EE 4984 Telecommunication Networks Project 1

Jeff Lazzuri and Stan Gutowski

Sega Channel is the first of its kind. It is the first interactive service, that provides video games on demand 24 hours a day to its subscribers. It began in 1994 as a consortium between Sega of America, Inc., Telecommunications, Inc. (TCI) and Time Warner Entertainment Company.


Sega Channel will provide Sega Genesis video games directly to the homes of it's subscribers. They will have access to the following features.

Sega Channel uses the existing compression technology in conjunction with the cable system interface to provide the users with almost instant access to their favorite games. The games are sent by the following procedures.

1. Information for the games sent via satellite

2. Special adapters with on-board memory connect the Sega Genesis to the cable signal coming in

3. The user selects which game he/she wants to play, via on-screen programming and the D-pad controller

4. The game is then downloaded to the respective Sega Genesis machine. This takes less than a minute.

5. The user can then play the game for as long as he/she likes as long as the unit is turned on.

NOTE: These games play exactly like the cartridges. They are not changed in any way.

Sega has also rated each game and supllied the parents with a password (4 digit pin#) if so desired.

Technical Information

The Sega Channel signal originates in Denver, CO. It is carried over the Galaxy-7 satellite, located 91.0 degrees W longitude using transponder 1 with horizontal polarization. It is then delivered to individual cable providers. It is currently in three major markets: Dallas, TX., Los Angeles, CA., and Atlanta GA.

The uplink signal is at a carrier frequency of 1.435 GHz and occupies 8 MHz bandwidth using QPSK modulation.

The downlink signal is at a frequency of 1.1 GHz and occupies 6 MHz bandwidth using QPSK.

Subscriber Loop

  • occupies two 3 MHz non-contiguous channels
  • data rate=6 Mbps
  • tunable to 68 different operating frequencies between 51 and 118 MHz
  • BER is <10E-06
  • uses Quadrature Partial Response (QPR) modulation

    QPR is a modulation scheme that uses a controlled inter-symbol interference. The receiver is capable of logically decoding the signal. QPR provides 20% better bandwidth performance than QPSK with only a minor increase in signal power.

    The only hardware required by the customer is the Sega Channel adapter designed by Scientific Atlanta. The adapter plugs into the Sega unit like a cartridge and is connected to the existing coaxial cable TV wiring and to an auxillary power supply. The adapter can be used on any 16 bit Sega Genesis unit.

    This adapter allows the customer to download the game selected in less than 1 minute. The adapter contains 4 MB DRAM, which will hold a game up to 32 Mb in size. Once the game is downloaded, it responds exactly as if it were a cartridge.

    Below is a block diagram illustrating the uplink/downlink operations.