The ionosphere extends from about 50km altitude to about 600km where it merges with near Earth space environment.The ionosphere is created by radiation, both electromagnetic and particles coming from the sun which ionise the Earth’s upper atmosphere into free electrons and ions.10 MHz and 1PPS in) Then a straight ethernet cable was used to connect both the PC and the USRP2 using their 1Gb Ethernet ports.An outside HF boradband antenna was added to the RX line of the USRP2.
By looking at the frequency axis an operator can determine the available comminations bands and the wich one will be subject to interference.
In this spectrogram as an example, the frequencies between 19-24MHz using a single reflection from the ionosphere would be available to a HF radio user to establish communications between Svalbard and Chilton.
Between 13 to 15MHz would also available utilising a propagation route that involves two reflections from the ionosphere and one reflection from the ground.
For our latitude (nort-west of Italy) we have decided to use Cyprus 2 wich has an intervall time of 300″ and a offset time of 240″.
You will need to calculate the great circle distance between your location and cyprus (or any other ionosonde). For this project we have used three main piece of hardware : The units are connected in this way : The GPS unit output (10MHz and 1PPS are connected to the USRP2 ext clock input Ref.
During the day it is ionized by solar radiation, during the night by cosmic rays.