400-440MHz 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 bpsin 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