break apart the ever-growing owrx/source.py

owrx/source/rtl_sdr.py

@@ -0,0 +1,16 @@
+from .connector import ConnectorSource
+
+
+class RtlSdrSource(ConnectorSource):
+    def getCommand(self):
+        cmd = (
+                "rtl_connector -p {port} -c {controlPort}".format(port=self.port, controlPort=self.controlPort)
+                + " -s {samp_rate} -f {tuner_freq} -g {rf_gain} -P {ppm}"
+        )
+        if "device" in self.rtlProps and self.rtlProps["device"] is not None:
+            cmd += ' -d "{device}"'
+        if self.rtlProps["iqswap"]:
+            cmd += " -i"
+        if self.rtlProps["rtltcp_compat"]:
+            cmd += " -r"
+        return cmd