VERFAHREN ZUR TON-SIGNALVERARBEITUNG BEI EINEM MEHRNORMEN-FERNSEHEMPFAENGER

摘要

In multi-standard television receivers, in which the second audio intermediate frequency is converted into a constant frequency regardless of the current reception standard, external filters and demodulators of very high quality and selectively are needed for filtering and demodulating the second audio intermediate frequency. The purpose of the invention is to process audio intermediate frequencies more simply. Upstream of the mixing stage which converts the first into the second audio intermediate frequency there is a filter, the bandwidth of which is tuned to the entire frequency spectrum of the first audio intermediate frequency and serves for preselection and downstream of the mixing stage there is a filter arrangement which is tuned to the frequency spectrum of the second audio intermediate frequency and produces a fine-selection of the second audio intermediate frequency.