Contrastive learning has become popular for unsupervised representation learning, but optimal augmentation strategies for time series classification are not well-studied.
Existing time-domain augmentation methods are not specific to time series, leading to potential distortion of data with mismatched patterns.
A new perspective from the frequency domain is introduced, proposing FreRA for time series contrastive learning on classification tasks.
FreRA separates critical and unimportant frequency components, enhancing contrastive representation learning and generalization across diverse datasets.