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Telos Zephyr Xstream Two-Way Radio User Manual

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USER’S MANUAL

Section 5: GUIDED TOUR of the MENUS 97

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 (or is

unreliable).

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 bit 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 to/from the original site). There will be no

lock or audio from the site associated with the second call. In this case, the second site should

drop the call, change rates to match, and redial.

Sample Rate

Thisisthedigitalsamplerateusedfortransmission/receptionbythecodecsection.Notethat

thisratemaynotmatchtheAES/EBUsamplerateusedontheinputoroutput.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ma

tched,youwillhavenolock,intermittentlock

loss,oraudiothatsoundspitchshifted.

w

IMPORTANT TIP!

1) Zephyr Xstream only supports the 24kHz sample rate in MPEG Layer-2 (or when used in

“IP streaming mode” -See Appendix 6 - Special Operational Modes for more on that

mode of operation).

Therefore, the Sample Rate menu does not have this option. The “L2 Half 64” Transmit

and Receive modes are used to achieve 24kHz operation in MPEG Layer-2.

2) The G.722 standard calls for a Sample Rate of 16kHz. This rate is used with G.722

regardless of the actual sample rate setting.

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