A system and a method are provided for deriving elctrocardiographic (ECG] signals from a subject. The system includes an ECG apparatus configured to acquire ECG signals from the subject through a plurality of ECG leads, wherein the plurality of ECG leads includes lead groups that are traditionally presumed to be orthogonal. A processor or method are provided to analyze combinations of ECG leads from the plurality of ECG leads to determine a spectral signal-to-noise ratio (SNR] for each combination of ECG leads and select a combination of ECG leads that provides a desirable spectral SNR. The ECG signals derived from the combination of ECG leads selected as providing the desirable spectral SNR may be provided or may be used to derive and report respiratory rate information about the subject.
