The Model 630 is an assemblage of functional elements that are configured to assist the design and production engineer in testing data links. The Model 630 provides signaling interfaces that allow testing using serial pseudo-random data on a standard PCM data link or SGLS Command Link.

To test a SGLS Command Link using an external AM/FSK modulator, the Model 630 supplies the 1, 0, and S signals. Optionally, a GDP AM/FSK modulator is included in the unit. In that case the modulated baseband signal is provided for use in the system under test. The return link signaling is a similar construct. Either the ternary or AM/FSK signals are used.

A user selected pseudorandom data sequence is encoded to produce the ternary signaling needed for the SGLS data link. Using this technique, all three signaling elements are tested and error reports generated to identify weakness in the individual lines.

Independent transmit and receive sections permit the up-link to be operated at a different data rate from the down-link.