Telos ZephyrExpress - Manual (Page 91)

CODING 5-13
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IMPORTANT!
The Layer 3 decoder in L3 STEREO mode requires that both ISDN lines be
connected and operating in order for the decoder to function. Until both lines
are present, the decoder will not output anything, even if the transmission
mode at the distant studio is not stereo. Any data drop outs would cause
interruption in both audio channels.
If your application requires the ability for the two channels to come and go
independently, such as when they are from independent sites, you must use
G.722 That is the only decode mode which supports fully independent
operation.
Dual Site Operation
It is possible to use the dual mono transmit mode to send to two receivers at different
sites. Set the transmit mode to
L3-DUAL and dial Line 1 at each site.
This topic is covered more thoroughly in section 7 (Menu Reference). Receive, if used,
must be set to the G.722 mode. The Layer II/III decoder is unable to accommodate the
independent signals.
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IMPORTANT!
You must make the call to the telephone number for Line 1. The mono Layer 2/3
decoder will work only with signals coming in on the first line.
Layer 2: Mono64kpbs vs MONO128; Dual vs JSTEREO
With one transmission path,
• The only usable L2 setting is monaural, at 64kbps ( L2 MONO64 ).
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COMPATIBILITY TIP!
Layer 2 Mono64 is called simply Layer 2 Mono on Zephyr.
With two transmission paths,
• L2 MONO128 provides the best Layer 2 quality by combining both transmission paths
to achieve a higher bitrate. This mode requires 2 data paths, or both ISDN lines.
• L2 STEREO mode is simply two simultaneous mono channels, with compensated
delay to preserve phase. Fidelity is identical to L2 MONO64 , since the algorithm can’t
take advantage of redundancy between the channels.
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COMPATIBILITY TIP!
Layer 2 Stereo is called Layer 2 Dual on some systems.