From mboxrd@z Thu Jan 1 00:00:00 1970 From: ariel mastracchio Subject: Re: Soundmodem Not Decoding Real Packets Date: Sat, 2 Jul 2005 12:03:35 -0700 (PDT) Message-ID: <20050702190335.12000.qmail@web51004.mail.yahoo.com> References: Mime-Version: 1.0 Content-Transfer-Encoding: 7BIT Return-path: In-Reply-To: Sender: linux-hams-owner@vger.kernel.org List-Id: Content-Type: text/plain; charset="us-ascii" To: Jonathan Lassoff , linux-hams@vger.kernel.org Hello, The motherboard i have with onboard sound card didn't work (it transmit ok, but dont decode packets, the scope graph show a very small bandwidth with blank noise) , i have to buy a sound blaste PCI, and work fine!! hugs lu9aum --- Jonathan Lassoff wrote: > Dave Platt radagast.org> writes: > > Hmmm. > > > > Which audio drivers are you using - OSS, or ALSA? > > I've tried both. I'm using the i810_audio module > with the AC97 codec for an > on-board sound device on a laptop. > > > I've seen some rather bizarre things with some > combinations of card, > > driver, and software setting. In particular, > problems can occur if: > > > > [1] The card itself is only capable of supporting > a small selection of > > sampling rates (many AC97 codes seem to want > to run at 48000 > > samples/second), and > > > > [2] You set up the sound modem to use the > "natural" sampling rate for > > the modulation in question (e.g. 9600 > samples/second for 1200-baud > > packet), and > > I cannot seem to find where this is set. Are the > specifications for the config > file somewhere? > > > [3] The soundmodem is configured to use /dev/dsp, > and > > > > [4] You're using an ALSA driver with OSS > emulation. > > > > What seems to happen is that the OSS emulation > layer quite politely > > lies to the soundmodem, says "Sure, 9600 > samples/second is supported", > > and then tells the ALSA PCM layer to do > sample-rate conversion in > > software. The ALSA rate converter has some > problems, and it ends up > > introducing noise into the received audio signal > occasionally (usually > > on internal buffer boundaries, I believe). The > noise is sufficient to > > mess up the audio reception. > > > > The solution to this involves disabling the sample > rate conversion > > process. I _think_ (but am not sure) that the > best way to do this is > > to tell the soundmodem to use the ALSA API > directly, rather than using > > the OSS emulation via /dev/dsp - recent versions > of the soundmodem can > > do this, and are smart enough to use a sampling > rate that the audio > > chip supports directly with no conversion being > required. > > Well, from some of the things you have pointed out, > I might suspect an audio > driver issue, but I'm not sure if the ALSA driver is > using OSS emulation with > the older i810_audio driver. > > - > To unsubscribe from this list: send the line > "unsubscribe linux-hams" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at > http://vger.kernel.org/majordomo-info.html > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com