Hello, everyone! This week, we actually met with a professor from another engineering school in Lisbon, who we sought because they had been the supervising teacher for a student writing their Msc. thesis on the same topic we are working on. Pretty cool, right?
Also, now that we received the material we requested, we are now working at full pace, which has been quite exciting!
So, we had been planning this meeting for a while, and it eventually happened. Firstly, we met with a telecommunications expert, who clarified a lot of things for us. We started talking about software and the way we will modulate the signal, and we were given some ideas, such as implementing coherent reception. Then, we were also recommended not to use a signal between 1 and 0, but given the complexity of these upgrades and the fact that we don’t really need them for now, we chose not to make the suggested adjustments, i.e., we wil keep using OOK with NRZ.
However, we did follow the expert’s suggestions in the hardware department. The big piece of advice we were given was to add an active filter to the circuit because it minimizes the noise “heard” in the reception of the signal due to the fact that it both filters and amplifies the signal at the same time; before, we amplified it first and then filtered it, but that ends up worsening the noise problem, actually, because the amplification adds noise that is then caught in the filter (which we don’t really want).
Other than this, we also talked about using either LEDs or lasers as emitters - as you know, we were already pretty sure we would use the LEDs, but it is always good to explore all possible options. The teacher told us that the lasers could actually have a diffusion angle wide enough to be used in this application (about 10 to 12º), which could make them better than the LEDs, given the lasers’ really intense light, but we found one big flaw that hadn’t crossed our minds until the meeting - the laser has a very long loading time for each beam that is sent between ON-OFF states, which isn’t really compatible with the high frequency of our modulation.
So, we had the meeting, and even though we didn’t really find every bit of advice useful for the present time, we still learned a lot, and the suggestions we did implement have proven to be quite successful. This is all for this week, bye!