SR120U-UHF(SR_FRS_2WU) is a wireless voice intercom and data transmission module with extremely high cost performance. It integrates a high-performance RF transceiver chip, microcontroller, and RF power amplifier. The external controller can set the working parameters of the module and control the transmission and reception of the entire module through a standard asynchronous serial interface (RS232). This module only needs to be connected to an antenna, microphone and audio power amplifier to form a complete walkie-talkie or data transmission radio.
Features:
- Digital signal processing based frequency modulation and demodulation technology
- Frequency range: 400MHz~470MHz
- Selectable frequency stepping: 5K/6.25K/12.5K/25K
- 3 selectable RF output power: High power 2W, Medium power 1W, Low power 0.5W
- Voice encryption (scrambler) function: (8 options)
- Short message SMS transmission and reception
- Built-in CTCSS (38 groups) and CDCSS (83 groups) encoder/decoder
- Automatic tail elimination
- Digital volume adjustment: (1-8 levels) adjustable
- Voice control handsfree trigger sensitivity: (0-8 levels) adjustable
- Noise suppression level: (0-9 levels) adjustable
- MIC sensitivity adjustment: (1-8 levels)
- High receiving sensitivity: -122dBm
- Ultra low power consumption (sleep mode): (0.1uA)
- Operating voltage range: 3.3V~5.0V, recommended 3.7V-4.5V
- Ultra compact size: 17*28.5*3.0mm
- Reference communication distance: 3-5 km in open area; actual distance depends on many factors.
Applications:
1. Portable walkie talkie and paging systems
2. Wireless data transmission (SMS) systems
3. New designs with embedded walkie talkie functionality in mobile phones and other products
Module pin assignment
| Pin Number |
Pin Name |
Function Description |
Notes |
| 1 |
NC |
Programming pin (I/O) |
Do not connect |
| 2 |
NC |
Programming pin (I/O) |
Do not connect |
| 3 |
NC |
Programming pin (I/O) |
Do not connect |
| 4 |
AF |
Audio output |
|
| 5 |
MIC |
Microphone input |
|
6 |
HML |
RF high/medium/low power control; GND for low power 0.5W, float for high power 2W, 1.5V input for medium power 1W; |
Currently only supports 2W/0.5W software configuration |
| 7 |
ANT |
RF input/output |
|
| 8 |
GND |
GND |
|
| 9 |
GND |
GND |
|
| 10 |
VBAT |
Power supply positive 3.3V-5V |
Recommended 3.6-4.3V |
| 11 |
TX |
Voice control handsfree trigger indicator output, high: triggered; low: no trigger |
|
12 |
RXD |
Asynchronous serial interface (receive data) Note: For MCU control applications, this pin must be pulled up externally. |
If RXD is pulled low for over 50ms, it will enter production test mode. |
| 13 |
PTT |
Transmit/receive control pin, 1=receive, 0=transmit |
|
| 14 |
SPK |
Noise suppression control output, active low |
|
| 15 |
TXD |
Asynchronous serial interface (transmit data) |
|
| 16 |
PD |
Module sleep enable pin, 0=SLEEP |
Module can only work when connected to high level |
| 17 |
+3V |
Module +3V output, for small external current use (<5mA) |
Do not connect large load |
| 18 |
GND |
GND |
|
Typical application Block diagram
See the pictures.
Useful Link:
AT Command for UHF/VHF Walkie Talkie radio module
