# FM radio transmitter module, DSP PLL, 87–108 MHz, LCD, campus mode 76–108 MHz - Page: https://sigmanortec.ro/en/fm-radio-transmitter-module-dsp-pll-87108-mhz-lcd-campus-mode-76108-mhz - Price: 62.13 RON - Availability: In stock; 1-2 zile - Reference: 88307 · EAN: 5948723808075 - Category: Mechatronics and IoT > Sensors and Modules > RF and Radio Modules - Specifications: Supply voltage: 3-5 V DC; Type: Stereo FM transmitter with DSP and PLL; Operating temperature: -30 ~ 85 °C; Interface: TTL serial; Operating frequency: 87.0-108.0 MHz, mod campus 76.0-108.0 MHz; Output power: 100 mW; Power consumption: 35 mA; Display: LCD; Antenna: 75 cm rod or wire, connected to the ANT port; Signal-to-noise ratio: minimum 30 dB; Modulation: FM standard; Frequency response: 50 Hz - 18 kHz; Frequency tuning step: 0.1 MHz / 1.0 MHz - Updated: 2026-10-26 - Shop: [Sigmanortec.ro](https://sigmanortec.ro/en/llms.txt) - Prices: RON, VAT included; prices and stock as of 2026-11-11 01:49 (Europe/Bucharest) ## Description FM radio transmitter module with DSP and PLL technology, with LCD display and 5 buttons, transmits stereo on the 87.0 - 108.0 MHz band or, in campus mode, on the 76.0 - 108.0 MHz band, with an output power of 100 mW. It accepts audio signal from LINE, USB, or the built-in MIC microphone, is powered by 3.0 - 5.0 VDC, and uses a 75 cm antenna. Suitable for wireless microphone, audio broadcasting from a phone or PC, and short-range DIY broadcasting projects. This FM radio transmitter module uses digital signal processing (DSP) technology and a phase-locked loop (PLL) to transmit the signal without frequency drift and with good sound quality. It accepts audio from a stereo LINE input, from the micro USB port (PC sound card), or from the built-in electret microphone on the MIC channel, making it suitable for wireless microphones, audio broadcasting from a phone or computer, audio surveillance, and other short-range FM transmission projects. The transmitter has an output power of 100 mW and covers the standard 87.0 - 108.0 MHz band, extended to 76.0 - 108.0 MHz in campus mode (campus radio), for university stations that broadcast below the commercial band limit. The frequency is adjusted with the FRE- and FRE+ buttons, in 0.1 MHz steps with a short press and continuously, in 1.0 MHz steps, with a long press, and the volume is adjusted digitally, in 30 levels, with the VOL- and VOL+ buttons. The modulation is standard FM, the audio frequency response is 50 Hz - 18 kHz, and the signal-to-noise ratio is at least 30 dB. On the back of the board there are two solder pads, M and G, through which transmission can be switched from stereo (default, open bridge) to mono (shorted bridge). Among the main features are the backlit LCD display, the 5 buttons VOL-, VOL+, FRE-, FRE+ and PAUSE (the latter for mute/unmute), the micro USB port for audio from a PC, the LINE input for external audio sources, the built-in MIC microphone, the ANT port for the antenna, and the TX, RX and GND serial pins for external control via TTL interface. The module retains in memory the last frequency and the last volume set, even after power is turned off. Power supply is 3.0 - 5.0 VDC, with a current consumption of 35 mA, preferably from a battery or from a regulated and filtered power supply, not from an unfiltered phone charger, because power-supply noise affects transmission. Through the micro USB port, the module connects directly to a computer, which recognizes it as a sound card and can transmit over FM whatever the operating system plays. Through the TX, RX and GND serial pins, with TTL level, the module can be remotely controlled by a microcontroller such as Arduino, ESP32 or STM32, or from a computer through a USB-TTL adapter. Specifications: Supply voltage: 3.0 - 5.0 VDC Consumption: 35 mA Module type: Stereo FM transmitter with DSP and PLL Output power: 100 mW Frequency band (closed campus): 87.0 - 108.0 MHz Frequency band (open campus): 76.0 - 108.0 MHz Frequency adjustment step: 0.1 MHz (short press) / 1.0 MHz (long press) Modulation: Standard FM Audio frequency response: 50 Hz - 18 kHz Audio channels: LINE and USB (stereo), MIC (mono, built-in electret microphone) Signal-to-noise ratio: minimum 30 dB Volume adjustment: digital, 30 levels, with memory after power off Stereo/mono selection: M and G solder pads on the