Patent ID: 8325786
Filing Date: 2012-12-04
Classification: G06K,H04L

Abstract:
1. A semiconductor device comprising: a demodulation circuit for demodulating a modulated signal that is coded with a specified code type and is received at an antenna; and a reception logic circuit for decoding a demodulation signal that is output from the demodulation circuit, wherein the reception logic circuit determines one of a plurality of code types for the demodulation signal and decodes the demodulation signal in accordance with a determined code type to reproduce reception data, wherein the code type is determined based on a difference between codes appearing in the demodulation signal during one of a modulation period and a non-modulation period, and wherein the demodulation signal is decoded in accordance with a determined code type based on a state of one of the modulation period and the non-modulation period alternately appearing in the demodulation signal, wherein the reception logic circuit comprises: a timer that measures one of the modulation period and the non-modulation period appearing in the demodulation signal; a determination section that determines the code type based on a measurement value measured by the timer; and a decode section that uses a result measured by the timer in accordance with the determined code type, decodes the demodulation signal, and reproduces reception data, wherein the code types mainly comprise Modified Miller, Non-Return to Zero (NRZ), and Manchester codes, wherein the determination section determines a NRZ code when the timer detects that the measurement value for the non-modulation period has exceeded a value equivalent to half an encode time unit for each of Modified Miller and NRZ codes during the modulation period in the demodulation signal, wherein the determination section determines a Modified Miller code when the demodulation signal enters the non-modulation period before exceeding the value equivalent to half the encode time unit and the measurement value for the non-modulation period is detected to exceed the value equivalent to half the encode time unit during the non-modulation period, and wherein the determination section determines a Manchester code when the demodulation signal reenters the modulation period before the measurement value for the non-modulation period exceeds the value equivalent to half the encode time unit.