25 May 2004 To: Art Freiley From: Dick Simpson Subject: Noise Calibrations at DSS 14 Table below summarizes RSR results from noise measurements made at DSS 14. For 20 May, both X-RCP and S-RCP data have been analyzed; I will fill out the table as analysis of the remaining two channels is completed. The methods varied as I gained experience. For 13 and 20 May I compared nearby 5-minute intervals; longer averages did not appear to help, perhaps because of gain changes. In some cases (such as when the Noise Instrumentation was running), there was less than 5 minutes in an interval. Analysis of the 8 April data was not as careful; I took adjacent intervals, some of which were more than 30 minutes. The table shows the number N of different calculations (pairings), minimum and maximum values, and (sometimes) an average. In a small number of cases I compared one sky measurement against two ambient load measurements - or vice versa. N should thus be interpreted loosely - the amount of data going into each calculation varied, and not all of the results are independent. Ambient load data were compared against sky data to obtain Top. Sometimes the two intervals were adjacent, sometimes noise diode measurements fell between (up to 10 minutes spacing). Tndu is the noise diode temperature from comparing ambient load levels with levels when the noise diode was added to the ambient load. Tndl is the noise diode temperature from comparing sky noise levels (zenith) with and without the noise diode; a nearby Top was taken to be the reference. Channel Quantity Date N Minimum Maximum Average ------- -------- ---------- -- ------- ------- ------- S-LCP Tndu 2004-04-08 4 11.30 12.20 11.60 S-RCP Top 2004-04-08 3 19.75 20.27 S-RCP Tndu 2004-04-08 2 14.67 15.74 S-RCP Tndl 2004-04-08 2 16.25 16.34 X-LCP Top 2004-04-08 2 18.48 18.49 X-LCP Tndu 2004-04-08 2 16.25 16.34 X-LCP Tndl 2004-04-08 2 17.16 17.76 X-RCP Top 2004-04-08 3 19.60 19.85 X-RCP Tndu 2004-04-08 2 20.48 22.96 X-RCP Tndl 2004-04-08 2 21.58 22.20 S-LCP Top 2004-05-13 5 23.49 24.16 23.71 S-LCP Tndu 2004-05-13 3 12.07 12.93 12.58 S-LCP Tndl 2004-05-13 3 12.08 12.36 12.20 S-RCP Top 2004-05-13 7 19.08 19.28 19.13 S-RCP Tndu 2004-05-13 4 15.60 16.16 15.81 S-RCP Tndl 2004-05-13 4 16.06 16.10 16.09 X-LCP Top 2004-05-13 10 17.16 17.37 17.28 X-LCP Tndu 2004-05-13 3 15.35 17.31 16.28 X-LCP Tndl 2004-05-13 3 17.40 17.60 17.50 X-RCP Top 2004-05-13 1 18.34 X-RCP Tndu 2004-05-13 1 23.76 X-RCP Tndl 2004-05-13 1 23.58 S-RCP Top 2004-05-20 3 18.73 19.08 18.85 S-RCP Tndu 2004-05-20 5 14.83 16.49 15.99 S-RCP Tndl 2004-05-20 3 15.82 15.86 15.83 X-RCP Top 2004-05-20 5 18.38 18.67 X-RCP Tndu 2004-05-20 2 22.60 23.05 X-RCP Tndl 2004-05-20 2 23.25 23.37 Although there are some variations, the X-RCP and S-RCP results from 13 and 20 May look pretty consistent. In fact, on 13 May I could see no X-RCP differences across the entire test, so lumped all the measurements from each configuration into a single calculation (hence the N=1). I'll attach the S-RCP spreadsheet from 20 May to this message. I had sent the X-RCP spreadsheet with yesterday's report. As before, the first part of the spreadsheet gives the raw data - in the form of 8-point power spectra averaged over 10 seconds. Column A gives the center time in seconds from 0h; columns B-D give the center time in hh-mm-ss, rounded down to the nearest while second; and columns E-L ('windows' 1-8) give the power in each of the eight 3125 Hz spectral bins. There are 1410 rows, corresponding to 14100 seconds of data collection. Note breaks after rows 390 and 1110 when we stopped RSR recording. The raw data are color-coded: ambient load measurements are orange, ambient load plus noise diode are red, sky plus noise diode are green, and sky alone is blue; 'other' conditions are black. Blue and green were used to code data during the track. Rows 1412-1451 in the spreadsheet give averages over the color-coded ranges. For example, row 1414 gives the average values for the eight frequency ranges in rows 1-174 (22:11:04 - 22:39:54) at the top of the spreadsheet. Rows 1453-1491 give the corresponding standard deviations, and rows 1493-1532 give the ratios of standard deviations to averages expressed in percent. The values in row 1519 are large because the noise level dropped about 30 percent as the antenna went from its end-of-track position to zenith. The numbers used to calculate temperatures are shown in rows 1534-1573, column E. These are sums of the window values, except that columns H and I were omitted since they contain the spacecraft carrier during the actual track. Rows 1534-1536 columns G-H contain constants which you provided. Rows 1534-1538, columns J-L contain the physical temperatures of the ambient loads where the row number corresponding to the time the numbers were read is in column J. The corresponding Tamb values are listed in rows 1540-1543 columns J-K. The three estimates of Top are shown in rows 1545-1547, columns J-K. The first is derived from Tamb in row 1540 row L, the power measured in the ambient load configuration on row 1537 column E, and the sky power in row 1540 row E. Estimates of the equivalent noise diode temperature are shown in rows 1550-1560, rows J-L. Finally, the estimates of Tsys during the track are shown in rows 1562- 1568, columns J-L, where the first and second groups bracket the bistatic radar and the third (26.68K) was the value at the end of the track. I'll plan to FAX you copies of the plots which show log(power) versus time in S-RCP. The annotations indicate the spreadsheet rows corresponding to each time interval.