A system is described for recording the envelope of electron spin echoes and for obtaining the superhyperfine splitting of the electron resonance interval from the form of the envelope. The envelope modulation property on which this system depends is summarized briefly, the microwave system and logic systems used to record the envelope are described, and the problems encountered in making a Fourier transform of the envelope in order to derive the superhyperfine frequencies are discussed. The system was set up in order to make measurements on unoriented glass‐like samples. Some results obtained with samples of this type are shown.