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A/Ds. All timing signals for EAR operation are generated by the timing generator inthe RC. The RC sends parameters of operation to the receiver and TRX.The SP performs a series of signal processing operations (pulse decoding, coherent integration,fast Fourier transform (FFT), incoherent integration), and sends the processeddata to the host computer (HC). The digitized I and Q signals are stored in the FIFO(First-In/First-Out) memory (double-buffered memory) in the A/Ds. The output is sentto the pulse decoding and coherent integration units with header data added. After pulsedecoding the digitized I and Q signals are coherently integrated for each beam and range.The coherent integration unit adds a specified number of I and Q signals and outputs32-bit data to double-buffered memory. The data from the ranges to be processed areselected and sent to the digital signal processing (DSP) unit. The integrated I and Qsignals are stored in the buffered memory of the DSP unit, and rearranged into timeseries at respective ranges. The DSP then performs complex FFT and power spectrumcalculations on these time series. The DSP also performs a specified number of incoherentintegrations of the power spectra. After incoherent integration the power spectra aresent to the HC. The HC sends operating parameters to the RC and controls start/stopof operation of the entire system. It also receives observed data from the SP and storethem to digital data storage (DDS) tape.ConclusionThe EAR has been continuously operated since July 2001, with some intermittentshort-term data gaps. The EAR is usually operated with a standard observation modeto observe the whole troposphere and the lower troposphere (2–20 km) with the time andvertical resolution of ∼90 sec and 150 m, respectively. The equatorial cross-tropopauseprocess is considered to play an important role on global stratosphere-troposphere exchange(STE). Observations by the EAR in the tropical tropopause layer (TTL) havebeen reported [Fujiwara et al., 2003; Yamamoto et al,, 2003]. The EAR is also capable ofviewing the ionosphere in directions perpendicular to the geomagnetic field, and it is thefirst one established in the Indonesian-Thai longitude sector (10.63 ◦ S, 171.93 ◦ E). Studieson field-aligned irregularities (FAIs) in the ionospheric E and F regions also have beenreported [Fukao et al., 2003b]. Additionally, the EAR has the capability to observe thinatmospheric structures by the frequency domain interferometry (FDI) or the frequencydomain interferometric imaging (FII) techniques. Many phenomena that remains to beuncovered in the equatorial atmosphere will be clarified by the EAR.ReferencesFukao, S., H. Hashiguchi, M. Yamamoto, T. Tsuda, T. Nakamura, M. K. Yamamoto,T. Sato, M. Hagio, and Y. Yabugaki, The Equatorial Atmosphere Radar (EAR): Systemdescription and first results, Radio Sci., 38(3), 1053, doi:10.1029/2002RS002767, 2003a.Fukao. S., Y. Ozawa, T. Yokoyama, M. Yamamoto, and R. T. Tsunoda, Firstobservations of spatial structure of 3-m-Scale field-aligned irregularities with theEquatorial Atmosphere Radar in Indonesia, In revision, J. Geophys. Res., 2003b.Fujiwara, M., M. K. Yamamoto, H. Hashiguchi, T. Horinouchi, and S. Fukao,Turbulence at the tropopause due to breaking Kelvin waves observed by the EquatorialAtmosphere Radar, Geophys. Res. Lett., 30(4), 1171, doi:10.1029/2002GL016278, 2003.Yamamoto, M. K., M. Fujiwara, T. Horinouchi, H. Hashiguchi, and S. Fukao,Kelvin-Helmholtz instability around the tropical tropopause observed with theEquatorial Atmosphere Radar, Geophys. Res. Lett., 30(9), 1476,doi:10.1029/2002GL016685, 2003.408