The Sphygmocor system purports to be able to assess ascending aortic blood pressure using a transfer function. It has been shown to be accurate when data obtained invasively are used, but has not been tested prospectively using data obtained non-invasively.
Davies, J. I., Band, M. M., Pringle, S., Ogston, S., & Struthers, A. D. (2003). Peripheral blood pressure measurement is as good as applanation tonometry at predicting ascending aortic blood pressure. Journal of Hypertension, 21(3), 571-6. https://doi.org/10.1097/00004872-200303000-00023