## 4 Simulation Tests Using Watermark Replay Channel Simulator
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Spreading** & **BER** & **Transmission** & **BCH Code** & **Transmission** & **BCH Code** & **Transmission Rate** \\
**Sequence** & **No ECC** & **Rate** & **Rate** & **Rate** & **Rate** & **Rate** \\  & & **No ECC** & **BER < 0.01** & **BER < 0.01** & **BER < 0.001** & **BER < 0.001** \\ \hline \hline  & \multicolumn{6}{c}{**Bandwidth = 1 kHz**} \\ \hline m-sequence & \textless{}0.001 & 3.92 bps & — & 3.92 bps & — & 3.92 bps \\ \hline Kasami code & \textless{}0.001 & 3.92 bps & — & 3.92 bps & — & 3.92 bps \\ \hline Gold code & \textless{}0.001 & 3.92 bps & — & 3.92 bps & — & 3.92 bps \\ \hline  & \multicolumn{6}{c}{**Bandwidth = 2 kHz**} \\ \hline m-sequence & \textless{}0.001 & 7.84 bps & — & 7.84 bps & — & 7.84 bps \\ \hline Kasami code & 0.01 & 7.84 bps & 4/7 & 4.48 bps & 5/15 & 2.61 bps \\ \hline Gold code & 0.05 & 7.84 bps & 5/15 & 2.61 bps & 6/31 & 1.52 bps \\ \hline  & \multicolumn{6}{c}{**Bandwidth = 4 kHz**} \\ \hline m-sequence & 0.33 & 15.69 bps & 12/2047 & 0.09 bps & \textgreater{}13/4095 & \textless{}0.05 bps \\ \hline Kasami code & 0.26 & 15.69 bps & 11/1023 & 0.17 bps & \textgreater{}12/2047 & 0.09 bps \\ \hline Gold code & 0.34 & 15.69 bps & 12/2047 & 0.09 bps & \textgreater{}13/4095 & \textless{}0.05 bps \\ \hline  & \multicolumn{6}{c}{**Bandwidth = 5 kHz**} \\ \hline m-sequence & 0.36 & 19.61 bps & 12/2047 & 0.11 bps & \textgreater{}13/4095 & \textless{}0.06 bps \\ \hline Kasami code & 0.36 & 19.61 bps & 12/2047 & 0.11 bps & \textgreater{}13/4095 & \textless{}0.06 bps \\ \hline Gold code & 0.33 & 19.61 bps & 12/2047 & 0.11 bps & \textgreater{}13/4095 & \textless{}0.06 bps \\ \hline  & \multicolumn{6}{c}{**Bandwidth = 8 kHz**} \\ \hline m-sequence & 0.38 & 31.37 bps & \textgreater{}13/4095 & \textless{}0.1 bps & \textgreater{}13/4095 & \textless{}0.1 bps \\ \hline Kasami code & 0.40 & 31.37 bps & \textgreater{}13/4095 & \textless{}0.1 bps & \textgreater{}13/4095 & \textless{}0.1 bps \\ \hline Gold code & 0.38 & 31.37 bps & \textgreater{}13/4095 & \textless{}0.1 bps & \textgreater{}13/4095 & \textless{}0.1 bps \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Results of simulation tests using Watermark software; NOF1 channel. Similarly, as in the tests with the measurement pool simulator, the best BER results were obtained for the DSSS signal bandwidth equal to 1 kHz. In this case, the use of each of the spreading sequences makes it possible to achieve a BER less than 0.001 on each tested channel. The possible transmission rate corresponding to such bandwidth is 3.92 bps (Table 1). In the bandwidth equal to 2 kHz, a BER less than 0.001 was obtained for the NCS1 and BCH1 channels, regardless of the spreading sequence. In the case of the NOF1 channel, this result was possible to obtain using only the m-sequence. In other cases, the BER was no higher than 0.05. Thus it can be improved to less than 0.001 using the BCH coding of maximum code rate equal to \(6/31=0.1935\), reducing the transmission rate from 7.84 bps to 1.52 bps in the KAU1 channel. For a bandwidth equal to or greater than 4 kHz, a significant deterioration in the obtained bit error rate was observed. The BER value of rank 0.3 cannot be improved to a level of less than 0.01. This would require BCH code with a code rate of rank \(12/2047=0.0059\) or \(13/4095=0.0032\), which would reduce the bitrate to less than 0.1 bps, which, in turn, would make such a UAC system useless. Among all the tests carried out in the Watermark simulator, the highest transmission rate (equal to 7.84 bps) with reliability expressed as BER less 0.001 was obtained in the 2 kHz bandwidth using the m-sequence in the NOF1 channel and with any 8-order sequence in the NCS1 and BCH1 channels.