apps: check for sample rate availability

apps/osmocom_fft

@@ -97,6 +97,12 @@ class app_top_block(stdgui2.std_top_block, pubsub):
 
         self.src = osmosdr.source_c(options.args)
 
+        try:
+            self.src.get_sample_rates().start()
+        except RuntimeError:
+            print "Source has no sample rates (wrong device arguments?)."
+            sys.exit(1)
+
         # Set the antenna
         if(options.antenna):
             self.src.set_antenna(options.antenna)

apps/osmocom_siggen_base.py

@@ -159,6 +159,12 @@ class top_block(gr.top_block, pubsub):
     def _setup_osmosdr(self, options):
         self._sink = osmosdr.sink_c(options.args)
 
+        try:
+            self._sink.get_sample_rates().start()
+        except RuntimeError:
+            print "Sink has no sample rates (wrong device arguments?)."
+            sys.exit(1)
+
         if options.samp_rate is None:
             options.samp_rate = self._sink.get_sample_rates().start()
 

apps/osmocom_spectrum_sense

@@ -149,6 +149,12 @@ class my_top_block(gr.top_block):
         # build graph
         self.u = osmosdr.source_c(options.args)
 
+        try:
+            self.u.get_sample_rates().start()
+        except RuntimeError:
+            print "Source has no sample rates (wrong device arguments?)."
+            sys.exit(1)
+
         # Set the antenna
         if(options.antenna):
             self.u.set_antenna(options.antenna, 0)