Dorn Hetzel wrote: > On Sat, Jan 01, 2005 at 07:23:58PM -0500, Jim Van Meggelen wrote: >> [...] >> What if, for example, the TDM400 issues were a cumulative thing? If >> you had over 6dB of attenuation on the PSTN loop, coupled with >> greater than 5V potential on the neutral-ground of your elecrical >> receptacle, compounded by a cheap power supply, exascerbated by a >> Via-chipset, would you not be virtually guaranteed some strange >> behaviour? But if your PSTN was -3dB, your electrical feed derived >> from a power conditioner, your power supply manufactured by PC Power >> & Cooling, and a ServerWorks chipset-based MoBo, would your system >> always be faultless? >> > Can you recommend any favorite motherboards?
That is the million dollar question. Chipsets and MoBos seem to change so fast that I've lost confidence in my ability to make sense of it all. The Intel and ServerWorks chipsets are generally well regarded; Via chipsets are almost universally avoided for audio work. The linux-audio-dev folks seem willing to give nVidia's nForce chipsets a chance. In general, I would avoid PC-class motherboards, and go with server-class motherboards. That being said, the ultimate goal would be to find a way to build a reliable Asterisk system on *any* half-decent motherboard. Personally, I'm of the mind that power (the power supply, the AC being supplied to the system, and grounding) plays as much of a role as the motherboard does, but that is a working theory only. I wonder if clean power on a lousy MoBo might serve as well as dirty power on a quality MoBo. If one reads about power quality issues, the symptoms of dirty power sound suspiciously similar to the kinds of problems people are having with their analog Asterisk cards. I'm also wondering about the TDM400s ability to handle PSTN loops at the extreme limits. Since those TDM cards were probably developed largely in a lab environment, the telco lines would have been simulated with a channel bank or C.O. simulator. What happens when the lines fall out of certain limits? Annenuation, loop current, and longitudinal imbalance are all factors that proprietary PBXs are able to correct within fairly wide limits - but they do have limits (a Norstar, for example, tends to have trouble pulling dial tone when attenuation exceeds 7dB). Has the TDM400/FXO been similarly optimized? It must have limits; what are they? I think what we are all looking for is some empirical evidence of what conditions cause the biggest problems. Is it the TDM400 that is to blame (either hardware or drivers)? Or is it Linux? PC Hardware? Telco Lines? Electrical? Grounding? A combination of some or all of those factors? No one seems to know for certain. Where much frustration comes from is the fact that a typical PBX simply does not suffer from these troubles. We've come to expect that our telecom equipment handles these little noises for us (so much so that we're suprised to find that these are genuine engineering issues). With Asterisk, some of the responsibility for correcting those problems falls to us, the system designers. Unfortunately, a comprehensive engineering methodology for analog devices on Asterisk does not yet exist. It's all kind of hit-and-miss. Cheers, Jim. -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.296 / Virus Database: 265.6.7 - Release Date: 30/12/2004 _______________________________________________ Asterisk-Users mailing list [email protected] http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
