Features: Advanced digital o signal processing (DSP) and FM phase-locked loop modulation technique (PLL) ensure less sound distortion and more stable performance. LCD display is more intuitive and accurate, with very low power consumption and minimal noise interference. Built-in 30-step digital volume adjustment allows easy volume control via buttons. Automatically stores data when power is off. Automatically switches between multiple o inputs. Uses quartz crystal for frequency stabilization, ensuring emission frequency does not drift with temperature changes. Supports serial port command control. Specifications: Output Power: 100mW Frequency Response: 50Hz to 18kHz Emission Frequency: 87.0MHz to 108.0MHz (closed campus broadcast), 76.0MHz to 108.0MHz (open campus broadcast) Frequency Adjustment: 0.1MHz per button press, 1.0MHz per long press Modulation Mode: Standard FM o Channels: LINE/USB (stereo), MIC (mono) Equivalent Noise: ≥30dB Input Voltage: DC 3V to 5V Current: 35mA Transmission Distance: 100 meters (for reference only, tested with 75cm antenna on open ground) Module Size: 49 x 26.5mm (1.93 x 1.04 inches) Display Size: 24 x 15mm (0.94 x 0.59 inches) Compatible with: FM radio, wireless microphone, computer o transmission (via USB connection) Wiring Instructions: 1. Use battery or regulated linear power supply. Do not use switch-mode power supplies such as power banks, phone chargers, or unfiltered DC-DC modules, as high-frequency interference may affect module performance. 2. For USB o broadcast, connect the module to a computer using a USB cable. The computer will detect the device as "CD002" o equipment. Enable this output in system o settings to transmit computer o via FM. 3. For LINE input, connect one end of an o cable to the 3.5mm jack and the other to an o source (e.g., mobile phone). The module will automatically switch to LINE mode. 4. For MIC input, disconnect USB and LINE cables. The module will automatically switch to MIC mode. The built-in electret microphone supports wireless microphone applications. Adjust volume for optimal pickup. 5. The module includes a TTL-level serial interface (UART_RX, UART_TX, GND). Connect using a compatible TTL serial source such as a microcontroller or computer with a USB-to-TTL adapter. Note: standard computer serial ports require a level converter. Serial control requires technical knowledge and is optional. User Settings: 1. Backlight Setting: Press and hold "FRE+" and "FRE-" while powering on. Display "B1" enables constant backlight; "B0" enables 20-second backlight timeout. Restart to apply (default: B0). 2. Campus Broadcast Setting: Press and hold "VOL+" and "VOL-" while powering on. Display "C1" enables open band (76–108MHz); "C0" limits to 87–108MHz. Restart to apply (default: C0). 3. Stereo/Mono Mode: Two solder pads labeled "M" and "G" on the back. Short these pads for mono transmission; leave open for stereo (default). o source and receiver must support stereo for stereo effect. Notes: - Input voltage must be DC 3V to 5V. - Avoid touching circuit components during operation to prevent malfunction or damage due to short circuits. Package Includes: 1 x Module Note: New and old versions may be shipped randomly. Ensure acceptance before ordering.