| 摘要 |
<p>An object is to demodulate analog modulated and digitally modulated waves, and automatically switch to demodulate the digital modulated wave component when the reception quality becomes good while the analog modulated wave component is being demodulated. IF filters (1, 2) extract the analog modulated wave component and the digital modulated wave component from a modulated wave signal (Sin). The extracted components are frequency shifted at a frequency shifter section (3) and combined at a combining section (4) into a combined modulated wave signal (Shdaa), which is in turn converted at an analog-to-digital converter (5) to combined modulated wave data (Dhdaa). A band-pass filter (6) extracts data (Dd) corresponding to the digital modulated wave component from the combined modulated wave data (Dhdaa), so that a digital broadcast demodulation section (8) demodulates the data (Dd). A band-pass filter (7) extracts data (Da) corresponding to the analog modulated wave component from the combined modulated wave data (Dhdaa), so that an analog broadcast demodulation section (9) demodulates the data (Da). In accordance with an error sense signal (ERR) detected at the digital broadcast demodulation section (8), a reception quality decision section (10) determines whether or not the reception quality is good. When the reception quality is good, a digital broadcast demodulated data (DMd) is output via a switching section (11), whereas when the reception quality has degraded, an analog broadcast demodulated data (DMa) is output via the switching section (11).</p> |
