Alternatively to the classical altimeters, transmitted pulses in HR mode are groupped in bursts. The pulses within a burst have to be coherent. Thus, the PRI (Pulse Repetition Interval) has to be chosen accordingly.
Moreover, in order to exploit the concept of Delay-Doppler altimetry, these bursts have to be spaced enough so that the pulses are incoherent from burst to burst and they can be averaged later on to improve the SNR. Then another parameter comes up: the Burst Repetition Interval (BRI).
The following pictures show the transmission patterns from different Delay-Doppler altimeters.
Sentinel-3 transmission pattern. Note that bursts include 2 C-band pulses here. These are used for ionospheric corrections. Credit: ESA
Sentinel-6 transmission pattern. Observe that no bursts are present and calibration pulses are also in the same transmission pattern as the Ku- and C-band pulses. Credit: ESA