diff --git a/routes/dmr.py b/routes/dmr.py
index d993614..e8d91fa 100644
--- a/routes/dmr.py
+++ b/routes/dmr.py
@@ -20,6 +20,7 @@ from utils.logging import get_logger
 from utils.sse import format_sse
 from utils.event_pipeline import process_event
 from utils.process import register_process, unregister_process
+from utils.validation import validate_frequency, validate_gain, validate_device_index
 from utils.constants import (
     SSE_QUEUE_TIMEOUT,
     SSE_KEEPALIVE_INTERVAL,
@@ -56,12 +57,12 @@ _DSD_PROTOCOL_FLAGS = {
 
 # dsd-fme uses different flag names
 _DSD_FME_PROTOCOL_FLAGS = {
-    'auto': ['-ft'],
-    'dmr': ['-fs'],
-    'p25': ['-f1'],
-    'nxdn': ['-fi'],
-    'dstar': [],
-    'provoice': ['-fp'],
+    'auto': [],
+    'dmr': ['-fd'],
+    'p25': ['-fp'],
+    'nxdn': ['-fn'],
+    'dstar': ['-fi'],
+    'provoice': ['-fv'],
 }
 
 # ============================================
@@ -321,16 +322,13 @@ def start_dmr() -> Response:
     data = request.json or {}
 
     try:
-        frequency = float(data.get('frequency', 462.5625))
-        gain = int(data.get('gain', 40))
-        device = int(data.get('device', 0))
+        frequency = validate_frequency(data.get('frequency', 462.5625))
+        gain = int(validate_gain(data.get('gain', 40)))
+        device = validate_device_index(data.get('device', 0))
         protocol = str(data.get('protocol', 'auto')).lower()
     except (ValueError, TypeError) as e:
         return jsonify({'status': 'error', 'message': f'Invalid parameter: {e}'}), 400
 
-    if frequency <= 0:
-        return jsonify({'status': 'error', 'message': 'Frequency must be positive'}), 400
-
     if protocol not in VALID_PROTOCOLS:
         return jsonify({'status': 'error', 'message': f'Invalid protocol. Use: {", ".join(VALID_PROTOCOLS)}'}), 400
 
@@ -402,6 +400,21 @@ def start_dmr() -> Response:
             if dmr_dsd_process.stderr:
                 dsd_err = dmr_dsd_process.stderr.read().decode('utf-8', errors='replace')[:500]
             logger.error(f"DSD pipeline died: rtl_fm rc={rtl_rc} err={rtl_err!r}, dsd rc={dsd_rc} err={dsd_err!r}")
+            # Terminate surviving process and unregister both
+            for proc in [dmr_dsd_process, dmr_rtl_process]:
+                if proc and proc.poll() is None:
+                    try:
+                        proc.terminate()
+                        proc.wait(timeout=2)
+                    except Exception:
+                        try:
+                            proc.kill()
+                        except Exception:
+                            pass
+                if proc:
+                    unregister_process(proc)
+            dmr_rtl_process = None
+            dmr_dsd_process = None
             if dmr_active_device is not None:
                 app_module.release_sdr_device(dmr_active_device)
                 dmr_active_device = None
diff --git a/tests/test_dmr.py b/tests/test_dmr.py
index 953d661..8f6e4e7 100644
--- a/tests/test_dmr.py
+++ b/tests/test_dmr.py
@@ -2,7 +2,7 @@
 
 from unittest.mock import patch, MagicMock
 import pytest
-from routes.dmr import parse_dsd_output
+from routes.dmr import parse_dsd_output, _DSD_PROTOCOL_FLAGS, _DSD_FME_PROTOCOL_FLAGS
 
 
 # ============================================
@@ -98,6 +98,21 @@ def test_parse_unrecognized():
     assert result['text'] == 'some random text'
 
 
+def test_dsd_fme_protocol_flags_match_classic():
+    """dsd-fme flags must match classic DSD flags (same fork, same CLI)."""
+    assert _DSD_FME_PROTOCOL_FLAGS == _DSD_PROTOCOL_FLAGS
+
+
+def test_dsd_protocol_flags_known_values():
+    """Protocol flags should map to the correct DSD -f flags."""
+    assert _DSD_PROTOCOL_FLAGS['dmr'] == ['-fd']
+    assert _DSD_PROTOCOL_FLAGS['p25'] == ['-fp']
+    assert _DSD_PROTOCOL_FLAGS['nxdn'] == ['-fn']
+    assert _DSD_PROTOCOL_FLAGS['dstar'] == ['-fi']
+    assert _DSD_PROTOCOL_FLAGS['provoice'] == ['-fv']
+    assert _DSD_PROTOCOL_FLAGS['auto'] == []
+
+
 # ============================================
 # Endpoint tests
 # ============================================