Techniques for transmitting digital data on the spacelab's analog video channel

摘要

A study was made of various techniques for transmitting digital data over a composite video channel, with data from experiments on the Space Shuttle Orbiter in mind. Broadcast television telecommunications schemes and other techniques described in the literature were reviewed and compared. PSK (phase shift keying) MPSK (M-ary PSK), and or PAM (pulse amplitude modulation), which can be transmitted on visible lines of a frame, unassigned lines of the VBI (vertical blanking interval), or during the HBI (horizontal blanking interval), were all judged attractive under the proper conditions. However, PAM on visible lines or during the VBI should be relatively easy to implement, provide adequate average data rates, and give acceptable BERs (bit error rates).