|Hans van der Marel
| The WSRT spectrum monitoring system is scanning continuously the RF spectrum from 20 MHz up to 3 GHz. It recorded the shutting down of the different transmitters at the Smilde TV-tower just before it collapsed on July 15. The waterfall plots show the signal strength in color as a function of time (in universal time, which means that local time is now 2 hours later) and frequency.
Several strong FM-signals suddenly disappear at about 13 hours UT as well as the five DVB-T channels that are transmitted from Smilde. Somewhat later also a number of GSM transmitters in the 900 MHz band are shut down.
After the collapse of the 300 m high Smilde tower, a 100 m high temporary tower has been constructed at the Johan Willem Friso military base in Assen. On July 23 the DVB-T transmitters in this temporary tower were switched on and in the evening of July 28 the FM-transmitters were started.
The measured signal strengths at the WSRT spectrum monitoring station of the transmissions from the temporary tower in Assen are slightly lower than they were from the Smilde tower.