Abstract
This paper deals with the information transmission characteristics of a two-dimensional electrocutaneous communication method using magnitude and frequency simultaneously. Firstly, the channel capacity of a two-dimensional electrocutaneous communication system is discussed. Secondly, the maximum information transmission rate is estimated from a category detection test. Finally, the reaction time, the time between the presentation of a two-dimensional electrocutaneous stimulus and a detectable response to it is measured and the maximum information transmission rate per second is calculated.
The following results are obtained; (1) The channel capacity of the two-dimensional electrocutaneous communication system is the summation of the channel capacities of both the magnitude dimension in a minimum frequency level and the frequency dimension in a minimum magnitude level. Its value ranges from 5.6 to 6.0 [bit/symbol] for four subjects. (2) The maximum information transmission rate estimated from the category detection test is 2.7-3.2 [bit/symbol] for three subjects. It is larger than the individual one-dimensional information transmission rate, but not more than the sum of the both. Especially, when the frequency and the magnitude dimensional stimuli are presented simultaneously, the information rate transmitted only through the magnitude dimension has a tendency to decrease due to the interaction between the two dimensions. (3) The reaction time of the two-dimensional category detection test is 300-970[ms] for Nm=2∼4, Nf=2∼4, where Nm and Nf indicate the numbers of categories of magnitude and frequency, respectively. On the basis of the above results, the upper limit of the presented number of the two-dimensional categories is a paired Nm=3, Nf=3, which can be more advantageous for the simultaneous presentation of two-dimensional stimuli from the standpoint of increasing the information transmisson rate per second than for the sequential presentation of them. For Nm=2∼3, Nf=2∼3 information transmission rate per second is found to be 4.5 [bit/symbol] to 6.4 [bit/symbol].
