The Medicina IRA-SKA Engineering Group

The band-limited signal is down converted to the video band, filtered again, digitised (8 bit), and
sent, via a low-cost optical link, to the data processing room, distant about 900 m (worst case). A
sum of every single receiver inside the single channels is sent to the already existing IF stages.
4.1.2 Eight single receivers on each reflector:
In this solution we consider 8 single receivers on each single cylindrical reflector. The number of
receivers installed on the total N/S would be 512 as in the previous case. This is the maximum
number of receivers installable on the N/S arm without changing the focal line design. Due to the
mechanical structure of such an antenna, it should be very easy to change (if requested) the old
dipoles with a new design low-cost wide-band printed sensors on the same focal line. In this case
more than 4500 receivers could be installed. The block schematic diagram is visible in Figure 4.5.
The Vector Modulator is not needed in this solution because each phase and amplitude can be
numerically adjusted in the digital beamformer.
Figure 4.5: Bock diagram of the version with eight separate receivers.
In Figure 4.6 is reported a pictorial view of the 8 receivers, from the focal line down to the cabin
housing the existing receivers. In Figure 4.7 a more detailed block diagram is shown. The Signal
coming from the dipoles is fed to the LNA, filtered (BW=10 MHz) by a cost-effective multipole
ceramic filter, amplified (18 dB) and filtered and amplified again. The signal is down converted to
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