radio modem with RS232 at 1200bps air rate

GDM212 is an 1200bps air rate radio modem with RS232 serial port. The radio unit can operate as a transparent radio link, essentially replacing a wire with classic RS-232 based protocol. It is designed for long rang telemetry, SCADA and remote control application under different weather conditions.

Depending on these radio modems, the range of RS-232 communication can be extended up to 20 miles or more in pure line-of-sight conditions. GDM212 has 12V or 24V operating voltage levels to chose from and low power consumption, it is extremely well suited for outdoor use.

Specifications

1. General 

(1)OPERATINGFREQUENCYRANGE: 136 to 150MHz

(2) Channel spacing: 25 KHz

(3) Number of channels: 16
(4) ANTENNA IMPEDANCE: 50 Ohm unbalanced
(5) OPERATING TEMPERATURE: -40 to +70℃
(6) FREQUENCY STABILITY TCXO:  ±2.5ppm
(7) OPERATION VOLTAGE RANGE:12V or 24V 
( 8) STAND-BY CURRENT: 110mA
2. TRANSMITTER

(1) RF OUTPUT POWER: 1.5W programmable

(2)RECEIVER ATTACK TIME: 20ms

(3) AUDIO FREQUENCY RANGE: 300Hz to 3400Hz ±2dB

(4) SPURIOUS EMISSIONS: less than 0.25uW (30MHz to 1GHz)

(5) OUTPUT 2ND HARMONIC: less than –65dB

(6) MAXIMUM FREQUENCY DEVIATION: ±5KHz

(7) REFERENCE OSCILLATOR: TCXO

(8) RF IMPEDANCE: 50 Ohm unbalanced

(9) FM HUM AND NOISE RATIO: greater than –50dB (under normal condition)

2. RECEIVER 
(1) TYPE OF RECEIVER:Crystalcontrolled double, super heterodyne
(2) INTERMEDIATE frequency: 45MHz (1st IF), 455KHz (2nd IF)
(3) SENSITIVITY(12 dB SINAD) : Better than 0.2uV

(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 1 KHz for ±5KHz deviation
(8) FM HUM AND NOISE RATIO:  greater than 40dB

3. Data and Interface 

 (1) MODULATION: FSK
 (2) AIR RATE: 1200bps  programmable
 (3) INTERFACE DATA BIT: 8/7 bit
 (4) INTERFACE PARITY BIT: None / Even / Odd
 (5) INTERFACE STOP BIT: 1 bit