Adding a pick bitrate calculation for new tx/rx modulators with arbitrary samples per second to allow and real valued bitrate.

3 files changed, 84 insertions, 15 deletions

diff --git a/gnuradio-examples/python/digital/pick_bitrate2.py b/gnuradio-examples/python/digital/pick_bitrate2.py
new file mode 100644
index 000000000..c0188dc3c
--- /dev/null
+++ b/gnuradio-examples/python/digital/pick_bitrate2.py
@@ -0,0 +1,64 @@
+from gnuradio import eng_notation
+
+def pick_rx_bitrate(bitrate, bits_per_symbol,
+                    converter_rate, possible_decims):
+    """
+    Given the 4 input parameters, return at configuration that matches
+
+    @param bitrate: desired bitrate or None
+    @type bitrate: number or None
+    @param bits_per_symbol: E.g., BPSK -> 1, QPSK -> 2, 8-PSK -> 3
+    @type bits_per_symbol: integer >= 1
+    @param converter_rate: converter sample rate in Hz
+    @type converter_rate: number
+    @param possible_decims: a list of possible rates
+    @type possible_decims: a list of integers
+
+    @returns tuple (bitrate, samples_per_symbol, decim_rate)
+    """
+
+    rates = list(possible_decims)
+    rates.sort()
+
+    for i in xrange(len(rates)):
+        if((converter_rate / float(bits_per_symbol) / rates[i]) >= 2*bitrate):
+            decim = rates[i]
+        else:
+            break
+
+    sps = converter_rate / float(bits_per_symbol) / decim / bitrate
+    br = converter_rate / float(bits_per_symbol) / decim / sps
+
+    return (br, sps, int(decim))
+
+
+def pick_tx_bitrate(bitrate, bits_per_symbol,
+                    converter_rate, possible_interps):
+    """
+    Given the 4 input parameters, return at configuration that matches
+
+    @param bitrate: desired bitrate or None
+    @type bitrate: number or None
+    @param bits_per_symbol: E.g., BPSK -> 1, QPSK -> 2, 8-PSK -> 3
+    @type bits_per_symbol: integer >= 1
+    @param converter_rate: converter sample rate in Hz
+    @type converter_rate: number
+    @param possible_interps: a list of possible rates
+    @type possible_interps: a list of integers
+
+    @returns tuple (bitrate, samples_per_symbol, interp_rate)
+    """
+
+    rates = list(possible_interps)
+    rates.sort()
+
+    for i in xrange(len(rates)):
+        if((converter_rate / float(bits_per_symbol) / rates[i]) >= 2*bitrate):
+            interp = rates[i]
+        else:
+            break
+
+    sps = converter_rate / float(bits_per_symbol) / interp / bitrate
+    br = converter_rate / float(bits_per_symbol) / interp / sps
+
+    return (br, sps, int(interp))
diff --git a/gnuradio-examples/python/digital/usrp_receive_path.py b/gnuradio-examples/python/digital/usrp_receive_path.py
index 517825cc1..2d3d648a0 100644
--- a/gnuradio-examples/python/digital/usrp_receive_path.py
+++ b/gnuradio-examples/python/digital/usrp_receive_path.py
@@ -22,7 +22,7 @@
 from gnuradio import gr
 from gnuradio import usrp_options
 import receive_path
-from pick_bitrate import pick_rx_bitrate
+from pick_bitrate2 import pick_rx_bitrate
 from gnuradio import eng_notation
 
 def add_freq_option(parser):
@@ -81,16 +81,19 @@ class usrp_receive_path(gr.hier_block2):
         self.rs_rate = options.bitrate
         if options.verbose:
             print 'USRP Source:', self.u
+
+            
+        #(self._bitrate, self._samples_per_symbol, self._decim) = \
+        #                pick_rx_bitrate(options.bitrate, self._demod_class.bits_per_symbol(), \
+        #                                options.samples_per_symbol, options.decim, adc_rate,  \
+        #                                self.u.get_decim_rates())
         (self._bitrate, self._samples_per_symbol, self._decim) = \
                         pick_rx_bitrate(options.bitrate, self._demod_class.bits_per_symbol(), \
-                                        options.samples_per_symbol, options.decim, adc_rate,  \
-                                        self.u.get_decim_rates())
+                                        adc_rate, self.u.get_decim_rates())
+
+        print "USRP Decimation: ", self._decim
+        print "Samples Per Symbol: ", self._samples_per_symbol
 
-        # Calculate resampler rate based on requested and actual rates
-        self.rs_rate = 1.0 /(self._bitrate / self.rs_rate)
-        
-        print "Resampling by %f to get bitrate of %ssps" % ( self.rs_rate, eng_notation.num_to_str(self._bitrate/self.rs_rate))
-        
         self.u.set_decim(self._decim)
 
         if not self.u.set_center_freq(options.rx_freq):
diff --git a/gnuradio-examples/python/digital/usrp_transmit_path.py b/gnuradio-examples/python/digital/usrp_transmit_path.py
index ee63dcd2b..4244c33f2 100644
--- a/gnuradio-examples/python/digital/usrp_transmit_path.py
+++ b/gnuradio-examples/python/digital/usrp_transmit_path.py
@@ -22,7 +22,7 @@
 from gnuradio import gr
 from gnuradio import usrp_options
 import transmit_path
-from pick_bitrate import pick_tx_bitrate
+from pick_bitrate2 import pick_tx_bitrate
 from gnuradio import eng_notation
 
 def add_freq_option(parser):
@@ -84,15 +84,17 @@ class usrp_transmit_path(gr.hier_block2):
         self.rs_rate = options.bitrate    # Store requested bit rate
         if options.verbose:
             print 'USRP Sink:', self.u
+        #(self._bitrate, self._samples_per_symbol, self._interp) = \
+        #                pick_tx_bitrate(options.bitrate, self._modulator_class.bits_per_symbol(), \
+        #                                options.samples_per_symbol, options.interp, dac_rate, \
+        #                                self.u.get_interp_rates())
         (self._bitrate, self._samples_per_symbol, self._interp) = \
                         pick_tx_bitrate(options.bitrate, self._modulator_class.bits_per_symbol(), \
-                                        options.samples_per_symbol, options.interp, dac_rate, \
-                                        self.u.get_interp_rates())
-
-        # Calculate resampler rate based on requested and actual rates
-        self.rs_rate = self._bitrate / self.rs_rate
-        print "Resampling by %f to get bitrate of %ssps" % (self.rs_rate, eng_notation.num_to_str(self._bitrate/self.rs_rate))
+                                        dac_rate, self.u.get_interp_rates())
 
+        print "USRP Interpolation: ", self._interp
+        print "Samples Per Symbol: ", self._samples_per_symbol
+        
         self.u.set_interp(self._interp)
         self.u.set_auto_tr(True)