In conjunction with TOKO video products presents:
How to Send and Recieve 128Kbps video UIA Inmarsat using two MTI TCS-7700 B terminals.
A proven MTI application.
Preface:
INMARSAT B technology and ISDN go together like hand and glove. The Inmarsat B technology was developed around ISDN (Integrated Services Digital Network) and is therefore very ISDN friendly. ISDN service on a base level is known as BRI (Basic Rate Interface). The services consist of two 64Kbps "B" (bearer) channels and one 16Kbps "D" (data) channel for a total of 144k of which only 128Kbps is used for data throughput.
In most cases people are interested only in 64Kbps data transfers over Inmarsat since not too many people are interested in carrying two units around or don’t have the resources to get two units. In this case it is sufficient for the owners of the terminal to access their resources via Internet, WAN, router or specialized equipment made for Inmarsat 64Kbps usage.
Others may need to transfer information at a higher rate of speed, for instance… video. 64Kbps will work with VTC (Video TeleConferencing) but 128Kbps is sometimes desired for enhanced video quality and this is where the beauty of ISDN comes in. ISDN is set up such that you can take two 64Kbps channels and bond them together for 128K. Typical methods for bonding the two 64Kbps channels come from the third party application devices because the B terminals are simply open data lines, or DCEs ready to respond to the needs of the third party DTEs. The remainder of this application note will guide you through the basics of a 128Kbps video session using two MTI TCS-7700 B terminals.
Equipment:
Method:
A demonstration 128Kbps session was set up in New York City with two MTI TCS-7700 B terminals locked on to the Atlantic West satellite with a VAST – VTC terminal set up in the dual 64Kbps mode. A multiple head cable with V.35 to RS-530 converters was connected to each of the TCS-7700s. Another TOKO VAST – VTC terminal was set up in Chicago at the TOKO headquarters, ready to accept an ISDN call.
First, the VAST – VTC Primary 1 channel was initialized on one B unit by dialing the TCS-7700 with the first ISDN number to start the call. Once this was established the VAST – VTC Primary 2 channel was initialized by dialing the second TCS-7700 to connect to the second ISDN number. A128K VTC session successfully followed.
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© Mobile Telesystems, Inc. 1998.