400-440 MHz UHF Radio Modem

GD420HH25 is a half-duplex UHF radio modem that operates on 400 to 440 MHz frequency band. Channel spacing 12.5 and 25 kHz are available, with over-the-air data rates 9600 bps in 12.5 kHz channel spacing or 19200 bps in 25 kHz channel spacing, respectively. The radio modem is compatible with the most widely used serial interfaces RS-232, RS- 485 and RS-422. With output power of 25 watts, It meets both the technical and economical requirements set on wireless communications in a number of applications, including remote meter reading (gas, electricity, heat), remote control of water distribution, remote control of irrigation systems and environmental monitoring.

Specifications

1. General 
   (1) Operating frequency range: 400 to 440 MHz 
   (2) Channel spacing: 25 KHz or 12.5KHz
   (3) Number of channels: 60
   (4) ANTENNA IMPEDANCE: 50 Ohm unbalanced
   (5) OPERATING TEMPERATURE: -40 to +70℃
   (6) FREQUENCY STABILITY TCXO:   ±1.5ppm
   (7) OPERATION VOLTAGE RANGE: 12V DC ( 11Vdc to 14.5V  DC)
   (8) STAND-BY CURRENT: 85mA

2. TRANSMITTER 
   (1) RF OUTPUT POWER: 5W to 25W programmable
   (2) OUTPUT 2ND HARMONIC: less than –65dB
   (3) SPURIOUS EMISSIONS:  less than 0.25uW (30MHz to 1GHz)
   (4) MAXIMUM FREQUENCY DEVIATION: ±5KHz
   (5) REFERENCE OSCILLATOR: TCXO
   (6) RF IMPEDANCE: 50 Ohm unbalanced
   (7) CURRENT DRAIN: 6.0A @25W output power
   (8) FM HUM AND NOISE RATIO: greater than –50dB
   (9) AUDIO FREQUENCY DISTORTION: 3% 1KHz for 3KHz deviation 
   (10) AUDIO FREQUENCY RANGE: 300Hz to 3400Hz ±2dB
   (11) TRANSMITTER ATTACK TIME: less than 7ms

2. RECEIVER 
   (1) TYPE OF RECEIVER: Crystal controlled double, super heterodyne
   (2) INTERMEDIATE frequency: 45MHz(1st IF), 455KHz(2nd IF)
   (3) SENSITIVITY: Better than 0.2uV @12dB SINAD
   (4) SQUELCH SENSITIVITY: 0.1uV to 1uV programmable
   (5) ADJACENT CHANNEL SELECTIVITY: greater than –70dB
   (6) SPURIOUS AND IMAGE REJECTION: greater than –65dB
   (7) OUTPUT AUDIO DISTORTION: 3% at 1KHz for ±5KHz deviation
   (8) FM HUM AND NOISE RATIO:  greater than 40dB

3. Data and Interface 
   (1) MODULATION: GMSK
   (2) AIR RATE: 19200 or 9600bps programmable 
   (3) INTERFACE BAUD RATE: 600 - 38400 bps programmable
   (4) INTERFACE DATA BIT: 8 / 7  bit
   (5) INTERFACE PARITY BIT: None / Even / Odd
   (6) INTERFACE STOP BIT: 1 / 2  bit