After finishing up the last bits of the project to install coverage in the Stockholm underground Metro system there has now been a drive test conducted.

This is a short video showing some of the activities and some pictures from this more fun side of the job.

For the more technical people out there I can tell you that we are actually measuring several radio services:

Train communication radio

• RAKEL – swedish blue light services radio
• Busskom – Our own TETRA network
• SplitZone – Our own new TETRA network that will in time replace Busskom
• FM Broadcast – For public service, commercial stations as well and important messages to the public

We also had a visit from the mobile operator Tre that conducted drive test measurement on their 3G network with good results.

The test equipment consists of the following:

• Laptop logging all the data
• Doppler radar mounted under the train that gives us the trains movement as 400 clicks per meter. This is connected to a small PIC processor that calculates the current distance always that can be queried from the laptop when necessary to get the current distance.
• Rhode & Scwarz ESPI test receiver, capable of measuring many frequencies at the same time, in this test we did 19 channels with 7-10 samples per second.
• GPS for accurate time synchronization
• Antennas for the various bands being measured
• Signal generators for uplink signal
• Amplifiers for the uplink signal to match the levels generated by the train radios
• Test receivers at the base stations to receive the uplink signals and log them with the same time reference