diff --git a/config_webrx.py b/config_webrx.py
index a4f63ef..a9c25d1 100644
--- a/config_webrx.py
+++ b/config_webrx.py
@@ -103,9 +103,12 @@ Note: if you experience audio underruns while CPU usage is 100%, you can:
 
 # You can use other SDR hardware as well, by giving your own command that outputs the I/Q samples... Some examples of configuration are available here (default is RTL-SDR):
 
+# valid: "rtl_sdr", "sdrplay", "hackrf"
+rtl_type = "rtl_sdr"
+
 # >> RTL-SDR via rtl_sdr
-start_rtl_command="rtl_sdr -s {samp_rate} -f {center_freq} -p {ppm} -g {rf_gain} -".format(rf_gain=rf_gain, center_freq=center_freq, samp_rate=samp_rate, ppm=ppm)
-format_conversion="csdr convert_u8_f"
+#start_rtl_command="rtl_sdr -s {samp_rate} -f {center_freq} -p {ppm} -g {rf_gain} -".format(rf_gain=rf_gain, center_freq=center_freq, samp_rate=samp_rate, ppm=ppm)
+#format_conversion="csdr convert_u8_f"
 
 #lna_gain=8
 #rf_amp=1
diff --git a/csdr.py b/csdr.py
index b9fc6a0..616cb25 100755
--- a/csdr.py
+++ b/csdr.py
@@ -45,7 +45,6 @@ class dsp:
         self.fft_compression = "none"
         self.demodulator = "nfm"
         self.name = "csdr"
-        self.format_conversion = "csdr convert_u8_f"
         self.base_bufsize = 512
         self.nc_port = 4951
         self.csdr_dynamic_bufsize = False
@@ -67,7 +66,6 @@ class dsp:
         any_chain_base="nc -v 127.0.0.1 {nc_port} | "
         if self.csdr_dynamic_bufsize: any_chain_base+="csdr setbuf {start_bufsize} | "
         if self.csdr_through: any_chain_base+="csdr through | "
-        any_chain_base+=self.format_conversion+(" | " if  self.format_conversion!="" else "") ##"csdr flowcontrol {flowcontrol} auto 1.5 10 | "
         if which == "fft":
             fft_chain_base = any_chain_base+"csdr fft_cc {fft_size} {fft_block_size} | " + \
                 ("csdr logpower_cf -70 | " if self.fft_averages == 0 else "csdr logaveragepower_cf -70 {fft_size} {fft_averages} | ") + \
@@ -255,9 +253,6 @@ class dsp:
         if self.fft_averages == 0: return self.samp_rate/self.fft_fps
         else: return self.samp_rate/self.fft_fps/self.fft_averages
 
-    def set_format_conversion(self,format_conversion):
-        self.format_conversion=format_conversion
-
     def set_offset_freq(self,offset_freq):
         self.offset_freq=offset_freq
         if self.running:
diff --git a/owrx/config.py b/owrx/config.py
index ccf1161..89adf98 100644
--- a/owrx/config.py
+++ b/owrx/config.py
@@ -29,12 +29,18 @@ class PropertyManager(object):
 
     def __init__(self, properties = None):
         self.properties = {}
+        self.callbacks = []
         if properties is not None:
             for (name, prop) in properties.items():
                 self.add(name, prop)
 
     def add(self, name, prop):
         self.properties[name] = prop
+        def fireCallbacks(value):
+            for c in self.callbacks:
+                c(name, value)
+        prop.wire(fireCallbacks)
+        return self
 
     def __getitem__(self, name):
         return self.getPropertyValue(name)
@@ -50,6 +56,10 @@ class PropertyManager(object):
     def getPropertyValue(self, name):
         return self.getProperty(name).getValue()
 
+    def wire(self, callback):
+        self.callbacks.append(callback)
+        return self
+
 class RequirementMissingException(Exception):
     pass
 
