Ionosonde is the generic name for ionospheric sounders using the basic techniques of radar to detect the density of the ionospheric plasma as a function of time. The device emits pulses of electromagnetic energy by doing a scan in frequency between 1 and 30 MHz (reaching up to 40 MHz) in steps of 50 or 100 kHz. By measuring the elapsed time between the signal emitted and reflected signal, with an ionosonde provides a transmission electron density profile as a function of time (virtual). The digital ionosonde also have the ability to measure the phase of the signal and its Doppler shift, allowing thus to obtain information about the dynamics of ionospheric reflecting region. The digital ionosonde digisonde are high-capacity data processing shortly after its acquisition, which allows its use in programs that require ionospheric information in real time, such as the Space Weather forecast.
The integrated system consists of Digisonde transmitter, receiver, an antenna switch, internal computers, peripherals, and transmitting and receiving antennas. The electromagnetic signal is transmitted vertically to the ionosphere, with peak power of the order of 10 kW (for Digisonde DGS256) and the order of 300 W (for models and DPS-4 SDS-4D) through a transmitting antenna type Delta with 600 ohm resistive load with center tap. The reflected signal is received by a set of receiving antennas (4 or 7, depending on the configuration adopted).