are some commonly used encoder/decoder pair ICs. The encoder is used for encoding parallel data for transmission feed while the reception is decoded by a decoder. The RF module is often used along with a pair of encoders/decoders. The transmitted data is received by an RF receiver operating at the same frequency as that of the transmitter. The transmission occurs at the rate of 1Kbps - 10Kbps. The transmitter/receiver (Tx/Rx) pair operates at a frequency of 434 MHz An RF transmitter receives serial data and transmits it wirelessly through RF through its antenna connected at pin4.
Let us now see how the DHT11 transfer data from its single terminal. The DHT11 sensor can work from voltage of 3 volts to 5.5 volts. Two pins are for power supply, one is used for data communication and the last is left not connected. This RF module comprises an RF Transmitter and an RF Receiver. DHT11 pinout: As shown in the above figure that the DHT11 sensor has total four pins. RF communication uses a specific frequency, unlike IR signals which are affected by other IR emitting sources. Next, RF transmission is more strong and reliable than IR transmission. Also, while IR mostly operates in line-of-sight mode, RF signals can travel even when there is an obstruction between transmitter & receiver. Firstly, signals through RF can travel through larger distances making it suitable for long-range applications. Transmission through RF is better than IR (infrared) because of many reasons. This kind of modulation is known as Amplitude Shift Keying (ASK). In this RF system, the digital data is represented as variations in the amplitude of the carrier waves.
The corresponding frequency range varies between 30 kHz & 300 GHz. The RF module, as the name suggests, operates at Radio Frequency.
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