back of the board (open bridge = stereo, shorted = mono) External control: TX, RX, GND TTL serial pins for commands from a microcontroller or computer Antenna: 75 cm rod or wire, connected to the ANT port Operating temperature: -30 ~ 85 degrees Celsius Layout: Element Function 3.0-5.0V power pins ("-" and "+") Supplies the board with 3.0 - 5.0 VDC, observing the marked polarity. USB port Micro USB connector for audio from a computer and for 5V power supply. MIC pins Input for the built-in stereo electret microphone on the board. LINE pins Stereo line-level audio input for connecting an external source. LCD display Shows the current frequency, volume level, and campus mode status. VOL- button Decreases the volume, by 1 step with a short press and continuously with a long press. VOL+ button Increases the volume, by 1 step with a short press and continuously with a long press. FRE- button Decreases the transmission frequency, by 0.1 MHz with a short press and continuously, by 1.0 MHz, with a long press. FRE+ button Increases the transmission frequency, by 0.1 MHz with a short press and continuously, by 1.0 MHz, with a long press. PAUSE button Toggles transmission between mute and unmute. ANT antenna (back) Pad for connecting the 75 cm antenna, also accessible through the hole on the front of the board, next to the PAUSE button. M and G pads (back) Stereo/mono selection by shorting the two solder pads. TX, RX, GND pins (back) TTL serial interface for external control from a microcontroller or computer. Pinout: Connector Pin Function Power Negative power supply, 3.0 - 5.0 VDC Power + Positive power supply, 3.0 - 5.0 VDC USB micro USB Audio from computer and 5V power supply MIC Built-in stereo electret microphone input LINE Stereo line-level audio input ANT RF output, for connecting the 75 cm antenna TTL Serial (back) TX Module TTL serial output TTL Serial (back) RX TTL serial input, for control commands TTL Serial (back) GND Common ground for the serial port Jumper (back) M Solder pad for mono selection, shorted with G Jumper (back) G Ground for jumper M, normally unconnected (stereo) Buttons VOL- Decrease volume Buttons VOL+ Increase volume Buttons FRE- Decrease frequency Buttons FRE+ Increase frequency Buttons PAUSE Mute / unmute Action on startup Result Normal power on, with no buttons pressed The module starts on the last frequency and last volume used, in the previously set band Hold VOL- and VOL+ simultaneously while connecting power Switches the transmission band: LCD shows C1 for the extended 76.0 - 108.0 MHz band (open campus) or C0 for the standard 87.0 - 108.0 MHz band (closed campus), and the setting remains active after restart Use: Connect the module’s "-" and "+" terminals to a battery or to a regulated and filtered power supply, with a voltage of 3.0 - 5.0 VDC, observing the polarity marked on the board. Do not exceed 5.0 VDC and do not use an unfiltered phone charger, because noise from a poor-quality power supply affects transmission clarity. Attach a 75 cm antenna to the ANT port and orient it as far as possible from obstacles for optimal transmission. Connect the audio source to the LINE input with a 3.5 mm stereo cable, from a phone or other audio equipment, or connect the module to a computer via the micro USB cable to transmit the operating system sound. If no cable is connected to LINE or USB, the module automatically transmits the sound picked up by the built-in MIC microphone. Set the desired frequency with the FRE- and FRE+ buttons, using a short press for 0.1 MHz steps and a long press for continuous adjustment with 1.0 MHz steps, then adjust the volume with VOL- and VOL+ and use PAUSE to temporarily stop audio transmission. To activate the extended campus band (76.0 - 108.0 MHz), turn off the power, then hold VOL- and VOL+ simultaneously while reconnecting power until the LCD shows C1. Repeat the procedure to return to the standard band (87.0 - 108.0 MHz), in which case the LCD will show C0. For mono transmission instead of stereo, short the M and G pads on the back of the board. Leave them unconnected for stereo transmission. For remote control, connect the TX, RX and GND pins to a microcontroller or, via a USB-TTL adapter, to the serial port of a computer. Tune an FM receiver to the same frequency shown on the module’s LCD to listen to the transmitted signal.