Keyed AGC circuit for video data transmitting device
AssigneeFuji Xerox Co., Ltd.
InventorsFumio Miyao, Kazumi Tsukioka
Life of this patent
Estimating the term…
Abstract
A keyed AGC circuit for use in a video data transmitting device such as a facsimile system which operates stably in the presence of external noise. A processing circuit is provided for carrying out digital processing determining whether the synchronizing signal level at an output terminal of the AGC circuit is higher or lower than a pre-set reference level. A multi-stage digital attenuator is controlled in response to outputs of the processing circuit to set the attenuation level. Control of the multi-stage digital attenuator can start with either the most significant bit position of the attenuator prior to video data transmission or with a least significant bit position of the attenuator in a synchronization period after video data transmission has been started.
Claims5
A keyed AGC circuit for a video data transmitting device comprising:
- a process circuit for carrying out a digital process to determine whether a synchronizing signal level at an output terminal thereof is higher than or lower than a reference level;
- and a multi-stage digital attenuator coupled to be controlled in response to an output of said processing circuit, said processing circuit comprising means for setting an attenuation level of said attenuator in a plurality of successive steps in accordance with said synchronizing signal level.
Dependencies are inferred from the claim text.