diff --git a/routes/acars.py b/routes/acars.py
index b5f3827..1604b90 100644
--- a/routes/acars.py
+++ b/routes/acars.py
@@ -227,8 +227,8 @@ def start_acars() -> Response:
     json_flag = get_acarsdec_json_flag(acarsdec_path)
     cmd = [acarsdec_path]
     if json_flag == '--output':
-        # f00b4r0 fork: --output json:file:- sends JSON to stdout
-        cmd.extend(['--output', 'json:file:-'])
+        # f00b4r0 fork: --output json:file (no path = stdout)
+        cmd.extend(['--output', 'json:file'])
     elif json_flag == '-j':
         cmd.append('-j')         # JSON output (TLeconte v4+)
     else:
@@ -242,8 +242,14 @@ def start_acars() -> Response:
     if ppm and str(ppm) != '0':
         cmd.extend(['-p', str(ppm)])
 
-    # Add device and frequencies (-r takes device, remaining args are frequencies)
-    cmd.extend(['-r', str(device)])
+    # Add device and frequencies
+    # f00b4r0 uses --rtlsdr <device>, TLeconte uses -r <device>
+    if json_flag == '--output':
+        # Use 3.2 MS/s sample rate for wider bandwidth (handles NA frequency span)
+        cmd.extend(['-m', '256'])
+        cmd.extend(['--rtlsdr', str(device)])
+    else:
+        cmd.extend(['-r', str(device)])
     cmd.extend(frequencies)
 
     logger.info(f"Starting ACARS decoder: {' '.join(cmd)}")
diff --git a/templates/adsb_dashboard.html b/templates/adsb_dashboard.html
index 153cbc2..4a4b77b 100644
--- a/templates/adsb_dashboard.html
+++ b/templates/adsb_dashboard.html
@@ -2466,7 +2466,11 @@ sudo make install</code>
                     const url = useAgent
                         ? `/controller/agents/${adsbCurrentAgent}/adsb/stop`
                         : '/adsb/stop';
-                    await fetch(url, { method: 'POST' });
+                    await fetch(url, {
+                        method: 'POST',
+                        headers: { 'Content-Type': 'application/json' },
+                        body: JSON.stringify({})
+                    });
 
                     // Update agent running modes tracking
                     if (useAgent && typeof agentRunningModes !== 'undefined') {