Biometric recognition is becoming part of applications where the privacy of the information is crucial, as in the health care field. In this paper, we present a biometric recognition system based on the Electrocardiographic signals (ECG). Our approach builds on a state of the art recognition method which extracts information from the frequency domain. Due to limited bandwidth of certain acquisition systems we propose a new method capable of increasing the spectral resolution of low bandwidth ECG signals. Preliminary results show that the proposed algorithm reveals a superior identification rate and lower equal error rate when compared to an previous approaches.