  A joint collaborative project was recently developed to provide the Madrid
Deep Space Communications Complex with a state-of-the-art wideband backend.
This new backend provides from 100 MHz to 6 GHz of instantaneous bandwidth, and
spectral resolutions from 6 to 200 kHz. The backend includes a new IF
processor, as well as a FPGA-based FFT spectrometer, which manage thousands of
spectroscopic channels in real time. All these equipment need to be controlled
and operated by a common software, which has to synchronize activities among
affected devices, and also with the observing program. The final output should
be a calibrated spectrum, readable by standard radio astronomical tools for
further processing. The developed software at this end is named "Spectroscopic
Data Acquisition Interface" (SDAI). SDAI is written in python 2.5, using PyQt4
for the User Interface. By an ethernet socket connection, SDAI receives
astronomical information (source, frequencies, Doppler correction, etc.) and
the antenna status from the observing program. Then it synchronizes the
observations at the required frequency by tuning the synthesizers through their
USB ports; finally SDAI controls the FFT spectrometers through UDP commands
sent by sockets. Data are transmitted from the FFT spectrometers by TCP
sockets, and written as standard FITS files. In this paper we describe the
modules built, depict a typical observing session, and show some astronomical
results using SDAI.
