## 4 Experimental Results
### Prototype Loop Tests  
To evaluate the stand-alone performance of the developed prototype, a loop connection between the output of the pressure signal generator and the input of the pressure signal acquisition of the prototype parts was established. The tests that were performed evaluated the measurement errors caused by the variations in the following parameters: SBP, DBP and MAP; pulse envelope amplitude (AMP\({}_{\text{pulse}}\)); heartbeat rate per minute (HBR\({}_{\text{M}}\)); mean and standard deviation values; and the data acquisition sampling rate (SR). As an example, Table 2 represents the absolute and relative errors of the evaluation of the SBP, DBP, MAP and HBR\({}_{\text{M}}\) parameters for a synthesized oscillometric trapezoidal pulse envelope whose SBP, DBP and MAP, together with the maximum amplitude of the oscillometric pulses (AMP) values, were pre-defined as the values that appear in the first column of the table (SBP\({}_{\text{-}}\)DBP\({}_{\text{-}}\)MAP\({}_{\text{-}}\)AMP). The other parameters that were used for simulation purposes had the following values: PM = 180 mmHg, Pm = 50 mmHg, HBR\({}_{\text{-}}\)M = 90 b.p.m, dT = 30 s and SR = 100 S/s. The last column of the table (N\({}_{\text{-}}\)Peaks) represents the number of oscillometric pulses that were detected by the fixed ratio algorithm and then used to evaluate the BP parameters that are represented in columns two, three and four of Table 2. As can be easily verified from the table, the absolute error of the BP parameters that were evaluated is always lower than 1.8 mmHg, a value that is well below the pass clinical validation criterion defined by the British Hypertension Society (BHS), which is equal to 5 mmHg.  
Another set of experimental results is presented in Table 3. This table represents the absolute and relative errors of the evaluation of the SBP, DBP, MAP and HBR\({}_{\text{-}}\)M param  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**SBP\({}_{\text{-}}\)DBP\({}_{\text{-}}\)MAPAMP**} & \multirow{2}{*}{**SBP**} & \multirow{2}{*}{**DBP**} & \multirow{2}{*}{**MAP**} & \multicolumn{6}{c}{**Absolute Error (mmHg)**} & \multicolumn{6}{c}{**Relative Error (\%)**} & \multirow{2}{*}{**HBR\({}_{\text{-}}\)M**} & \multirow{2}{*}{**HBR\({}_{\text{-}}\)M**} & \multirow{2}{*}{**N\({}_{\text{-}}\)Peaks**} \\ \cline{5-12} \cline{5-12} \cline{5-12} \cline{5-12} \cline{5-  
eters for a synthesized oscillometric trapezoidal pulse envelope with SBP = 120 mmHg, DBP = 80 mmHg and MAP = 100 mmHg when the maximum amplitude of the oscillometric pulses (AMPs), which appear in the first column of the table (AMP), varies between 1 mmHg and 6 mmHg, with increments of 1 mmHg. The other parameters used for simulation purposes had the following values: PM = 180 mmHg, Pm = 50 mmHg, HBR_M = 90 b.p.m, dT = 30 s, and SR = 50 S/s (instead of value that was previously used, which was equal to 100 S/s). As previously referred to, the last column of the table (N_Peaks) represents the number of oscillometric pulses that were detected by the fixed ratio algorithm. In this case, for the lowest amplitude value of the oscillometric pulses, namely for AMP = 1 mmHg, which is an extremely low value in real measurement scenarios, the absolute error of the BP parameters reaches 11.6 mmHg, and it is not even possible to evaluate the HBR_M parameter (NaN) for the lower AMP value of 1 mmHg. Thus, for AMP = 1 mmHg and SR = 50 S/s, the absolute is higher than \(\pm\)5 mmHg. However, if the sampling rate is incremented to 100 S/s, the previous error of 11.6 mmHg is reduced to 2.6 mmHg, with the BHS criterion being verified. At the same time, it becomes possible to evaluate the HBR_M parameter, with the evaluated value being equal to 86.8 b.pm, which is 3.6% below the simulated value of 90 b.p.m.