## 4 Evaluation of the Accuracy Characteristics of the Device for Measuring Radio Signal Samples  
It follows directly from formula (1) that the change in the intensity level of the optical field in the plane of the interferogram, manifested as a shift of interference fringes in its plane must be estimated at points \(l_{\Sigma}(x,\ t)=l_{0}\). The value of shift of interference fringes depends on the parameters of the input radio signal and the dependency \(l_{\Sigma}(x,\ t)\) has the greatest steepness along the line of photodetectors. Coordinates of the specified points at \(U(t)=0\) are determined from the solution of the equation:  
\[\frac{2\pi\cdot l_{0}}{\lambda}\Bigl{[}\delta_{1}\Bigl{(}x_{0}^{(q)}\Bigr{)}- \delta_{2}\Bigl{(}x_{0}^{(q)},t\Bigr{)}\Bigr{]}=\frac{\pi}{2}+\pi\cdot q,\ q= \pm 1,\pm 2,\ldots. \tag{9}\]In \(U(t)\
eq 0\) the specified points are shifted by an amount \(\Delta x_{q}\), defined by the expression:  
\[\Delta x_{q}=\frac{\Delta l(t)}{\delta_{1}^{\prime}\left(x_{0}^{(q)}\right)- \delta_{2}^{\prime}\left(x_{0}^{(q)},t\right)},\ q=\pm 1,\pm 2,\ldots. \tag{10}\]  
where \(\delta_{1}^{\prime}\) and \(\delta_{2}^{\prime}\) denote the derivatives of the corresponding functions.  
The specified offset will lead to a change in the intensity of the optical field at the points \(x_{0}^{(q)}\) by the amount of \(\Delta I_{q}\) (\(q=\pm 1,\pm 2,\ldots\)):  
\[\Delta I_{q}=-\frac{2\pi\cdot l_{0}}{\lambda}\cdot I_{1}\cdot\left[\delta_{1} ^{\prime}\left(x_{0}^{(q)}\right)-\delta_{2}^{\prime}\left(x_{0}^{(q)},t \right)\right]\cdot\sin\biggl{\{}\frac{2\pi\cdot l_{0}}{\lambda}\Bigl{[} \delta_{1}(x_{0}^{(q)})-\delta_{2}(x_{0}^{(q)},t)\Bigr{]}\biggr{\}}\Delta x_{q}, \tag{11}\]  
The resulting change \(\Delta I_{q}\) can be registered and measured using a photodetector 6, provided that it exceeds the quantization discretion of the ADC. This condition can be written in the form \(k_{PD}\cdot\Delta I_{q}\geq\Delta u\), where \(k_{PD}\) is the conversion coefficient of the photodetector. In this case, the quantization error is \(\Delta u/2\). Thus, the minimum change of value \(U(t)\), which can be registered by the optoelectronic device in question is determined by the expression:  
\[\frac{2\pi\cdot l_{0}}{\lambda}\cdot k_{\rm PC}\cdot I_{1}\cdot\frac{L\cdot \left\{\text{tg}\Bigl{[}\arcsin\left(\frac{\sin\alpha_{1}}{n_{0}-k_{\rm IT2} \cdot l_{\rm min}}\right)\Bigr{]}-\text{tg}\alpha_{20}\right\}}{\left(\frac{L }{2F}-1\right)^{2}\cdot\text{tg}\alpha_{1}}=\Delta u,\ q=\pm 1,\pm 2,\ldots. \tag{12}\]  
The ratios (4)-(12) allow us to establish a relationship between the quantization step of an optoelectronic device and the discrete step of an ADC, respectively, in the form of:  
\[\frac{U_{\rm min}}{\Delta u}=\frac{\lambda\cdot n_{0}^{2}}{L\cdot k_{\rm PC} \cdot k_{\rm IT2}\cdot\cos\alpha_{1}\cdot\left(\delta_{1}(x_{0}^{(q)})-\delta _{2}(x_{0}^{(q)},t)\right)}\cdot\left(\frac{L}{2F}-1\right)^{2},\ q=\pm 1,\pm 2,\ldots \tag{13}\]  
Thus, the choice of parameters of the optical part of the optoelectronic device \(\alpha\), \(\alpha_{0}\), \(\alpha_{1}\), \(\lambda\), \(n_{0}\), \(L_{1}\), \(F\), \(R_{1}\) allows you to change the quantization step when evaluating radio signal samples. Of the entire set of these parameters, the parameters \(\alpha_{1}\) and \(R_{1}\) have the greatest impact on the gain in the accuracy of the evaluation. These parameters determine the curvature of the wavefront of the signal light flux when exposing a Fourier hologram. When forming a holographic interferogram, this causes a high sensitivity of the spatial-spectral distribution of the intensity of the optical field to the estimated readings of the received radio signal. At the same time, the value of \(L_{1}-2F\) it should not be too small, since the distance between the interference maxima increases, which leads to an increase in the linear dimensions of the interferogram.