Internet Voice Distribution System (IVoDS)
Developed for Marshall Space Flight Center
(MSFC) Flight Projects Directorate (FPD)
to support International Space Station (ISS)
communications, IVoDS allows Internet-based
participants to talk/listen on one conference
while listening to seven others. This multi-conferencing
system links researchers, NASA Operations
Personnel, and ISS crew together to support
collaboration during Space Station experiment
operations & planning.
 The
core component of IVoDS is the CUseeMe Conference
Server. It establishes H.323 connections
with the clients, mixes the audio from all
talkers, and sends the audio out to all
listeners. The gateway, developed by VoIP
Group, converts audio between the telephony-based
MSFC FPD Voice Switch and the H.323 IP-based
conferencing system. AZ Technology developed
the IVoDS-unique software to interface with
and control the Conf. Servers, maintain
the user database, authenticate users, and
control talk authority on Air/Space-to-Ground
conferences (PAYCOM). In addition, AZ Technology
developed the IVoDS Client that provides
the interface to the end-user. AZ Technology
is the IVoDS prime contractor.
An IVoDS Administrator creates the conferences,
adds/maintains user accounts, and monitors
conference activity. The PAYCOM has the
means to quickly disconnect a user from
a restricted conference, if desired.
All Clients connect to the Conf. Server
using the H.323 protocol for call signaling
and media control. All audio packets are
compressed using a G.723 codec (code/decode
algorithm). All access between the IVoDS
Client and the Admin/Conf. Servers takes
place through a VPN (virtual private network).
Each audio stream requires a bandwidth of
39Kbps (kilobits per sec).
IVoDS Client Interface
The client contains 8 rows of identical
conference-related controls. Users can connect
to 8 voice conferences and independently
adjust volume and muting for each. The green/red
LED's signify both connection status and
talk activity. Before being allowed to connect
to any conference, users must login with
a valid username/password. The column of
"Talk" radio buttons assures users
talk in only one conference at a time. While
users talk and listen in the "talk"
conference, they can still hear the other
seven conferences.
|
