A portable device for measuring electrocardiographic signals, the device comprising: a first portion comprising at least two electrodes (1, 2); a second portion comprising at least three electrodes (3, 4, 5, 15); the first portion and the second portion being vertically spaced from one another; a controller configured to take: a first potential difference measurement using one of the electrodes (1, 2) of the first portion and one of the electrodes (3, 4, 5, 15) of the second portion; a second potential difference measurement using one other of the electrodes (1, 2) of the first portion and one other of the electrodes (3, 4, 5, 15) of the second portion; and a third potential difference measurement using one other of the electrodes (1, 2) of the first portion and one other of the electrodes (3, 4, 5, 15) of the second portion; wherein the controller is configured to simultaneously take the first, second and third potential difference measurements at three independent positions of a user's body; wherein the device is configured to be positioned such that the first portion of the device is located near a region proximal to a sinoatrial node of a heart of the user's body and the second portion is located near a region of an apex mitral area of the heart of the user's body; characterized in that a vertical distance between the at least two electrodes (1, 2) of the first portion and the at least three electrodes (3, 4, 5, 15) of the second portion is between 20mm and 80mm, the vertical distance being measured between a horizontal line intersecting the at least two electrodes (1, 2) of the first portion and a horizontal line intersecting at least a first electrode of the second portion; wherein a lateral distance between a middle point of the electrodes (1, 2) of the first portion and the first electrode of the second portion is between 20mm and 80mm; and wherein a lateral distance between the middle point of the electrodes (1, 2) of the first portion and a final electrode of the second portion is between 100mm and 250mm. a first portion comprising at least two electrodes (1, 2); a second portion comprising at least three electrodes (3, 4, 5, 15); the first portion and the second portion being vertically spaced from one another; a controller configured to take: a first potential difference measurement using one of the electrodes (1, 2) of the first portion and one of the electrodes (3, 4, 5, 15) of the second portion; a second potential difference measurement using one other of the electrodes (1, 2) of the first portion and one other of the electrodes (3, 4, 5, 15) of the second portion; and a third potential difference measurement using one other of the electrodes (1, 2) of the first portion and one other of the electrodes (3, 4, 5, 15) of the second portion; a first potential difference measurement using one of the electrodes (1, 2) of the first portion and one of the electrodes (3, 4, 5, 15) of the second portion; a second potential difference measurement using one other of the electrodes (1, 2) of the first portion and one other of the electrodes (3, 4, 5, 15) of the second portion; and a third potential difference measurement using one other of the electrodes (1, 2) of the first portion and one other of the electrodes (3, 4, 5, 15) of the second portion; wherein the controller is configured to simultaneously take the first, second and third potential difference measurements at three independent positions of a user's body; wherein the device is configured to be positioned such that the first portion of the device is located near a region proximal to a sinoatrial node of a heart of the user's body and the second portion is located near a region of an apex mitral area of the heart of the user's body; characterized in that a vertical distance between the at least two electrodes (1, 2) of the first portion and the at least three electrodes (3, 4, 5, 15) of the second portion is between 20mm and 80mm, the vertical distance being measured between a horizontal line intersecting the at least two electrodes (1, 2) of the first portion and a horizontal line intersecting at least a first electrode of the second portion; wherein a lateral distance between a middle point of the electrodes (1, 2) of the first portion and the first electrode of the second portion is between 20mm and 80mm; and wherein a lateral distance between the middle point of the electrodes (1, 2) of the first portion and a final electrode of the second portion is between 100mm and 250mm.