pifmrds at 20khz lowpass and install pifmrds

src/Makefile

@@ -107,4 +107,5 @@ install: all
 	install -m 0755 ../rpitx $(INSTALL_DIR)
 	install -m 0755 ../pift8 $(INSTALL_DIR)
 	install -m 0755 ../sendook $(INSTALL_DIR)
-	install -m 0755 ../dvbrf $(INSTALL_DIR)
+	install -m 0755 ../dvbrf $(INSTALL_DIR)
+	install -m 0755 ../pifmrds $(INSTALL_DIR)

src/pifmrds/fm_mpx.c

@@ -117,7 +117,7 @@ int fm_mpx_open(char *filename, size_t len) {
         }
     
         // Choose a cutoff frequency for the low-pass FIR filter
-        float cutoff_freq = 15700;
+        float cutoff_freq = 20000;
 		//float cutoff_freq = 3000; //For NBFM
         if(in_samplerate/2 < cutoff_freq) cutoff_freq = in_samplerate/2 * .8;