1. A computer-based method for positioning an endovascular device in or near the heart using electrocardiogram (ECG) signals, comprising: receiving an endovascular ECG signal associated with an endovascular device, including many waveforms, each of which has at least a P wave component； endovascular ECG signal for a plurality of predetermined time periods for calculating the P wave amplitude and spectral power for each predetermined time period； dividing the maximum amplitude of the P wave from the multiple amplitudes of the P wave and the corresponding maximum spectral power from the set of spectral powers； associating the maximum amplitude of the P wave and maximum spectral power with a predetermined location in or near the heart； calculating the location of the endovascular device for each predetermined time period based on the ratio of the amplitude of the P wave to the maximum amplitude of the P wave and the ratio of spectral power to the maximum spectral osnosti； and displaying to the user the location of the endovascular device. 2. The method according to claim 1, wherein the amplitude of the P wave is the amplitude of the oscillation and the maximum amplitude of the P wave is the amplitude of the oscillation. The method of claim 2, wherein said ECG signal processing includes determining a polarity for each amplitude of the P wave, and said determining the location of the endovascular device is also based on the polarity of the P wave for each predetermined time period. The method of claim 3, wherein1. Компьютерный способ позиционирования эндоваскулярного устройства в сердце или рядом с ним с использованием сигналов электрокардиограммы (ЭКГ), включающий:прием эндоваскулярного сигнала ЭКГ, ассоциированного с эндоваскулярным устройством, включающего множество форм колебаний, каждая из которых имеет по меньшей мере компонент зубца P；обработку эндоваскулярного сигнала ЭКГ в течение множества заранее заданных периодов времени для вычисления амплитуды зубца P и спе
