This paper presents a technological device that is able to estimate gait velocity in non-controlled conditions, specifically at home. Based on a Doppler sensor, it provides an instantaneous signal of velocity, hence an estimation of the average velocity on a short distance (3 m). Comparison with the results produced by usual clinical tests (time measured manually on 4.5 m or 10 m) shows an excellent correlation (R
>0.93), even though signal processing is achieved in a rudimentary manner. In addition, instantaneous recordings open the way towards extraction of other gait features like gait regularity and quality. Such a device can be used to assess frailty and risk of fall in the elderly in ecological conditions.