Pole Star IF Processing

Figure 9 provides a global schematic of the IF processing in Pole Star.
Figure 9: Pole Star IF processing
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The 1.5 GHz output of each mixer is amplified ~30 dB by a low-noise, 1-2 GHz amplifier mounted to the cryostat's 12 K radiation shield (Figure 10). The amplifiers (designed by J. Kooi) are balanced and have a Lange coupler on their input, effectively eliminating the need for an isolator. Each signal is then amplified an additional 35 dB by room temperature Miteq amplifiers mounted on the dewar frame (Figure 11).
Figure 10: The opened dewar, with 3 x 810 GHz mixers.
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Figure 11: Room temperature amplifier box
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After passing through a 12 ft cable run the array IF's enter a 4-channel total power box (referred to as the `Quadbox' (Figure 12)). The Quadbox provides 60 db more amplification and contains a bandpass filter and crystal detector that permits the total power of each receiver channel to be measured either manually or under computer control. Once through the total power box, the 4 IFs enter an up/downconverter box which translates the 1.5 GHz IFs to 14.5 GHz and then down to 2.075 GHz, the center frequency required by the array Acousto-Optical Spectrometer (aAOS) (see the next section).
Figure 12: The quad total-power box
Click on the thumbnail for a full-size image!

Contact Chris Walker about the Pole STAR if chain

Last modified: Thu Sep 21 11:22:47 MST 2000

Figure 9 provides a global schematic of the IF processing in Pole Star.	Figure 9: Pole Star IF processing Click on thumbnail for full-size image!
The 1.5 GHz output of each mixer is amplified ~30 dB by a low-noise, 1-2 GHz amplifier mounted to the cryostat's 12 K radiation shield (Figure 10). The amplifiers (designed by J. Kooi) are balanced and have a Lange coupler on their input, effectively eliminating the need for an isolator. Each signal is then amplified an additional 35 dB by room temperature Miteq amplifiers mounted on the dewar frame (Figure 11).	Figure 10: The opened dewar, with 3 x 810 GHz mixers. Click on thumbnail for full-size image! Figure 11: Room temperature amplifier box Click on thumbnail for full-size image!
After passing through a 12 ft cable run the array IF's enter a 4-channel total power box (referred to as the `Quadbox' (Figure 12)). The Quadbox provides 60 db more amplification and contains a bandpass filter and crystal detector that permits the total power of each receiver channel to be measured either manually or under computer control. Once through the total power box, the 4 IFs enter an up/downconverter box which translates the 1.5 GHz IFs to 14.5 GHz and then down to 2.075 GHz, the center frequency required by the array Acousto-Optical Spectrometer (aAOS) (see the next section).	Figure 12: The quad total-power box Click on the thumbnail for a full-size image!