446 MHz Mosque Audio Link

Project Overview: Design and prototype a 446 MHz wireless audio broadcast system for indoor mosque sound in India (using the license-free PMR446 band). 1. Mosque Transmitter Unit: - Audio line-in from Mosque PA amplifier (Ahuja). - MAX9814 AGC leveler/compressor to prevent voice clipping or distortion. - Auto-VOX sound trigger to start transmitting automatically when the Muazzin speaks (zero manual buttons). - SA818S-U UHF module (1W Tx mode) tuned to 446.0562 MHz with 67.0 Hz CTCSS tone. - 50-ohm SMA connector connecting to outdoor Diamond X-50 minaret antenna via 15m RG-213 cable. - 5V DC power supply with surge protection. 2. Home Receiver Speaker Box: - SA818S-U module (Rx mode) tuned to the same 446.0562 MHz + 67.0 Hz CTCSS code. - Hardware squelch/mute control: MUST be 100% dead silent during standby (no hiss/static). Unmutes instantly when Azan transmits. - PAM8403 3W Class-D audio amplifier with rotary volume potentiometer and power switch. - 3-Watt 4-Ohm full-range vocal speaker. - 5V USB Type-C power input with onboard AMS1117-3.3V regulation. Deliverables: 1. Working bench prototype demonstration (1 Transmitter + 2 Receivers) with clear audio test video. 2. Complete Schematics & PCB Gerber files in KiCad or EasyEDA (ready for JLCPCB manufacturing). 3. Complete Bill of Materials (BOM) with verified part numbers and Indian sourcing links. 4. Setup firmware/code for initializing the SA818S module via UART.