouse", and let the software record the trip logs for you. With the basic GPS receivers that don't have a recording feature, this is your only option. Advantages of this include
   • higher accuracy in the speed on some GPS receivers (which can otherwise have from 2 to 5 mph of random noise in the speed)
   • the option to synchronize the signal controller clocks and satellite clocks, if you don't already know the signal cycle start time,
   • the option to view the moving "now" line on the arterial timings diagram to see where you are within the signal cycle,
   • the ability to confirm that the timings within Tru-Traffic agree with the timings in the signal controllers,
   • the ability to record trips of almost indefinite length (you don't have to worry about GPS memory or battery life, if the GPS and laptop are plugged into the vehicle's electrical system), and
   • typically high quality data as the device typically mounts magnetic on the roof of a vehicle with good view of the sky.

A smart phone, iPhone or Android, serves as an example of option #1, a GPS data logger to record trip logs. For recommendations and tips, see John Albeck & Charles Askar's Instructional Guide Mobile Travel Time Data into Tru-Traffic. And here are my own bonus tips:

• For long trip logs, you'll probably prefer to export to CSV rather than GPX, as Tru-Traffic can parse CSV faster, saving import time.
• On the Android, I recommend Ultra GPS Logger (cost $8.99) over Geo Tracker (free), as the former will save speed and heading in its CSV file, whereas it seems the latter will not. This matters especially if your TT&D reports include Fuel Consumption or Emissions, which can be highly sensitive to the accuracy of the instantaneous speed measurement. Also, with the Ultra GPS Logger, I recommend saving only as CSV files, not as either of its other file format options, as the speed is saved only in the CSV format, not in KMZ nor GPX.

The USGlobalSat BU-353N USB GPS Receiver serves as an example of option #2, a GPS receiver that works well with Tru-Traffic. It has some appealing features. It includes a magnetic mount, a water resistant casing, and a 5-ft USB cable so you can easily mount it on the roof of a vehicle with good exposure to the sky. It uses the SiRF Star III GPS chipset and an active patch antenna for high accuracy and sensitivity.

The older, end-of-life Qstarz BT-Q1000XT Bluetooth Data Logger GPS Receiver serves as an example that gives both option #1 & option #2, a device that can operate as a GPS "mouse" or a GPS data logger and works well with Tru-Traffic.

The figure below, taken from the User's Manual illustrates the penalty in the speed accuracy that you can incur using option #1, if your GPS receiver doesn't include the speed in its self-recorded trip logs. The associated discussion in the user's manual describes the cause and consequences in more detail. As of this writing, the figure is on page 54 in the user's manual.

¹Depending on how this GPS data logger is configured, this should store at least 25 hours of trip data.