Abstract:

In order to meet requirements of spacecraft tracking, telemetry and command (TT&C) transponder in direct sequence spread spectrum system, the code tracking loop is investigated. A new code tracking loop is presented which adopts a new kind of dot product power discriminator and a new pseudocode generator in which the phase can be accurately adjusted. Moreover, the related distance and bandwidth of code tracking loop will adaptively switch to solve the contradictions between locked timers, convergence range and tracking accuracy. Furthermore, a new implementation method of code tracking loop is proposed in which discriminator and loop filter are timesharing same arithmetic unit. Simulations and measurements are given.

Key words: spacecraft, transponder, direct sequence spread spectrum, code tracking loop