The State Department said yesterday that Soviet encountering of test information in a missile launching several weeks ago does not appear to be a violation of the terms of the new strategic arms limitation treaty (Salt II).

Spokesman David Nall confirmed that the Soviets did encode some of the test data, or telemetry, in a recent launch of a submarine-based missile. However, he said "the United States has no basis for concluding" that a violation of SALT II terms was involved.

The SALT II treaty, Nall pointed out, does not ban all encoding of missile information. However, it does ban any encoding that impedes verification of compliance with the terms of the treaty.

In the case of a submarine-launched missile, Nall said, the SALT II treaty limits missile size and the number of reentry vehicles. If information concerning these characteristics were denied by encoding, said Nall, "we would know it."

An official who asked not to be quoted by name said "we haven't been denied anything we need to know" by the Soviett encoding.

Although the Senate has shelved debate on ratification of the SALT II pact because of the Soviet invasion of Afghanistan, the Carter administration has committed itself to observing the terms of the treaty for the time being. The Soviets, while making no public statement, also are believed to be observing the treaty terms for the present.