@@ -58,7 +68,7 @@ class FeatureDetector(object):
         "core": [ "csdr", "nmux" ],
         "rtl_sdr": [ "rtl_sdr" ],
         "sdrplay": [ "rx_tools" ],
-        "hackrf": [ "rx_tools" ]
+        "hackrf": [ "hackrf_transfer" ]
     }
 
     def is_available(self, feature):
@@ -88,3 +98,8 @@ class FeatureDetector(object):
 
     def has_rx_tools(self):
         return os.system("rx_sdr --help 2> /dev/null") != 32512
+
+    def has_hackrf_transfer(self):
+        # TODO i don't have a hackrf, so somebody doublecheck this.
+        # TODO also check if it has the stdout feature
+        return os.system("hackrf_transfer --help 2> /dev/null") != 32512
diff --git a/owrx/controllers.py b/owrx/controllers.py
index 9bb0987..8cccd90 100644
--- a/owrx/controllers.py
+++ b/owrx/controllers.py
@@ -74,14 +74,14 @@ class WebSocketMessageHandler(object):
         self.client = None
 
     def handleTextMessage(self, conn, message):
+        pm = PropertyManager.getSharedInstance()
+
         if (message[:16] == "SERVER DE CLIENT"):
             # maybe put some more info in there? nothing to store yet.
             self.handshake = "completed"
 
             self.client = OpenWebRxClient(conn)
 
-            pm = PropertyManager.getSharedInstance()
-
             config_keys = ["waterfall_colors", "waterfall_min_level", "waterfall_max_level",
                            "waterfall_auto_level_margin", "shown_center_freq", "samp_rate", "fft_size", "fft_fps",
                            "audio_compression", "fft_compression", "max_clients", "start_mod",
@@ -117,6 +117,13 @@ class WebSocketMessageHandler(object):
 
                 if "action" in message and message["action"] == "start":
                     self.dsp.start()
+
+            if message["type"] == "config":
+                for key, value in message["params"].items():
+                    # only the keys in the protected property manager can be overridden from the web
+                    protected = pm.collect("samp_rate")
+                    protected[key] = value
+
         except json.JSONDecodeError:
             print("message is not json: {0}".format(message))
 
diff --git a/owrx/source.py b/owrx/source.py
index 9d5265a..3de6218 100644
--- a/owrx/source.py
+++ b/owrx/source.py
@@ -1,12 +1,54 @@
 import subprocess
-from owrx.config import PropertyManager
+from owrx.config import PropertyManager, FeatureDetector
 import threading
 import csdr
 import time
 
 class RtlNmuxSource(threading.Thread):
     def run(self):
-        props = PropertyManager.getSharedInstance().collect("samp_rate", "nmux_memory", "start_rtl_command", "iq_server_port")
+        props = PropertyManager.getSharedInstance().collect(
+            "rtl_type", "samp_rate", "nmux_memory", "iq_server_port", "center_freq", "ppm",
+            "rf_gain", "lna_gain", "rf_amp"
+        )
+
+        def restart(name, value):
+            print("would now restart rtl source due to property change: {0} changed to {1}".format(name, value))
+            # TODO not sure how to implement an actual restart... help
+        props.wire(restart)
+
+        featureDetector = FeatureDetector()
+        if not featureDetector.is_available(props["rtl_type"]):
+            print("The RTL source type {0} is not available. please check requirements.".format(props["rtl_type"]))
+            return
+
+        types = {
+            "rtl_sdr": {
+                "command": "rtl_sdr -s {samp_rate} -f {center_freq} -p {ppm} -g {rf_gain} -",
+                "format_conversion": "csdr convert_u8_f",
+            },
+            "hackrf": {
+                "command": "hackrf_transfer -s {samp_rate} -f {center_freq} -g {rf_gain} -l{lna_gain} -a{rf_amp} -r-",
+                "format_conversion": "csdr convert_s8_f"
+            },
+            "sdrplay": {
+                "command": "rx_sdr -F CF32 -s {samp_rate} -f {center_freq} -p {ppm} -g {rf_gain} -",
+                "format_conversion": None
+            }
+        }
+
+        params = types[props["rtl_type"]]
+
+        start_sdr_command = params["command"].format(
+            samp_rate = props["samp_rate"],
+            center_freq = props["center_freq"],
+            ppm = props["ppm"],
+            rf_gain = props["rf_gain"],
+            lna_gain = props["lna_gain"],
+            rf_amp = props["rf_amp"]
+        )
+
+        if params["format_conversion"] is not None:
+            start_sdr_command += " | " + params["format_conversion"]
 
