Daily Image
14-11-2014
The Low Noise Tile's Reproducibility and averaged results
| Submitter: | Bert Woestenburg, Roel Witvers and Mark Ruiter |
| Description: | In our series of daily images on the progress of the Low Noise Tile (LNT) project (also see the AJDI of 21-03-2014 and that of 26-05-2014), we now present the results for a tile of one square meter (1m2), equipped with 48 of the new LNT elements. Measurements were done at four different azimuthal positions of the array, spaced at 45 degrees. Noise measurement results for the individual positions, as well as their average are presented, showing mean values below 45 K, with a standard deviation of 1-2 K. Furthermore, we present results on the reproducibility of noise measurements with the experimental 60-element Medium Sized Tile (MST), for one polarization of its 5x6 array. Seven measurements were done at one hour intervals during the day, between 9:30 and 15:30. Results of the individual measurements and their average show values below 45 K, with a standard deviation smaller than 1 K. As may be observed from the relevant noise plot, results for some of the measurements between 1150MHz and 1250 MHz that were strongly affected by RFI, have been omitted. These frequencies showed large noise temperature peaks in a number of measurements during the day, with much larger standard deviations. In the present results for the MST we observe a 5 K noise temperature increase, compared to the results in the AJDI of 26-05-2014. A possible explanation for this difference is the influence of low level RFI on the measurements, which is subject of further investigation. The third noise plot shows a comparison of the averaged noise temperatures for the 1m2 tile and the MST. The results are quite close to each other, indicating that the measurements on the smaller MST with respect to the 1m2 tile, give a good indication of the noise performance of a larger array. This allows lower cost and easier handling for this type of array experiments. |
| Copyright: | ASTRON |
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