Telos Zephyr Xstream, User Manual

Page: 91 / 381

USER’S MANUAL
Section 4: BASIC OPERATION & INSTALLATION 79
c
COMPATIBILITY TIP!
The Zephyr Xstream specifies the bit rate per channel. Since certain modes (i.e. stereo or
mono-128) require two channels to operate, the total (aggregate) bit rate would be double the
number displayed in these cases.
This is important as some other brands of codecs specify the total bit rate.
Since the network must accommodate the rate selected, it is important to hang up (i.e. drop the
call) and redial if this parameter is changed during a call.
i
ISDN TIP!
Since this parameter specifies the bit rate placed over the dial up data network, it is
important to understand the following: In some areas of the USA & Canada, only 56kbps or
64kbps service may be available. In addition, since different network paths (trunk groups) are
sometimes used for the two rates, there are times where one rate may provide more reliable
connections than the other.
In our experience, the only sure way to know if a connections at a given between to particular
points will work, is to try it. First at 64kbps, and then at 56kbps, if the higher rate fails
.
h
HOT TIP!
Since the network has to know the bit rate for a given call, this information is available to the
Xstream on incoming calls. Therefore, the Xstream will switch to the rate of the incoming
call.
There is one exception however. If the Xstream already has a call in progress at a given rate,
and a second call comes in (i.e. from a third codec) the unit will accept the call, but will not
change rate (since that would cause a loss of audio from the original site). There will be no
lock or audio from the site associated with the second call. In this case, the second remote
site should drop the call, change rates to match, and redial - All three units must be at the
same Bit Rate for this to work.
Sample Rate
This is the digital sample rate used for transmission/reception by the codec section. Note that
this rate may or may not be the same as the AES/EBU sample rate used on the input or output.
See Section 11 (Detailed Menu Reference) for information on using the AES/EBU ports. The
sample rate must be matched between your Zephyr Xstream and the codec at the far end for
successful audio transmission.
If the sample rate is not matched, you will have no lock, intermittent lock loss, or audio that
sounds pitch shifted.