## 4 Determination of Rasterization Parameter Values
### Chirp-Z Transform (Chirp Transform)
2.2 Synthetic Signals Obtained by Decoding of the BMP File Subjected to the Differentiation Operation, Noisy by AWGN Noise  
The next stage of the simulation for synthetic signals was estimating the \(R_{H}\) parameter for image signals subjected to the differentiation operation as well as noisy by white noise for the set SNR values: +15, +5.0, \(-5\), \(-15\) [dB]. A 10-fold estimation was conducted for each case (Table 7). In the case of differentiated signals, as well as noisy by AWGN noise \(\text{SNR}<0\), the accuracy of determining the rasterization parameters, especially in the case of the test image in the form of the MS Word editor window, is not sufficient to use them directly in the coherent summation process. The values should be more precise, e.g., on the basis of determining the measure of image clarity. 2.3 Signals Obtained by Sampling the Revealing Signal from the VGA Interface Received by the TEMPEST Test System DSI-1550 and Sampled by the ADC Card  
Practical tests of the emission signals correlated with the information displayed on a computer monitor were carried out in the system shown in Figure 10. The computer set was placed in the shielding cabin on the measuring table. The tests used the TEMPEST Test System DSI-1550A measurement system (DSI-1550 RF Measurement System version 7.0.4.1 software) and a set of LZ1027A measurement antennas by Intriple: a vertical active rod antenna (100 Hz up to 50 MHz), a biconical active antenna (20 MHz up to 200 MHz), and a dipole active antenna (200 MHz up to 1000 MHz) with the IZ154B antenna switch (Figure 10). In order to sample the identified electromagnetic emission signals, a PDA-1000 8-bit analog-to-digital converter card, manufactured by Signatec (PDA100 Scope Application software, version 1.19), was used. The card offers a signal sampling rate of 1 GS/s, which may be reduced by using the card clock frequency division in the range from 2 to 1024. Using the test images (vertical \(8\times 8\) stripes and window of MS Word editor), the revealing signals of the line: graphics card-VGA cable-monitor, were recorded. The recording was performed at two reception frequencies: \(f_{o}=102\) MHz, where the strong emission from the cable was dominant, and \(f_{o}=424\) MHz, where the emission from the cable was suppressed. The signal was recorded using the sampling frequencies of the ADC card described in Section 2, in two reception bands: \(B=10\) and 20 [MHz]. The determined values of the \(R_{H}\) parameter were shown in Tables 8-10. \begin{table}
\begin{tabular}{c c c c c c c} \hline \multirow{2}{*}{**Image**} & **Receiving** & **Antenna** & **Sampling Rate** & **Real Line** & **Designated Line** & **Estimation** \\  & **Bandwidth** & **Amplifier** & **\(f_{s}\) [MS/s]** & **Length \(R_{H}\)** & **Length \(R_{H}^{\prime}\)** & **Length \(R_{H}^{\prime}\)** & **Inaccuracy** \\ \hline \multirow{8}{*}{Strips 8 \(\times\) 8} & \multirow{8}{*}{10} & & 62.5 & 925.920923 & 925.920893 & 0.000030 \\ \cline{3-6}  & & & 125.0 & 1851.841761 & 1851.841520 & 0.000241 \\ \cline{3-6}  & & & 250.0 & 3703.682958 & 3703.682158 & 0.000800 \\ \cline{3-6}  & & & 500.0 & 7407.363841 & 7407.367141 & 0.003300 \\ \cline{3-6}  & & & 62.5 & 925.920829 & 925.921599 & 0.000770 \\ \cline{3-6}  & & & 125.0 & 1851.841441 & 1851.246290 & 0.595151 \\ \cline{3-6}  & & & 250.0 & 3703.682739 & 3703.688339 & 0.005600 \\ \cline{3-6}  & & & 500.0 & 7407.364521 & 7406.767794 & 0.596727 \\ \hline \end{tabular}
\end{table} 
Table 8: Determination of the \(R_{H}\) parameter for the reception frequency \(f_{o}=102\) MHz, in the receiving band \(BW=10\) MHz, with the antenna amplifier on and off (\(+10\) dB). Figure 10: The real test system used to measure revealing emissions.