# Landsat Surface Product Validation Instrumentation:
## 3 ASD and UAS Technology Assessment
### Precision
#### 3.1.2 Green Band  
Table 2 shows the results for the Green band for each ASD system individually. In this case, there are three systems. USGS EROS used a dual ASD system. This system employs one ASD to stare at a reflectance calibration panel while the other ASD is a mobile unit with an operator collecting data. However, USGS EROS processed the data collected by the mobile unit as if it were a single unit system, as well as a dual unit system. This is noted as 'EROS-Single' and 'EROS-Dual' in the table. SDSU used a traditional single unit system. Four bright targets were used for this band as follows: Permanflect 55%, RIT 30%, Asphalt, and Mystery Gray. In this case, bright targets ranged from 30% reflectance to 51%. Similarly dark targets were Permanflect 5%, RIT 2%, Alfafla, and Mystery Black. These targets ranged from 2% to 6% reflectance. Figure 9 compares the full range spectral profile (with 1-sigma error bars) of Permanflect 55% and 5% targets, representing a bright and a dark target, respectively. The spectral profiles of both Permanflect 55% and 5%, measured using the EROS and SDSU spectrometers, are similar. \begin{table}
\begin{tabular}{l l l l l l l l} \hline \multicolumn{1}{c}{} & \multicolumn{6}{c}{ASD (Rejectability–Green band)} \\ \hline \multicolumn{1}{c}{} & \multicolumn{6}{c}{Bright Bessel Rejectability} \\ \hline \multicolumn{1}{c}{} & \multicolumn{6}{c}{Permafflect 55\%} & RIT 30\% & Asphalt & Mystery & Average & Std. Dev. \\ \hline \multicolumn{1}{c}{} & Reflectance & 0.51 & 0.30 & 0.13 & 0.49 & & \\ \hline EROS & AM Difference & 0.016 & 0.019 & 0.006 & 0.025 & 0.015 & 0.010 \\ \cline{2-7} Single & Noon Difference & 0.005 & 0.013 & 0.003 & 0.033 & & \\ \hline EROS & AM Difference & 0.017 & 0.018 & 0.007 & 0.026 & 0.014 & 0.009 \\ \cline{2-7} Dual & Noon Difference & 0.007 & 0.010 & 0.002 & 0.029 & & \\ \hline \multirow{3}{*}{SDSU} & AM Difference & 0.019 & 0.014 & 0.015 & 0.024 & 0.012 & 0.007 \\ \cline{2-7}  & Noon Difference & 0.010 & 0.002 & 0.008 & 0.006 & & \\ \hline \multicolumn{1}{c}{} & \multicolumn{6}{c}{Part level Rejectability} \\ \hline \multicolumn{1}{c}{} & \multicolumn{6}{c}{Permafflect 5\%} & RIT 2\% & Alfafla & Mystery & Average & Std. Dev. \\ \hline \multicolumn{1}{c}{} & Reflectance & 0.06 & 0.02 & 0.05 & 0.03 & & \\ \hline \hline EROS & AM Difference & 0.001 & 0.002 & 0.002 & 0.000 & 0.001 & 0.001 \\ \cline{2-7} Single & Noon Difference & 0.000 & 0.001 & 0.002 & 0.001 & & \\ \hline EROS & AM Difference & 0.001 & 0.002 & 0.002 & 0.000 & 0.001 & 0.001 \\ \cline{2-7} Dual & Noon Difference & 0.001 & 0.001 & 0.002 & 0.001 & & \\ \hline \multirow{3}{*}{SDSU} & AM Difference & 0.001 & 0.001 & 0.002 & 0.000 & 0.002 & 0.001 \\ \cline{2-7}  & Noon Difference & 0.001 & 0.001 & 0.002 & 0.003 & & \\ \hline \end{tabular}
\end{table} 
Table 2: Green band precision results for individual ASD systems. To determine the repeatability, the key data point was the difference recorded between morning (AM) measurements and noon measurements, as shown in Table 2. Afternoon measurements were not utilized due to the extreme sky cloud cover on the afternoon of the first day of the campaign. Ideally, since all instruments/operators were measuring the same target, at the same time, two days in a row, zero difference would be recorded. In this case, differences, on average, tended to be 0.015 \(\pm\) 0.01 for bright targets and 0.002 \(\pm\) 0.001 for dark targets. In addition, morning differences are slightly larger than noon differences. This is likely due to the greater movement of the sun earlier in the day combined with the BRDF of the targets. Of special interest is the alfalfa target since it represents large vegetative targets that are likely to be used in operational land surface reflectance measurements. Results here tend to be similar between the alfalfa target and the various artificial targets. Table 3 shows the results for the Green band across all ASD systems. Again, only the morning (AM) and noon differences are used.