Test Traffic Measurements - FAQ

How can we see if the antenna is positioned correctly?

Install the antenna in such a way that faces at least half of the sky. After a while (10 minutes to a few hours), you should see several satellites. If you don't then the signals are too weak or noisy.

• See our Demo Test Box for more info

We have placed the GPS receiver behind a window and no satellites are seen?

The GPS receiver might see a handful of satellites but the signals could be too weak or noisy to determine its position and thus the local time and your coordinates. If you can open the window, then it might be useful to put the antenna outside the window for a couple of hours. This often helps: the receiver gets a good position fix and can then survive with a noisier signal once the antenna is put back inside.

Can we share the antenna with another application

The short answer: No, you cannot.

The long answer: The antenna is an active unit that is being controlled by the PC, with communication flowing in both directions. If 2 receivers are connected to the antenna, both will try to control it. The antenna will be totally confused.

There are products on the market that allow users to share a Trimble antenna. One example is a TDS2 unit from Endace. This unit splits the signals from the antenna into multiple channels. You should configure the set-up such that the TTM box has bi-directional communication with the antenna. Other boxes using the signal should just listen to the signals on the wires. We do not have any experience with this unit, so you will have to do some experimentation yourself. All this is done at your own risk.

Another option would be to install a GPS-reradiation unit in your machine room. This is a unit that receives a GPS signal and re-broadcasts it in your room. All applications can use their own GPS antenna, but you will not have to climb on the roof every time something changes in your setup. Such units are available from (a.o). NavTech GPS. Contact us if you need more information.