Alternative systems are disclosed for enhancing the signal-tonoise ratio in a signal storage tube. The intensity of the write beam is amplitude-modulated and it sweeps the target in a vertical raster. The read beam has a constant intensity and sweeps the target in a horizontal raster. In one embodiment, the video signal for one of a predetermined number of write lines is inverted and stored on the target in this inverted form thus translating the frequency band of the read signal to a higher value and out of the frequency range of noise caused by the physical characteristics of the target and the collection optics. In a second embodiment, a signal representative of the background noise is generated and subtracted from the output signal.