Hoping to capitalize on concerns about the poor quality of children's television, the nation's most profitable cable network and the most-acclaimed producer of educational programming announced Tuesday that they would team up to start the first all-educational cable channel for children.

Nickelodeon, the highly popular children's network, and Children's Television Workshop, the producer of "Sesame Street" and other acclaimed shows, said they had formed a joint venture to create the network, called Noggin. It will be commercial-free, at least initially, and is scheduled to start appearing next January.How many cable operators will find room for Noggin in their already crowded systems is open to question, but Nickelodeon and the Children's Television Workshop hope that cable companies will be influenced by the current climate of dismay about the television programming that captures a large children's audience - from violent cartoons to the trash-talk confrontations of "The Jerry Springer Show."

Nickelodeon president Herb Scannell said he was confident that cable operators would make room for the new network eventually. "We're offering them something that's at the top of the American agenda now," he said. "Education is very important to Americans today. And we're bringing out something very dynamic and positive, as opposed to the broadcast industry, which is kind of in a resistance mode right now."

For years, only the nonprofit Public Broadcasting Service carried educational shows for children. The broadcast networks resisted, arguing that children would not watch them and therefore not enough advertising could be sold to make the shows profitable. But in 1996, the Federal Communications Commission passed a rule requiring broadcast stations (but not cable networks) to carry three hours of children's educational programs a week, as part of their public-service obligation. It took effect last fall.

Scannell and Children's Television Workshop president David Britt said that, in addition to drawing from their program libraries, each company would produce some new programs for Noggin's schedule, and they would also seek programs from outside producers.

"We keep hearing there are a lot of producers out there who are frustrated by not being able to get quality programs on the air," Scannell said. "Hopefully this will give them that opportunity."

The network will carry some programs made for pre-schoolers (ages 2 to 5 years) and some for older children, up to 14.

Neither Scannell nor Britt could say what new programs were envisioned for Noggin, or exactly how soon they could be produced.

And neither would say how much money would be put into the joint venture, or break down the percentage being invested by either side. But according to other company executives who spoke on condition of anonymity, the plan is to invest between $75 and $100 million over the next four years.

Analysts said that was a substantial figure, considering that the programming from their respective libraries will cost nothing.