Demodulator circuit in DTB Digital Terrestrial Broadcasting and public address receiver

摘要

One digital terrestrial broadcast and public address receiver disclose in which hardware realization is simplified. In this demodulator circuit, analog/digital conversion unit is the intermediate-freuqncy signal for being converted to a digital signal by channel reception, and the intermediate-freuqncy signal that the demodulation of variable rate demodulator is exported from analog/digital conversion unit is to generate baseband I and Q signal conversion. First and second SQRC filters/FFE uses the baseband I and Q signal that export from variable rate demodulator using a scheduled filter coefficient to remove noise and linear interference, and DFE removes first and second SQRC filter and exports a signal obtained by cursor after removing. First and second subtracter calculates difference, it is in first and second SQRC filter/between the output quantity of FFE and the output quantity of DFE, first and second slicer determines the signal that export from first and second subtracter, and the execution of FEC decoders is from the forward error correction on the signal that first and second slicer exports. Filter coefficient control unit controls first and second SQRC filters/FFE and DFE filter coefficient according to initial operation mode and normal operation mode. According to this configuration, since SQRC filtering functions and FFE functions are implemented as a by-pass filtration, filter coefficient update is done according to including being removed simultaneously by control receiving initial operation mode in signal and normal operation mode, noise and interference.