diff --git a/htdocs/lib/DemodulatorPanel.js b/htdocs/lib/DemodulatorPanel.js
index 421487c..3c91fcc 100644
--- a/htdocs/lib/DemodulatorPanel.js
+++ b/htdocs/lib/DemodulatorPanel.js
@@ -249,12 +249,17 @@ DemodulatorPanel.prototype.updateButtons = function() {
 }
 
 DemodulatorPanel.prototype.setCenterFrequency = function(center_freq) {
-    if (this.center_freq === center_freq) {
-        return;
+    var me = this;
+    if (me.centerFreqTimeout) {
+        clearTimeout(me.centerFreqTimeout);
+        me.centerFreqTimeout = false;
     }
-    this.stopDemodulator();
-    this.center_freq = center_freq;
-    this.startDemodulator();
+    this.centerFreqTimeout = setTimeout(function() {
+        me.stopDemodulator();
+        me.center_freq = center_freq;
+        me.startDemodulator();
+        me.centerFreqTimeout = false;
+    }, 50);
 };
 
 DemodulatorPanel.prototype.parseHash = function() {
diff --git a/owrx/connection.py b/owrx/connection.py
index c8cfbec..ddc6fa9 100644
--- a/owrx/connection.py
+++ b/owrx/connection.py
@@ -133,9 +133,6 @@ class OpenWebRxReceiverClient(OpenWebRxClient, SdrSourceEventClient):
         self.configSub = None
         self.connectionProperties = {}
 
-        # to be able to remember if the dsp has been started before
-        self.dspState = False
-
         try:
             ClientRegistry.getSharedInstance().addClient(self)
         except TooManyClientsException:
@@ -186,7 +183,6 @@ class OpenWebRxReceiverClient(OpenWebRxClient, SdrSourceEventClient):
             if "type" in message:
                 if message["type"] == "dspcontrol":
                     if "action" in message and message["action"] == "start":
-                        self.dspState = True
                         self.startDsp()
 
                     if "params" in message:
@@ -278,8 +274,6 @@ class OpenWebRxReceiverClient(OpenWebRxClient, SdrSourceEventClient):
         self.__sendProfiles()
 
         self.sdr.addSpectrumClient(self)
-        if self.dspState:
-            self.startDsp()
 
     def handleNoSdrsAvailable(self):
         self.write_sdr_error("No SDR Devices available")