The integrated circuit is coded, and a data modulation transistor Q1 is added. This structure makes it easy to interface with other fixed coding circuits, rolling code circuits and single-chip microcomputers without regard to the operating voltage of the coding circuit and the magnitude of the output amplitude signal value. . For example, when using a coded integrated circuit such as PT2262 or SM5262, connect the 17th pin of their data output terminal to the input end of the data module.
The data module has a wide operating voltage range of 3~12V. When the voltage changes, the transmitting frequency is basically unchanged, and the receiving module matched with the transmitting module can receive stably without any adjustment. When the emission voltage is 3V, the transmission distance is about 20~50 meters, and the transmission power is small. When the voltage is 5V, it is about 100~200 meters. When the voltage is 9V, it is about 300~500 meters. When the emission voltage is 12V, it is The best working voltage has a good emission effect, the emission current is about 60 mA, the transmission distance is 700~800 meters, and the transmission power is about 500 mW. When the voltage is greater than l2V, the power consumption increases, and the effective transmission power is no longer significantly improved. The feature of this module is that the transmission power is relatively large and the transmission distance is relatively long, which is more suitable for communication under severe conditions. The antenna is preferably a 25-cm-long wire. It is best to erect when transmitting over long distances. Because radio signals are transmitted by many factors, the practical distance is only half or less of the nominal distance. note.
The data module is modulated by ASK mode to reduce power consumption. When the data signal stops, the emission current drops to zero. The data signal and the input end of the transmitting module can be connected by resistor or directly without capacitive coupling, otherwise the transmitting module will not work normally. The data level should be close to the actual operating voltage of the data module to achieve a higher modulation effect.
The transmitting and transmitting module should preferably be mounted vertically on the edge of the motherboard and should be more than 5 mm away from the surrounding components to avoid distribution parameters. The transmission distance of the module is related to the frequency and amplitude of the modulation signal, the emission voltage and battery capacity, the transmission antenna, the sensitivity of the receiver, and the receiving and receiving environment. Generally, the maximum emission distance in the open area is about 800 meters. In the case of obstacles, the distance will be shortened. Since the refraction and reflection during radio signal transmission will form some dead zones and unstable regions, different receiving and receiving environments will be different. Send and receive distance.