Results are presented from the HF electrostatic wave detection experiment flown on the PORCUPINE F3 rocket. In this experiment, we measured the cross spectrum of natural random high-frequency waves received on two small dipoles. We observed natural electrostatic emissions around the three-halves harmonic of the electron gyrofrequency ( fb) and also around the upper hybrid frequency ( fuh). A linear calculation shows that the amplitudes of these emissions are above the thermal noise level for the plasma. To explain the observations, it is necessary to take into account, in addition to the cool isotropic plasma, the presence of low-energy precipitating suprathermal electrons (1--20 eV). It appears that these electrons are highly anisotropic and enhance greatly the noise around 3/2 fb. However, the electron distribution function remains stable and the most intense emissions are observed around fuh.