A special purpose decoder and display unit is designed to present special format radar signals for training. Several display formats ease operator workload while acquiring desired radar formats. A reference tone is recorded along with radar signals on a tape and a phase locked oscillator receives the reference tone which has the same fluctuations that the recorded radar signals have. A controlled computer and the phase locked oscillator feed their signals to a frequency synthesizer that creates a fine tuned signal based on the output signals of the phase locked oscillator and the computer. A timing generator is coupled to receive the output of the frequency synthesizer and it generates special purpose timing signals which are fed to a display. A video input receives radar signals coming from the tape, for example, to generate a sense directed, gain controlled video signal. A planned position indicator converter receives the gain controlled video signal and processes the signal from polar to rectangular coordinates in accordance with directions from the control computer so that a display unit can appropriately show the information contents of the video input signal without the wow and flutter that might otherwise be attributable to speed inconsistencies of the tape.