Detection of paroxysmal atrial fibrillation requires continuous cardiovascular monitoring due to its episodic nature. Such monitoring is impractical with electrocardiogram Holter monitors, which are the currently employed for ambulatory cardiovascular monitoring, but are cumbersome for prolonged use. This thesis studies monitoring using photoplethysmography (PPG) devices, which may be embedded into wristband devices which can be easily worn continuously. However, the quality of wrist-based PPG is highly variable, and is subject to artifacts from motion and other interferences. The goal of this thesis is to evaluate the signal quality obtained from wrist-based PPG when used in an ambulatory setting. Ambulatory data is collected over a 24-hour period for 10 elderly, and 16 non-elderly participants. Visual assessment is used as the gold standard for PPG signal quality, with Fleiss's Kappa being used to evaluate the agreement between raters. With this gold standard, 5 classifiers are evaluated using a modified 13-fold cross-validation approach.