From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jochen Schaeuble Subject: Re: problems with soundmodem (userspace) Date: Tue, 08 Jun 2004 22:26:43 +0200 Sender: linux-hams-owner@vger.kernel.org Message-ID: <40C62103.8010607@psionic.de> References: <20040607203614.30352.qmail@radagast.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20040607203614.30352.qmail@radagast.org> List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: linux-hams@vger.kernel.org Hi, thanks for your reply. I've found the problem. As you suggested it had something to do with the audio level. The soundcard-interface I use here seems to have some problems. If I directly connect the audio output of the soundcard to the data input of the TX everything works. Thanks for your help. vy 73 de Jochen DG1PSI Dave Platt wrote: > Jochen Schaeuble wrote: > >>Hi, >>I have several problems setting up the userspace version of soundmodem >>with 9k6. Everything works perfect if I only send a small set of >>characters (like c or m) - but sometimes a bit slow. If I enter a larger >>amount of text (like a message) the connection is lost after about 10 >>minutes of retries. Any hints what I'm doing wrong? I use a Yaesu FT-817 >>with Debian testing (Kernel 2.4.22, ALSA). The parameters of soundmodem >>are as follows: >> >>txdelay="150" slottime="30" ppersist="30" fulldup="0" txtail="25" >> >>As terminal I use xcall. >> >>Is it better to use the kernelspace driver? > > > From what I've seen, problems with the user-mode soundmodem driver > can fall into the following categories: > > - Incorrect audio levels. A receiver whose audio output is too > "hot" can overdrive a PC's sound card input, clipping the > waveforms and distorting the signal. Similarly, a PC whose > audio output level is set too high can overdrive the rig's > microphone or accessory audio input, clipping the signal or > overdeviating. > > The 9k6 FSK modulation is, I understand, quite "touchy" in > terms of the transmit audio level. Since you're driving the > modulator directly, too high an audio output level can > easily over-deviate your signal, and you might drive the > signal out past the receiving radio's discriminator lock > range. > > See if you can find someone in your area who has a > deviation/modulation meter, and see whether you're pushing the > transmit deviation too hard. > > - Incorrect setting of the radio. For 9k6 FSK, you can't use > the mic and speaker jacks. You must use an audio interface > which bypasses the transmit equalization circuitry, and which > gives you access to the receiver's discriminator output without > re-equalization. Some radios with auxiliary audio jacks have > a menu setting e.g. "1200" or "9600" - if the FT-817 has such > a menu, make sure you've selected 9600. > > - Sound-card resampling problems. Many modern PCs use sound > interfaces based on the AC97 codecs, which have only a couple > of hardware sampling rates. The soundmodem driver may be expecting > to use a different sampling rate. If the soundmodem sample rate > and the codec sample rates don't overlap, then somebody has to > re-sample the audio data - some chipsets do this in hardware, while > others have no such ability and require the CPU and drivers to do > the resampling. ALSA's OSS-compatibility driver will try to do > resampling, but some reports on this group seem to indicate that the > resampling code has bugs in it and can result in bad samples being > transmitted or received. > > Also, packet transmissions in general and (I think) 9k6 in particular > are often quite sensitive to RF signal quality. In particular, > multipath reflections can result in enough inter-symbol interference > to render the signal unreadable. Use of directional beam antennas, > mounted high up in the clear, may clean up the signal enough to make > the channel usable. > > Another thing to check is to make sure that your radio isn't set > in a power-saving mode, which leaves the receiver turned off much > of the time. These modes play merry hell with packet, as the SYNC > bursts are often lost. > > My guess is that the kernel soundmodem driver is probably not going > to be the cure for your problem... the fault lies elsewhere.