Disclosed is a communication apparatus having a small-scale circuit used for modulation. Each sensor comprises a recognition module and a sensor signal transceiver module. The method can include multiplying the set rounded quantized background wavelet transform coefficients by the second quantizer and rounding all wavelet transform coefficients. The data length and packet count randomly and dynamically change during the communication session and varies from one transaction to another transaction. The restricting member is disposed in the through hole.