An Example of Notch Filter Design Spec for the IM Noise Signal Cancellation in 800 MHz CDMA Frequency Band

Recently, the 700 MHz frequency band for the wireless radio systems and UHF TV broadcasting system are newly reallocated in our country. And also, the conventional frequency band of 700 MHz is redistributed by the government spectrum policy and new CDMA mobile radio frequency band has been reallocated. Therefore, it is necessary to analyze and understand the mutual interference problems between adjacent wireless systems. In this paper, to investigate of interference signals inducing in CDMA systems from the adjacent wireless systems we measured and analyzed IM (Intermodulation) noise signals which those unwanted signals are concerned to the adjacent RF interference signals. Especially, we designed a Notch filter to reject the IM noise signals from the RF repeater and boosters of UHF TV broadcasting systems, and then evaluated the filter application effects.