Unfortunately, the marina tests did not go as expected. The transmitter board, which was designed for small pulses, does not seem to handle the longer times and lower voltages involved in continuous-wave transmission. Only tests performed at nominal voltage produced usable data, but with significant power decay towards the end of transmission. On the other hand, this data was enough to verify correct operation of both the acquisition and symbol synchronisation algorithms, which is an extremely positive step towards a fully functioning modem. It was also enough to understand the interplay between the synchronisation algorithm and the transducer frequency response, which led us to implement a band equaliser to flatten the overall response seen at the receiver.

Apart from the tests, I used this week to convert the transmitter parameters which were still programmed at synthesis to configuration registers, in order to increase the flexibility of the system. This is now completely functional, and we will be able to get more data during the next round of testing.