Abstract: A time of flight mass spectrometer includes an ion source (10) a lens system (18, 19) to focus the ions into a beam (21), an orthogonal accelerator (22) comprising two parallel electrodes one of which is a grid through which ions are deflected into a main accelerator and into a flight tube (26). At the distal end of the flight tube (26) is located an ion detector (27) which enables the measurement of the time of flight of ions from the orthogonal accelerator (22) to the detector (27).

Abstract: The invention is concerned with the detection of the presence of narrow pulses in an electrical signal such as that derived from a limited band width receiver. A first discriminator is provided for discriminating against pulses other than those having a ratio of amplitude to width characteristic of a desired narrow pulse. A second discriminator is provided for discriminating against pulses other than those having a width characteristic of a desired narrow pulse and a third discriminator is provided for discriminating against pulses other than those which have a symmetry characteristic of a desired narrow pulse. The input is applied to the first and second discriminators in parallel with the third discriminator arranged to be effective only for those pulses which have not been discriminated against by the first and second discriminators.