> What is the equivalent decibel level of the RTP stream being transported > through *. This may sound like a funny question but I will try to show what > I mean by a diagram below: > > PSTN Receive level into FXO card Center point level after FXO or FXS > Gain > adjustment > > PSTN >-----Transmit in -8db >---Receive 0db > PSTN <-----Receive out -5db <---Transmit 0db > > > When you attempt to make a connection from analog line to analog line the > idea is to have both channels achieve a 0/0db level at what would be termed > the center of the SWITCH> This way the call is optimized for connectign both > legs of the call. A typical tlp (Test Level Point) for PSTN lines would be > to send -5db into the PSTN from your FXO card and expect the receive level > to be -8 or -9 db at the input of your FXO card. This is the same concept > used when dealing with channel banks the digital stream level should be > 0/0db. > > It stands to reason( at least to me:) ) that if digital levels are not 0/0 > for the codecs used for transport of voice within the digital stream then > when you convert sip/iax and send it out over an analog line you will have a > gret potential for reflected power and will experience an echo issue. > > Does any of this make sense to anyone out there?
In theory, it makes sense. Based on about seven months of working with *, I'm under the impression additional work should be focused on various transmission levels and not just the pstn interface. In another week or two I'll have access to a high quality transmission test set, and am hoping to document some of the very items you've noted as well as others. The current levels are obviously usable, however I think the overall system and its interfaces can be improved to approximate a commercial pbx. Rich _______________________________________________ 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
