Equivalent Transmitter Power
The Equivalent Transmitter Power (ETP) was an indication of a fictitious transmitter power in the initial time of solid-state transmitters and indicates a pulse power that would have to be present in a short pulse with the pulse duration after pulse compression in order for this short pulse to have the same energy values as the real but longer intra-pulse-modulated pulse.
The reason for this specification is that solid-state transmitters cannot withstand such high voltages as vacuum tubes. In order to achieve a comparable range, these radar sets had to use much longer transmission pulses than usual in radar sets with transit time tubes. In the early days of solid-state transmitters, the specification of the very low pulse power was not conducive to sales, since the highest possible pulse power as a guarantee for long-ranges was often a selection criterion. For this reason, an equivalent transmitter power was often specified in addition to the real pulse power.
In practice, the equivalent transmitter power is the pulse power of the solid-state transmitter multiplied by the pulse compression rate. Conversely, the internal pulse compression rate can be estimated from the equivalent transmitter power and the real pulse power.