DESIGN OF COMMAND LOGIC FOR A NEAR-EARTH SATELLITE.
Abstract
This report describes a command logic, known as the TADEX System (Tone-ADdress-EXecutive), which was designed for near earth satellites and successfully flown on DME-A (Explorer 31) and GEOS-A (Explorer 29). Audio frequency shift keying (AFSK) is used to encode an address plus sixty-four different messages. The tone bursts are transmitted to the spacecraft and decoded by the TADEX logic to control thirty-two ON/OFF relay functions. An 'address' tone gains access to the satellite and is followed by three 'executive' tone bursts. Each 'executive' tone burst is one of four 'executive' frequencies. A 'greatest-of' detector prevents high noise lovels from falsely registering a tone. Post-detection integration requires that the tone burst be present for at least 0.3 second, and a power one-shot requires that the command be completed no later than 4.3 seconds after receipts of the 'address' tone. These timing controls prevent spurious tone fragments from initiating a command. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1966
- Accession Number
- AD0635815
Entities
People
- Reginald M. Rhue
Organizations
- Johns Hopkins University Applied Physics Laboratory