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