Measurement campaign in PLOCAN test tank
The first step in the UNDERWORLD project is task 1: Channel Characterization. It consists on measuring, defining and characterizing the underwater channel, in order to find out its behavior for sure, since at the moment there is no standardized model for this type of communications. For this reason, it is required to carry out measurement campaigns and data analysis.
Hitherto, the first measurement campaign, in PLOCAN (Oceanic Platform of the Canary Islands) test tank in Taliarte, has been successfully accomplished in January 2015. To do so, some antennae prototypes and some predictions of attenuation have been developed in order to compare theoretical results with the measurements obtained in a controlled scenario. The correctness of the measurement processes has also been checked. Fortunately, the results have been quite similar and these will be published in a few weeks.
The first campaign took place in a controlled scenario, the PLOCAN facilities in Taliarte (Gran Canaria, Canary Islands, Spain). Its basic objective was to gain experience in the measurement process and to verify the basic behavior of the developed antennae A test tank with salt water emulated some of the conditions which will be used in real sea conditions. The parameters of interest in this first series of measurements (static) are: the signal attenuation (the amount of power lost in the medium), the channel impulse response (its behavior) and the delays between the transmitted signal and the received signal (the time that the signal takes to reach the receiver).
The considered measurements set can be seen in the figure below, in which the receiving and the transmitting antennae are located underwater (two single dipoles), a signal is transmitted through the generator and the power reaching the receiver is measured using the spectrum analyzer. The procedure is repeated as both the signal frequency and the distance between antennae are modified. The other parameters are measured similarly but using an oscilloscope, in order to check the transmitted and the received signals.
These measurements made possible to calculate the attenuation of the signal depending on the selected frequency and the distance between transmitter and receiver, which varies between about 60 and 90 dB. As a result, several graphs were obtained to compare the theoretical results with the obtained results.