         nmux_bufcnt = nmux_bufsize = 0
         while nmux_bufsize < props["samp_rate"]/4: nmux_bufsize += 4096
@@ -15,7 +57,7 @@ class RtlNmuxSource(threading.Thread):
             print("[RtlNmuxSource] Error: nmux_bufsize or nmux_bufcnt is zero. These depend on nmux_memory and samp_rate options in config_webrx.py")
             return
         print("[RtlNmuxSource] nmux_bufsize = %d, nmux_bufcnt = %d" % (nmux_bufsize, nmux_bufcnt))
-        cmd = props["start_rtl_command"] + "| nmux --bufsize %d --bufcnt %d --port %d --address 127.0.0.1" % (nmux_bufsize, nmux_bufcnt, props["iq_server_port"])
+        cmd = start_sdr_command + " | nmux --bufsize %d --bufcnt %d --port %d --address 127.0.0.1" % (nmux_bufsize, nmux_bufcnt, props["iq_server_port"])
         self.process = subprocess.Popen(cmd, shell=True)
         print("[RtlNmuxSource] Started rtl source: " + cmd)
         self.process.wait()
@@ -37,7 +79,7 @@ class SpectrumThread(threading.Thread):
 
     def run(self):
         props = PropertyManager.getSharedInstance().collect(
-            "samp_rate", "fft_size", "fft_fps", "fft_voverlap_factor", "fft_compression", "format_conversion",
+            "samp_rate", "fft_size", "fft_fps", "fft_voverlap_factor", "fft_compression",
             "csdr_dynamic_bufsize", "csdr_print_bufsizes", "csdr_through", "iq_server_port"
         )
 
@@ -54,7 +96,6 @@ class SpectrumThread(threading.Thread):
         dsp.set_fft_fps(fft_fps)
         dsp.set_fft_averages(int(round(1.0 * samp_rate / fft_size / fft_fps / (1.0 - fft_voverlap_factor))) if fft_voverlap_factor>0 else 0)
         dsp.set_fft_compression(props["fft_compression"])
-        dsp.set_format_conversion(props["format_conversion"])
         dsp.csdr_dynamic_bufsize = props["csdr_dynamic_bufsize"]
         dsp.csdr_print_bufsizes = props["csdr_print_bufsizes"]
         dsp.csdr_through = props["csdr_through"]
@@ -94,7 +135,7 @@ class DspManager(object):
         self.handler = handler
 
         self.localProps = PropertyManager.getSharedInstance().collect(
-            "audio_compression", "fft_compression", "format_conversion", "digimodes_fft_size", "csdr_dynamic_bufsize",
+            "audio_compression", "fft_compression", "digimodes_fft_size", "csdr_dynamic_bufsize",
             "csdr_print_bufsizes", "csdr_through", "iq_server_port", "digimodes_enable", "samp_rate"
         )
 
@@ -102,7 +143,6 @@ class DspManager(object):
         #dsp_initialized=False
         self.localProps.getProperty("audio_compression").wire(self.dsp.set_audio_compression)
         self.localProps.getProperty("fft_compression").wire(self.dsp.set_fft_compression)
-        self.localProps.getProperty("format_conversion").wire(self.dsp.set_format_conversion)
         self.dsp.set_offset_freq(0)
         self.dsp.set_bpf(-4000,4000)
         self.localProps.getProperty("digimodes_fft_size").wire(self.dsp.set_secondary_fft_size)