Noise limitations in digital recording

Previous studies have shown that the tape limited signal/noise ratio (s.n.r.), which may be deduced from first principles, is in close agreement with practice on many modern recorders. This s.n.r. depends upon the medium properties and the recording format, in particular the trackwidth and bandwidth. Since the digital linear density usable is related to the bandwidth, it is possible to derive expressions linking the s.n.r., trackwidth, linear and area digital densities. It is concluded that the s.n.r. available at an area density of 107bits/in2, which is a factor of ten higher than present maxima, is still adequate to permit reliable digital recording.