‘Signal analysers’, as follows: 1. ‘Signal analysers’ having a 3 dB resolution bandwidth (RBW) exceeding 10 MHz anywhere within the frequency range exceeding 31,8 GHz but not exceeding 37 GHz; 2. ‘Signal analysers’ having Displayed Average Noise Level (DANL) less (better) than - 150 dBm/Hz anywhere within the frequency range exceeding 43,5 GHz but not exceeding 90 GHz; 3. ‘Signal analysers’ having a frequency exceeding 90 GHz; 4. ‘Signal analysers’ having all of the following: a. ‘Real-time bandwidth’ exceeding 170 MHz; and b. Having any of the following: 1. 100 % probability of discovery, with less than a 3 dB reduction from full amplitude due to gaps or windowing effects, of signals having a duration of 15 μs or less; or 2. A ‘frequency mask trigger’ function with 100 % probability of trigger (capture) for signals having a duration of 15 μs or less; Technical notes: 1. Probability of discovery in item 1. above is also referred to as probability of intercept or probability of capture. 2. For the purposes of item 1. above, the duration for 100 % probability of discovery is equivalent to the minimum signal duration necessary for the specified level measurement uncertainty. Note : The category above does not apply to those ‘signal analysers’ using only constant percentage bandwidth filters (also known as octave or fractional octave filters).