Main technical indicators:
1. communication mode: AM
2. Working frequency: 316.8mhz.
3. Frequency stability: 75KHZ
4. Receiving sensitivity:-102DBM
5. Static current: ≤5MA
6. Working current: ≤5MA
7. Working voltage: DC 5V
8. Output mode: TTL level
The superheterodyne receiving module provided here adopts imported high-performance wireless remote control and data transmission ASIC RX33 10A and 3 16.8M acoustic resonator, which is stable and reliable and suitable for all-weather operation in harsh environment.
Introduction of RX33 10A integrated circuit;
RX33 10A is a wireless remote control and digital signal receiving integrated circuit produced by HMARK Company in Taiwan Province Province, which is specially used for AM-keying ASK modulation. It includes low noise high frequency amplifier, mixer, local oscillator, intermediate frequency amplifier, intermediate frequency filter, comparator and so on. It is a primary frequency conversion superheterodyne circuit, which is packaged in a double-row 18 pin wide chip. The main technical indicators are as follows:
Operating frequency: 150 ~ 450 MHz
Working voltage: 2.7 ~ 6V
Working current: 2.6 mA (under 3V power supply)
Receiving sensitivity:-105 DBM (1K data rate and antenna matching)
Maximum data rate: 9.6KBPS
The signal received from the external antenna is coupled to the frequency selection network composed of L3 and C9 to C8, and then input to the input end 14 of the internal high-frequency amplifier of RX33 10. The high-frequency amplified signal in the chip (the gain is 15 ~ 20 dB) is mixed with the local oscillator signal (3 16.8M) by a mixer to generate1.8m.
The superheterodyne receiver requires high impedance matching of the antenna, and the impedance of the external antenna must be 50 ohms, otherwise it will have a great influence on the receiving sensitivity. Therefore, when using the common wire with the wavelength of 1/4, it should be 23 cm, so as to minimize the lead length from the antenna root to the antenna welding point of the transmitting module. If it can't be lowered, it can be connected by RF coaxial cable with characteristic impedance of 50 ohms (there is a special grounding solder joint on the right side of antenna solder joint).