I am running version .273 code in Centos running on an Intel Atom D510,(which reports "Total of 4 processors activated (13333.62 BogoMIPS)") and am trying to use a radio receiver that does not have built in CTCSS decode. I am getting audio directly from the discriminator and the "radio tune rxnoise" and "radio tune rxtone" setting is successful but it acts like I am set for carrier squelch even though I think I am setup for dsp CTCSS squelch in usbradio.conf. Here are my settings from usbradio.conf. What am I doing wrong? Is it not possible to decode CTCSS in software and have it only allow signals in that have the correct tone? Chuck [usb27468] hdwtype=0 rxboost=0 txboost=0 rxctcssrelax=1 txctcssdefault=131.8 rxctcssfreqs=131.8 txctcssfreqs=131.8 rxctcssoverride=1 carrierfrom=usbinvert ; Options - no,usb,usbinvert,dsp,vox ; no - no carrier detection at all ; usb - via USB radio adapter COR connection ; usbinvert - same as above but inverted polarity. ; dsp - from RX noise using dsp methods ; vox - voice activated via RX audio ctcssfrom=dsp ; Options = no,usb,dsp ; no - CTCSS decoding, system will be carrier squelch ; usb - CTCSS decoding using input from USB adapter ; usbinvert - same as above but inverted polarity. ; dsp - CTCSS decoding using RX audio in DSP. ; rxdemod option must be set to flat for this to work. rxdemod=flat ; Options = no, flat, speaker ; no - RX audio input not used ; flat - source is un-filtered discriminator signal ; speaker - source is filtered, de-emphasized audio txprelim=no txlimonly=no txtoctype=no txmixa=voice txmixb=voice invertptt=0 duplex=1 rxondelay=0 rxnoisefiltype=0 eeprom=0