Such a system is particularly intended for the security of vulnerable persons living alone, such as for instance elderly persons. In his or her living environment, everyone runs the risk of having an accident whereby one may become immobilized. Such an accident may in itself be relatively innocent: for instance, one may slip in the bathroom or trip in the living room. The consequences, however, may be serious: one may for instance break a leg or hip, so that one cannot move anymore. At that moment, one is dependent on assistance from other people; persons living alone should then try to draw the attention of their neighbors, which may take a long time if one is no longer capable of operating a telephone either.
It will be understood that such a risk of injury is particularly present with elderly people. It may even be the case that elderly people no longer dare to live alone, and for that reason move to an old people's home, while this would in itself not be necessary.
An alarm system of the above-mentioned type solves such problems, because it offers the person in question a possibility of summoning help, for whatever reason, from the place where that person is located at that moment. The only thing that this person should do for that purpose is operate the alarm switch of his carrier unit.
In response to the operation of the alarm switch, the carrier unit generates a signal which is wirelessly transmitted to the base unit (radio transmission). The base unit is connected with a communication network, for instance the public telephone network. In response to the received signal, the base unit sets up a connection with the alarm monitoring station. This alarm monitoring station for instance consists of a central reporting room of an alerting organization or a house, of family or acquaintances of the user of the alarm system, with a communication network connection. Depending on the circumstances and the advancement of the system used, different reactions are now possible. Generally, an operator is present at the alarm monitoring station, who sends assistance to the user who raised alarm. This operator is for instance an assistant of the alerting organization or family or an acquaintance of the user of the alarm system. In this connection, it is desired that communication be possible between the operator and the user, on the one hand to comfort the user and to assure him that his message has been received, on the other hand to enable establishing the reason of the alarm call. Depending on that reason, the operator can send specialized assistance, for instance a doctor or even an ambulance.
Thus, an alarm system offers the important advantage that in the event of an calamity, assistance can be summoned promptly at all times. A further important advantage precisely resides in knowing that assistance can be summoned promptly if a calamity occurs, and that very knowledge is a reassurance, even if the person in question never has to employ the emergency call facility. An important consequence is that elderly persons can continue living on their own for a longer time and also feel safe in doing so, which contributes to their joy of life.
In the known system, this communication takes place by means of one or more microphones and loudspeakers which are positioned in the user's house and connected to the base unit.
A number of drawbacks are associated herewith. Because, from the nature of things, the number of microphones is limited, the audibility of the user to the operator depends on the place where the user is located. Under certain circumstances, it is then even possible that the operator cannot hear the user. This situation occurs in particular if the user is not located in a space wherein a microphone of the alarm system is provided, or if the user, as a consequence of the emergency situation which formed the cause for calling in help, is unable to speak loudly. In order to avoid this risk as much as possible, the installation of the microphones should be handled with great consideration.