Abstract: A method and device for monitoring down-the-hole percussion drilling. A down-the-hole hammer is supplied with percussion and flushing fluid flow. The down-the-hole hammer is subjected to rotational force and to feed force. Percussion frequency or a related frequency of the down-the-hole hammer is sensed. A representation of a spread thereof is created so as to produce a response to an adjustment of at least one drilling parameter as a change of width of the spread.

Abstract: A bottom-hole assembly (202), BHA, for drilling a borehole (204, 301) in an earth formation (208, 300), comprising a percussion drill bit (208), a percussion mechanism adapted to strike the drill bit (208), at least one sensor (226, 228, 230, 232, 234) for measuring a physical quantity and converting it into an electrical signal, and converting means (237) for converting the electrical signal into a digital signal, and a method for transmitting data from such a bottom-hole assembly (202) positioned in a borehole (204, 301), the bottom-hole assembly (202) and the method being characterized by encoding the digital signal by controlling the percussion mechanism and time periods between two impacts delivered by the percussion mechanism on the drill bit (208) during drilling, and transmitting the encoded digital signal by waves generated by the impacts delivered by the percussion mechanism on the drill bit (208). A system which comprises said bottom-hole assembly (202).

Abstract: A method and device for monitoring down-the-hole percussion drilling. A down-the-hole hammer is supplied with percussion and flushing fluid flow. The down-the-hole hammer is subjected to rotational force and to feed force. Percussion frequency or a related frequency of the down-the-hole hammer is sensed. A representation of a spread thereof is created so as to produce a response to an adjustment of at least one drilling parameter as a change of width of the spread.