PURPOSE: To ensure a proper threshold level and to decrease the data error after conversion even when the state of a signal is defective by adjusting automatically the threshold level in response to the input signal level.
CONSTITUTION: A threshold level processing section 1 receives an input ternary data IN and compares it with a prescribed threshold level and a ternary/binary conversion section 2 uses a prescribed conversion table to convert the ternary data into a binary 3-bit data. Threshold levels TL, TM, TH are provided on the processing section 1. The level TM is selected to be nearly between the levels TH and TL, an area corresponding to the level 1 of the ternary data is divided into two areas 1a, 1b and the area being ≤TL/≥TH is set to an area equivalent to 0, 2 respectively. The conversion section 2 outputs a binary 3-bit data in a normal area in the conversion table as a binary data as it is, and outputs an abnormal data continuing data 1 after converting it in response to the areas 1a, 1b and uses the threshold level adjustment section 3 to adjust the threshold level. Thus, the data error after the conversion is reduced.
TAMAKI KAZUHIDE
NINOMIYA YUICHI
OTSUKA YOSHIMICHI
JAPAN BROADCASTING CORP