ECG And PPG Heart Rate Monitoring Compared

What PPG actually measures

A PPG sensor shines light into the skin and measures how much comes back. Blood volume changes with each heartbeat, so the reflected signal rises and falls, and the interval between peaks gives a heart rate. Every watch in this catalogue carries one: PAH8007 on the 1.1 inch trackers, LC10A on the 1.7 inch band, HX3605 on the 1.85 inch calling watch, HRS3300 on T32S, VC32S on UQ33 and PAH 8009 on the 4G models.

What an ECG front end measures

An ECG front end measures the electrical activity of the heart through electrodes in contact with the skin. It is a different physical quantity. On the Medical Grade ECG HRV watch that front end is a Maxim Max86176 sampling at 512Hz, with a Goodix 5515 host. Sampling rate matters because the features a clinician looks for in a trace are short.

Where the difference shows up

PPG gives a continuous heart rate and, with enough processing, heart rate variability. It does not produce a waveform a cardiologist can read. An ECG front end does. That is why the ECG model in this range is the one quoted into telehealth programmes and why the trackers are not.

Certification is a separate question

A capable ECG chip does not make a certified medical device. The source material for this catalogue describes CFDA and FDA medical certification as being sought for that ECG platform. Pending is not granted, and we publish it as pending. Any supplier who blurs that distinction is creating a problem for the buyer, not solving one.

Choosing between them

If the requirement is activity, sleep, recovery and trend data, a PPG device is the right tool and the cheaper one. If the requirement is a cardiac waveform that someone will review, specify the ECG platform and read the certification status carefully.