Title:
DIGITAL FREQUENCY DIVIDING METHOD AND DEVICE
Document Type and Number:
Japanese Patent JPS5486258
Kind Code:
A
Abstract:
Division by non integral ratios is often required for carrier generation in communications systems. Such division - i.e. multiplication by Z/N < 1 (e.g. 11/62) is commonly effected by dividing by N and using the Zth harmonic of the resultant output. As the harmonic content decreases with increasing Z, the invention aims to increase the desired harmonic component, so as to reduce the requirements for subsequent filtering. Thus a frequency divider is employed and its division ratio is varied in suitable manner during N input periods; limitations are also imposed on the symmetry of the output waveform. The output waveform can be so arranged as to make its frequency spectrum rich in the desired harmonic, whilst reducing the adjacent, unwanted harmonics. A divider apparatus is also proposed, with a programmable divider (R, LS) and gate (A) which receives the input pulses and drives an output flip-flop (H) and counter means (T1, T2) which produce control signals (SI, SII) with which the divider is programmed. The divider may, for example, count 21 DIVIDED 2, 3 and 31 DIVIDED 2 impulses.
Inventors:
POELZL ADOLF
SONNTAG FRITZ
SONNTAG FRITZ
Application Number:
JP14668278A
Publication Date:
July 09, 1979
Filing Date:
November 29, 1978
Export Citation:
Assignee:
SIEMENS AG
International Classes:
H03K21/08; H03K23/00; H03K23/64; H03K23/58; H03K23/66; H03K23/68; H04J1/06; (IPC1-7): H03K21/36; H03K23/24