Circuit for eliminating spurious components resulting from burst control in a TDMA system

摘要

In an electronic circuit comprising a modulator (35) and used in each substation of a TDMA system and responsive to a baseband data signal sequence for producing a burst in accordance with a first burst control pulse, spurious components resulting in the burst from the first burst control pulse are eliminated either by allowing the data sequence to pass through a low-pass filter (36) after switching (45) the sequence by the first burst control pulse or by filtering the first burst control pulse by a low-pass filter before switching a local oscillation signal by the first control pulse. An additional switching circuit may switch either a modulated signal supplied from the modulator or the local oscillation signal in response to a second burst control pulse that disappears after extinction of the first burst control pulse. Alternatively, a modifying circuit reverses polarities of a preceding and a following data signals immediately preceding and following the sequence, relative to a leading and a trailing end data signals of the sequence.