The e-POP Radio Receiver Instrument on CASSIOPE

The Radio Receiver Instrument (RRI) is a four-channel digital receiver fed by four 3-metre monopoles, arranged in a crossed configuration, each connected to a high input impedance preamplifier. The RRI bandwidth extends from 10 Hz to 18 MHz. The receiver measures the electric fields of either spontaneous radio emissions or waves created by ground transmitters, such as ionosondes, high-frequency radars and ionospheric heaters. In order to measure accurately the intensity, frequency, direction of propagation and signal delay of such fields over the broad frequency range, modern digital receiver technology is employed. The amplified signals from the monopoles are digitized at a rate of 40 megasamples per second, and from there on, the signal is down-converted, filtered, time-stamped and communicated in digital form. The characterization results of the RRI flight model are reported. Formats for data commands for configuring the digital receiver and for data output are described.