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Firmware testing of ARTS SC4 IQUV output

Submitter: Jonathan Hargreaves
Description: DESP end-to-end tests are used to check the integrity of the signal paths through the ARTS firmware, from the analogue-to-digital converter to the data recorder.

Now, as well as varying the frequency and amplitude of the test signal, we can change its phase. Recently this feature was used to check the Stokes U and V outputs from the ARTS science case 4 firmware.

In this test, sinusoids with identical amplitude and phase were applied to both the X- and Y-polarization inputs. The phase of the Y-pol was held steady, while the X-pol phase was swept through 360 degrees, in 2 degree steps. The results indicate that U and V respond inusoidally to the input phase difference, with a 90 degree offset.

This is what we expect, give or take a sign error.
Copyright: J Hargreaves, P Donker
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