Telos Zephyr Xstream - Manual (Page 291)

USER’S MANUAL
Section 13: Deep Tech Information and Troubleshooting 279
• ISDN
This option causes two different things to happen.
a) Data coming in the ISDN interface (when INTERFACE is set to ISDN )
is sent back out the same channel(s) of the interface. Therefore, the
unit on the other end should be able to receive its own audio back
(assuming it is configured for compatible Transmit and Receive
modes). If this is the case, the network path is functioning.
b) Codec data from the encoder is passed back to the decoder (when
INTERFACE is set to ISDN). Therefore, you should receive your own
audio back (assuming it is configured for compatible Transmit and
Receive modes) with delay and quality dependant on the coding
mode used. This tests over 70% of the Xstream's functionality.
This mode can be used to audition the various coding modes even when no
ISDN circuit is present.
A
U
D
I
O
DECODER
OFF
ON
OFF
ON
ENCODER
clk
TxD
RxD
RxC
TxC
clk
data
data
audio
audio
Xstream
SEND
RCV
OFF
ON
OFF
ON
ISDN
Interface
AUDIO LOOPBACK
SWITCHES
ION IOFF
ISDN LOOPBACK
SWITCHES
The AUDIO and ISDN loopback modes are illustrated above. The
switches on the left side are activated for the AUDIO LOOPBACK
mode while the switches on the right are activated for the ISDN
LOOPBACK mode.