Mitigation method/Results/Conclusion The following countermeasures were performed to reduce the interference signal from the telecommunication equipment: a) covering the building wall with shielded sheets (see Figure 1.12-4), and b) clamping ferrite cores on cables connected to the transmission equipment. After taking these countermeasures, the level of the interference signal decreased from 22 dB to 11 dB. As a result, the D/U ratio became more than 40 dB and the TV interference disappeared (see Figure 1.12-5). Detached house in which an interference occurred Covering with shielded sheets 60 Audio signal Video signal Received level [dBμV] Interference signal 40 Main street 20 0 210 212 214 216 Frequency [MHz] Miti(08)_F1.12-5 Figure 1.12-5 – Measured spectrum after Miti(08)_F1.12-4 Direction of TV broadcasting wave countermeasures Figure 1.12-4 – Configuration of countermeasure – 3 – Case study 1.12