Advanced Ionosonde


AIS ionosonde (Advanced Ionospheric Sounder) is an efficient, and simple as well, instrument capable to investigate Earth ionosphere. Designed and carried out employing the most advanced radar techniques, it allows to get an ionogram with only 250 W peak power, keeping dimensions and weight low with respect to similar instruments, and above all the reliability of the measurement due to the usage of coded pulses.  Various specimens of AIS are currently working in ionospheric observatories placed in different continents.

Main features

  • Radar system to perform ground based vertical soundings of ionosphere
  • Pulsed radar with digital coding
  • Single frequency sounding or scanning over a range of frequencies
  • Limited transmitted power
  • High vertical resolution
  • Coherent integration of received signals
  • PC control of sounding and signal processing


  • Resistive against ambient noise, using a complementary bi-phase code
  • Triple conversion receiver
  • Data acquisition on double channel (I-Q)
  • External transmitting amplifier (supplied)
  • “Delta” style Tx and Rx antennas, or other suitable types (not supplied)


Signal processing performed in the control PC by the machine control program

  • sounding control
  • signal processing to coherently integrate and extract the signal from of noise
  • graphic output and data storage

Automatic ionogram interpretation (“Autoscala” program)

  • sounding data acquisition
  • ionospheric parameters estimation
  • drawing of the electron density profile


Main technical features

Parameters Values
Frequency range of sounding 1÷20 MHz
Frequency resolution 25, 50, 100 kHz
Pulse coding 16 bit complementary bi-phase
Encoded pulse width 480 μs
Interpulse width (duty cycle) 8 ms (5.7 %)
Pulse Repetition Frequency (single code) 120 Hz max
Transmitted bandwidth ~ 67 kHz
Height range of sounding 90÷750 km
Height resolution ~ 5 km
Peak transmitted power (medium power) 250 W (15 W)
Receiver sensitivity ~ -85 dBm for 0 dB S/N
Receiver input dynamic range ~ 80 dB
Acquisition sampling rate 100 kHz
Acquisition quantization 8 bit
Coherent integration factor (In) 1-70 pulses
Frequency scan duration(In=50 and 50 kHz step) 3 minutes
Main power consumption ~ 100 W
Volume ~ 170 dm3
Weight 45-50 kg

Sample Ionograms

Some examples of ionograms acquired by AIS-INGV ionosondes placed at various ionospheric observatories. Many of them have a web site where it is possible to see ionograms in real time, for example: