diff --git a/include/serial_AT.hpp b/include/serial_AT.hpp
index ddf8699..0b3fc48 100644
--- a/include/serial_AT.hpp
+++ b/include/serial_AT.hpp
@@ -5,6 +5,17 @@
 // 全局 IMEI（读取成功后写入）
 extern std::string IMEI;
 
+struct RadioInfo
+{
+    int rsrp = -999;    // dBm
+    int rsrq = -999;    // dB
+    float sinr = -999;  // dB
+    std::string rat;    // LTE / NR5G / etc.
+    std::string band;
+};
+
+extern RadioInfo g_radio_info;
+
 // 初始化 AT 串口（启动线程）
 void init_serial_at(const std::string& device, int baudrate);
 
diff --git a/src/serial_AT.cpp b/src/serial_AT.cpp
index 470998c..a58b721 100644
--- a/src/serial_AT.cpp
+++ b/src/serial_AT.cpp
@@ -17,6 +17,9 @@
 std::string IMEI;
 std::mutex imei_mutex;
 
+RadioInfo g_radio_info;
+static std::mutex radio_mutex;
+
 // ================== 运行控制 ==================
 static std::atomic<bool> serial_at_running{false};
 
@@ -105,8 +108,13 @@ void stop_http_server()
     http_server.reset();
 }
 
-// 只保留一个任务：AT+GSN
-static std::vector<AtTask> at_tasks = {{"AT+GSN", 3, 0, {}}};
+// IMEI 需要无限重试
+// 信号 AT 命令周期查询（5 秒一次）
+// max_retries = -1 → 永不删除
+static std::vector<AtTask> at_tasks = {
+    {"AT+GSN", -1, 0, {}},                  // 直到成功为止
+    {"AT+QENG=\"servingcell\"", -1, 0, {}}  // RSRP/RSRQ/SINR 查询（周期）
+};
 
 // ================== 发送线程 ==================
 static void serial_at_send_loop()
@@ -130,12 +138,16 @@ static void serial_at_send_loop()
             {
                 auto& task = *it;
 
-                if (task.sent_count >= task.max_retries)
+                // ============================
+                // FIX: max_retries = -1 → 无限发送
+                // ============================
+                if (task.max_retries >= 0 && task.sent_count >= task.max_retries)
                 {
                     it = at_tasks.erase(it);
                     continue;
                 }
 
+                // 5 秒一次发送
                 if (task.last_sent.time_since_epoch().count() == 0 ||
                     std::chrono::duration_cast<std::chrono::seconds>(now - task.last_sent).count() >= 5)
                 {
@@ -176,10 +188,63 @@ static void handle_serial_at_data(const std::string& data)
 
             LOG_INFO("[serial_at] IMEI = " + line);
 
-            std::lock_guard<std::mutex> lock(at_tasks_mutex);
-            at_tasks.clear();
+            {
+                std::lock_guard<std::mutex> lock(at_tasks_mutex);
+
+                // 保留非 IMEI 的任务
+                at_tasks.erase(
+                    std::remove_if(at_tasks.begin(), at_tasks.end(), [](const AtTask& t) { return t.cmd == "AT+GSN"; }),
+                    at_tasks.end());
+            }
+
             return;
         }
+
+        // =======================
+        // QENG="servingcell" 解析
+        // =======================
+        if (line.rfind("+QENG:", 0) == 0 || line.find("servingcell") != std::string::npos)
+        {
+            std::vector<std::string> tokens;
+            std::string tmp;
+            std::stringstream ss(line);
+
+            while (std::getline(ss, tmp, ','))
+            {
+                // 去除双引号和空白
+                tmp.erase(std::remove(tmp.begin(), tmp.end(), '"'), tmp.end());
+                tmp.erase(0, tmp.find_first_not_of(" \t"));
+                tmp.erase(tmp.find_last_not_of(" \t") + 1);
+                tokens.push_back(tmp);
+            }
+
+            // LTE 格式固定至少 15~17 字段
+            if (tokens.size() >= 15)
+            {
+                // 对号入座
+                int pci = std::stoi(tokens[6]);    // 物理小区编号
+                int band = std::stoi(tokens[8]);   // LTE band
+                int rsrp = std::stoi(tokens[11]);  // dBm
+                int rsrq = std::stoi(tokens[12]);  // dB
+                int sinr = std::stoi(tokens[14]);  // dB
+
+                {
+                    std::lock_guard<std::mutex> lk(radio_mutex);
+                    g_radio_info.pci = pci;
+                    g_radio_info.band = band;
+                    g_radio_info.rsrp = rsrp;
+                    g_radio_info.rsrq = rsrq;
+                    g_radio_info.sinr = sinr;
+                    g_radio_info.raw = line;  // 保留原始字符串用于调试
+                }
+
+                LOG_INFO("[serial_at] QENG parsed: RSRP=" + std::to_string(rsrp) + " RSRQ=" + std::to_string(rsrq) +
+                         " SINR=" + std::to_string(sinr) + " PCI=" + std::to_string(pci) +
+                         " BAND=" + std::to_string(band));
+
+                continue;
+            }
+        }
     }
 }