A method to withstand high signal attenuation for infrared electronic-toll-collection systems—Equivalent strength of the received signal in the communication area

High signal attenuation for the infrared signal of some windshields is a serious problem for infrared electronic-toll- collection (ETC) systems. This leads to severe shrinkage of the communication area if the emitter has not been properly designed. An equal value of the received signal strength in the communication area has the advantage of keeping the communication range independent of a limited signal attenuation. This is manifested in this paper by investigating the bit error rate (BER) of the system related to the received signal strength. Systems with acceptable performance can be realized even with light emitting diodes (LEDs) with irregular radiation pattern. The system performance provided by our earlier designs are more deeply explored in this paper in terms of bit error rate.