ESP32-S3+LoRa对讲机桥接SIP网络对讲方案实现详解

ESP32-S3+LoRa实现SIP网络对讲及桥接对讲机的实现算法

ESP32-S3结合LoRa模块可以实现远距离通信，同时通过SIP协议实现网络对讲功能。桥接对讲机需要将LoRa的音频数据转换为SIP协议可识别的格式，反之亦然。

系统架构

LoRa模块：负责远距离音频数据传输，使用LoRa的扩频技术实现低功耗远距离通信。
SIP协议栈：用于实现网络对讲功能，处理呼叫建立、维护和终止。
音频编解码：将模拟音频信号转换为数字信号，常用编解码器如G.711、G.722。
桥接逻辑：将LoRa接收的音频数据转发到SIP网络，反之亦然。

关键算法

LoRa音频传输：使用LoRa模块发送和接收音频数据包，需考虑数据包大小、传输速率和纠错机制。
SIP信令处理：解析和生成SIP消息，处理INVITE、ACK、BYE等请求。
音频桥接：将LoRa音频数据转换为SIP RTP流，或将SIP RTP流转换为LoRa音频数据。

Python实现代码

LoRa音频收发

import time
from lora import LoRa

def lora_send_audio(lora, audio_data):
    # 分片发送音频数据
    chunk_size = 64
    for i in range(0, len(audio_data), chunk_size):
        chunk = audio_data[i:i+chunk_size]
        lora.send(chunk)
        time.sleep(0.1)

def lora_receive_audio(lora):
    audio_data = bytearray()
    while True:
        chunk = lora.receive()
        if chunk:
            audio_data.extend(chunk)
        else:
            break
    return audio_data

SIP信令处理

import socket
from sip import SIPMessage

def sip_handle_invite(sip_msg):
    # 解析INVITE请求
    if sip_msg.method == "INVITE":
        response = SIPMessage.create_response(200, "OK")
        return response

def sip_send_ack(sip_msg):
    # 发送ACK确认
    ack = SIPMessage.create_ack(sip_msg)
    sip_socket.send(ack.encode())

音频桥接

from rtp import RTPPacket

def bridge_lora_to_sip(lora_audio, sip_socket):
    # 将LoRa音频数据封装为RTP包并发送
    rtp_packet = RTPPacket(lora_audio)
    sip_socket.send(rtp_packet.encode())

def bridge_sip_to_lora(rtp_packet, lora):
    # 从RTP包提取音频数据并通过LoRa发送
    audio_data = rtp_packet.payload
    lora_send_audio(lora, audio_data)

C语言实现代码

LoRa音频收发

#include <lora.h>

void lora_send_audio(LoRa *lora, uint8_t *audio_data, size_t len) {
    size_t chunk_size = 64;
    for (size_t i = 0; i < len; i += chunk_size) {
        size_t remaining = len - i;
        size_t send_size = remaining < chunk_size ? remaining : chunk_size;
        lora_send(lora, &audio_data[i], send_size);
        delay(100);
    }
}

void lora_receive_audio(LoRa *lora, uint8_t *audio_data, size_t *len) {
    size_t received = 0;
    while (1) {
        uint8_t chunk[64];
        size_t chunk_len = lora_receive(lora, chunk, sizeof(chunk));
        if (chunk_len == 0) break;
        memcpy(&audio_data[received], chunk, chunk_len);
        received += chunk_len;
    }
    *len = received;
}

SIP信令处理

#include <sip.h>

void sip_handle_invite(SIPMessage *msg, SIPResponse *response) {
    if (strcmp(msg->method, "INVITE") == 0) {
        sip_response_init(response, 200, "OK");
    }
}

void sip_send_ack(SIPMessage *msg, int sockfd) {
    SIPMessage ack;
    sip_ack_init(&ack, msg);
    send(sockfd, &ack, sizeof(ack), 0);
}

音频桥接

#include <rtp.h>

void bridge_lora_to_sip(uint8_t *lora_audio, size_t len, int sip_socket) {
    RTPPacket packet;
    rtp_packet_init(&packet, lora_audio, len);
    send(sip_socket, &packet, sizeof(packet), 0);
}

void bridge_sip_to_lora(RTPPacket *packet, LoRa *lora) {
    lora_send_audio(lora, packet->payload, packet->payload_len);
}