## 3 Simulation Tests Using Measurement Pool Simulator
In the case of Kasami codes, transmission with a BER less than 0.001 is impossible, but BER less than 0.01 can be achieved in a bandwidth of 1 kHz if the SNR is greater than \(-6\) dB. Using Gold codes, a BER less than 0.001 is possible for a bandwidth equal to 1 kHz when the SNR is no less than \(-2\) dB, and for a bandwidth equal to 2 kHz, when the SNR is no less than 6 dB. In the 8 kHz bandwidth, BER less than 0.01 is possible to obtain when SNR is not less than 8 dB. Figure 8: BER as a function of SNR for transmission in an UAC channel simulated using impulse response generated by 13 virtual sources. Figure 7: BER as a function of SNR for transmission in an UAC channel simulated using impulse response generated by 8 virtual sources. Figure 9: BER as a function of SNR for transmission in an UAC channel simulated using impulse response generated by 21 virtual sources. In 4 kHz and 5 kHz bandwidths, the assumed BER is not achieved, even with the use of BCH codes. In the UAC channel simulated with three or five virtual sources, the BCH-coded transmission was achieved with the assumed reliability using m-sequences in each frequency bandwidth. As the bandwidth increases, so does the required SNR. In the case of three virtual sources using Kasami codes, transmission with a BER < 0.01 is possible when the SNR is no less than \(-2\) dB for the 1 kHz bandwidth. In the case of higher bandwidth, reliable transmission is not possible. Using the Gold codes, it is impossible to obtain a coded transmission with a BER < 0.001 or BER < 0.01 for the 1 kHz, 5 kHz, and 8 kHz bandwidths. Such a transmission (BER < 0.001) is possible for the 2 kHz and 4 kHz bandwidth when SNR is no less than 0 dB and 8 dB, respectively. In the case of five virtual sources using Kasami codes, transmission with a BER < 0.01 is possible only when the SNR is no less than 2 dB and only for the 1 kHz bandwidth. Using the Gold codes, transmission with a  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Virtual Sources** & **Spreading** & \(\mathbf{B=1 kHz}\) & \(\mathbf{B=2 kHz}\) & \(\mathbf{B=4 kHz}\) & \(\mathbf{B=5 kHz}\) & \(\mathbf{B=8 kHz}\) & \(\mathbf{B=8 kHz}\) \\
**Sources** & **Sequence** & \(\mathbf{A}\) & \(\mathbf{B}\) & \(\mathbf{A}\) & \(\mathbf{B}\) & \(\mathbf{A}\) & \(\mathbf{B}\) & \(\mathbf{A}\) & \(\mathbf{B}\) & \(\mathbf{A}\) & \(\mathbf{B}\) \\ \hline \multirow{2}{*}{1} & m-sequence & \multirow{2}{*}{\(-20\) dB} & \(-20\) dB & \(-18\) dB & \(-18\) dB & \(-14\) dB & \(-14\) dB & \(-14\) dB & \(-14\) dB & \(-12\) dB & \(-12\) dB & \(-10\) dB \\  & Kasami & & \(-6\) dB & — & — & — & — & — & — & — & — & — \\  & code & & & & & & & & & & \\  & Gold & & & & & & & & & & \\  & code & & & & & & & & & & \\ \hline \multirow{2}{*}{3} & m-sequence & \multirow{2}{*}{\(-20\) dB} & \(-20\) dB & \(-18\) dB & \(-14\) dB & \(-14\) dB & \(-12\) dB & \(-10\) dB & \(-8\) dB & \(-4\) dB & \(-2\) dB \\  & Kasami & & & & & & & & & & \\  & code & & & & & & & & & & \\  & code & & & & & & & & & \\  & code & & & & & & & & & & \\ \hline \multirow{2}{*}{5} & m-sequence & \multirow{2}{*}{\(-20\) dB} & \(-18\) dB & \(-16\) dB & \(-14\) dB & \(-8\) dB & \(-6\) dB & \(-2\) dB & \(2\) dB & \(2\) dB & \(6\) dB \\  & Kasami & & & & & & & & & & \\  & code & & & & & & & & & \\  & Gold & & & & & & & & & & \\  & code & & & & & & & & & \\ \hline \multirow{2}{*}{8} & m-sequence & \multirow{2}{*}{\(-20\) dB} & \(-18\) dB & \(-16\) dB & \(-14\) dB & \(-8\) dB & \(-6\) dB & \(-2\) dB & \(2\) dB & \(10\) dB & — \\  & Kasami & & & & & & & & & & \\  & code & & & & & & & & & \\  & Gold & & & & & & & & & & \\  & code & & & & & &  
BER less than 0.001 can be achieved for the 1 kHz bandwidth and with a BER less than 0.01--for the 2 kHz bandwidth. In both cases SNR not less than 8 dB is required. In the case of the most complex impulse responses, based on 13 and 21 virtual sources, reliable transmission in the 8 kHz bandwidth is not possible regardless of the spreading sequence used, even if it is BCH coded.