A rock drilling rig comprising: a movable carrier; at least one drilling boom; a drilling unit at a distal end part of the drilling boom, wherein the drilling unit comprises a feed beam and a rock drilling machine supported movably on the feed beam; and the drilling unit is provided with sensing means for providing sensing data during rock drilling; wherein the rock drilling machine, comprises: a body comprising - an impact device comprising an elongated impact element configured to generate impact pulses directed to a rotation element; - a rotation device; and - a rotation element configured to be rotated around its longitudinal axis by means of the rotation device, and which rotation element is located at a front end portion of the body; and a drilling tool provided with a central flushing passage and connected to the rotation element; characterized in that the rock drilling machine further comprises: at least one sensing device; a feed passage; a sensing cord, which is an elongated bendable element configured to be inserted through the feed passage to the central flushing passage of the drilling tool; the mentioned feed passage is configured to pass through the impact element of the impact device; and wherein the sensing device is in connection with the sensing cord. a movable carrier; at least one drilling boom; a drilling unit at a distal end part of the drilling boom, wherein the drilling unit comprises a feed beam and a rock drilling machine supported movably on the feed beam; and the drilling unit is provided with sensing means for providing sensing data during rock drilling; wherein the rock drilling machine, comprises: a body comprising - an impact device comprising an elongated impact element configured to generate impact pulses directed to a rotation element; - a rotation device; and - a rotation element configured to be rotated around its longitudinal axis by means of the rotation device, and which rotation element is located at a front end portion of the body; and a drilling tool provided with a central flushing passage and connected to the rotation element; characterized in that the rock drilling machine further comprises: at least one sensing device; a feed passage; a sensing cord, which is an elongated bendable element configured to be inserted through the feed passage to the central flushing passage of the drilling tool; the mentioned feed passage is configured to pass through the impact element of the impact device; and wherein the sensing device is in connection with the sensing cord. a body comprising - an impact device comprising an elongated impact element configured to generate impact pulses directed to a rotation element; - a rotation device; and - a rotation element configured to be rotated around its longitudinal axis by means of the rotation device, and which rotation element is located at a front end portion of the body; and - an impact device comprising an elongated impact element configured to generate impact pulses directed to a rotation element; - a rotation device; and - a rotation element configured to be rotated around its longitudinal axis by means of the rotation device, and which rotation element is located at a front end portion of the body; and a drilling tool provided with a central flushing passage and connected to the rotation element; characterized in that the rock drilling machine further comprises: at least one sensing device; a feed passage; a sensing cord, which is an elongated bendable element configured to be inserted through the feed passage to the central flushing passage of the drilling tool; the mentioned feed passage is configured to pass through the impact element of the impact device; and wherein the sensing device is in connection with the sensing cord. at least one sensing device; a feed passage; a sensing cord, which is an elongated bendable element configured to be inserted through the feed passage to the central flushing passage of the drilling tool; the mentioned feed passage is configured to pass through the impact element of the impact device; and wherein the sensing device is in connection with the sensing cord.