New satellite-based systems for ionospheric tomography and scintillation region imaging

The new constellation of radio beacons called Coherent Electromagnetic Radio Tomography (CERTO) will be available for measurements of ionospheric total electron content and radio scintillations. These beacons transmit unmodulated, phase-coherent waves, VHF, UHF, and L band frequencies. A fixed radio of 3/8 is used between successive frequencies. Total electron content (TEC) can be measured using the differential phase technique. The range between beacon and receiver is removed from the phase measurements, leaving a differential phase that is proportional to TEC. The three CERTO frequencies cover a wide range for determination of the radio scintillation effects caused by diffraction after propagation though ionospheric irregularities. All of the CERTO beacons are in low Earth orbit with inclinations ranging from equatorial to polar. Each satellite that carries CERTO has other plasma instruments that complement the beacon data. In addition, a Scintillation and Tomography Receiver in Space (CITRIS) instrument will be placed in orbit to detect signals from the CERTO beacons and from the array of 56 Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) VHF/S band radio beacons placed around the word by the French Centre National D'Etudes Spatiales. CITRIS will record ionospheric occultations and radio scintillations with a unique occultation and ground-to-space geometry. New algorithms have been developed for the multifrequency CERTO and CITRIS data to provide improved acquisition and analysis of TEC and scintillation data in ionospheric studies. The data from the CERTO constellation of beacons and receivers may be used to update space weather models.