diff --git a/routes/morse.py b/routes/morse.py
index 0e953b0..8936f3c 100644
--- a/routes/morse.py
+++ b/routes/morse.py
@@ -544,6 +544,7 @@ def start_morse() -> Response:
             stop_event = threading.Event()
             control_queue = queue.Queue(maxsize=16)
             pcm_ready_event = threading.Event()
+            stream_ready_event = threading.Event()
             attempt_stderr_lines: list[str] = []
 
             def monitor_stderr(
@@ -598,6 +599,7 @@ def start_morse() -> Response:
                         'decoder_config': runtime_config,
                         'control_queue': control_queue,
                         'pcm_ready_event': pcm_ready_event,
+                        'stream_ready_event': stream_ready_event,
                     },
                     daemon=True,
                     name='morse-decoder',
@@ -617,6 +619,7 @@ def start_morse() -> Response:
                         'decoder_config': runtime_config,
                         'control_queue': control_queue,
                         'pcm_ready_event': pcm_ready_event,
+                        'stream_ready_event': stream_ready_event,
                         'strip_text_chunks': False,
                     },
                     daemon=True,
@@ -642,6 +645,8 @@ def start_morse() -> Response:
                     startup_error = 'No PCM samples received within startup timeout'
                 if attempt_stderr_lines:
                     startup_error = f'{startup_error}; stderr: {attempt_stderr_lines[-1]}'
+                if stream_ready_event.is_set():
+                    startup_error = f'{startup_error}; stream=alive'
 
                 is_last_attempt = attempt_index == len(command_attempts)
                 if (
diff --git a/utils/morse.py b/utils/morse.py
index 915b953..58c03dc 100644
--- a/utils/morse.py
+++ b/utils/morse.py
@@ -11,7 +11,9 @@ from __future__ import annotations
 
 import contextlib
 import math
+import os
 import queue
+import select
 import struct
 import threading
 import time
@@ -763,6 +765,7 @@ def morse_decoder_thread(
     decoder_config: dict[str, Any] | None = None,
     control_queue: queue.Queue | None = None,
     pcm_ready_event: threading.Event | None = None,
+    stream_ready_event: threading.Event | None = None,
     strip_text_chunks: bool = False,
 ) -> None:
     """Decode Morse from live PCM stream and push events to *output_queue*."""
@@ -800,16 +803,26 @@ def morse_decoder_thread(
     first_pcm_logged = False
     reader_done = threading.Event()
     reader_thread: threading.Thread | None = None
+    first_raw_logged = False
 
     raw_queue: queue.Queue[bytes] = queue.Queue(maxsize=96)
 
     try:
         def _reader_loop() -> None:
             """Blocking PCM reader isolated from decode/control loop."""
+            nonlocal first_raw_logged
             try:
+                fd = None
+                with contextlib.suppress(Exception):
+                    fd = rtl_stdout.fileno()
                 while not stop_event.is_set():
                     try:
-                        if hasattr(rtl_stdout, 'read1'):
+                        if fd is not None:
+                            ready, _, _ = select.select([fd], [], [], 0.20)
+                            if not ready:
+                                continue
+                            data = os.read(fd, CHUNK)
+                        elif hasattr(rtl_stdout, 'read1'):
                             data = rtl_stdout.read1(CHUNK)
                         else:
                             data = rtl_stdout.read(CHUNK)
@@ -827,6 +840,16 @@ def morse_decoder_thread(
                     if not data:
                         break
 
+                    if not first_raw_logged:
+                        first_raw_logged = True
+                        if stream_ready_event is not None:
+                            stream_ready_event.set()
+                        with contextlib.suppress(queue.Full):
+                            output_queue.put_nowait({
+                                'type': 'info',
+                                'text': f'[pcm] first raw chunk: {len(data)} bytes',
+                            })
+
                     if strip_text_chunks and _is_probably_rtl_log_text(data):
                         try:
                             text = data.decode('utf-8', errors='replace')
@@ -1026,6 +1049,7 @@ def morse_iq_decoder_thread(
     decoder_config: dict[str, Any] | None = None,
     control_queue: queue.Queue | None = None,
     pcm_ready_event: threading.Event | None = None,
+    stream_ready_event: threading.Event | None = None,
 ) -> None:
     """Decode Morse from raw IQ (cu8) by in-process USB demodulation."""
     import logging
@@ -1062,15 +1086,25 @@ def morse_iq_decoder_thread(
     first_pcm_logged = False
     reader_done = threading.Event()
     reader_thread: threading.Thread | None = None
+    first_raw_logged = False
 
     raw_queue: queue.Queue[bytes] = queue.Queue(maxsize=96)
 
     try:
         def _reader_loop() -> None:
+            nonlocal first_raw_logged
             try:
+                fd = None
+                with contextlib.suppress(Exception):
+                    fd = iq_stdout.fileno()
                 while not stop_event.is_set():
                     try:
-                        if hasattr(iq_stdout, 'read1'):
+                        if fd is not None:
+                            ready, _, _ = select.select([fd], [], [], 0.20)
+                            if not ready:
+                                continue
+                            data = os.read(fd, CHUNK)
+                        elif hasattr(iq_stdout, 'read1'):
                             data = iq_stdout.read1(CHUNK)
                         else:
                             data = iq_stdout.read(CHUNK)
@@ -1087,6 +1121,16 @@ def morse_iq_decoder_thread(
                     if not data:
                         break
 
+                    if not first_raw_logged:
+                        first_raw_logged = True
+                        if stream_ready_event is not None:
+                            stream_ready_event.set()
+                        with contextlib.suppress(queue.Full):
+                            output_queue.put_nowait({
+                                'type': 'info',
+                                'text': f'[iq] first raw chunk: {len(data)} bytes',
+                            })
+
                     try:
                         raw_queue.put(data, timeout=0.2)
                     except queue.Full: