13. The invention as set forth in claim 12 wherein said heterodyne detector includes a variable frequency oscillator, and means for applying said vertical sweep signal to said oscillator for changing the frequency thereof in synchronism with said segments.
12. The invention as set forth in claim 8 further comprising timing and control signal generating means including a clock oscillator connected to said compressing means for establishing the factor by which said input signals are compressed in time, at least three counters, means for connecting said counters to each other in succession such that the first of said counters counts said clock and provides first and second pulses at the beginning and end of said segments respectively, said second counter counts said second pulses and provides a third pulse after counting a number of said second pulses equal to said plurality of frequency ranges to said third counter, and means for applying said first and second pulses to said fast horizontal sweep generating means, the output of said second counter to said vertical sweep generating means and the output of said third counter to said slow horizontal sweep generating means.