As a new type of intelligent stethoscope, underground pipeline detector is used to survey underground pipelines. It is composed of transmitter, receiver and accessories. It is mainly used for underground pipeline positioning, buried depth measurement and long-distance tracking, as well as pipeline insulation fault point measurement and search. The equipment adopts multi coil electromagnetic technology, which greatly improves its depth determination accuracy and target pipeline identification ability. It can accurately track and locate the target pipeline even in the area with dense and complex pipelines. However, due to the complexity and diversity of underground pipelines, a better method is to combine various technical methods for general survey. The common site conditions in the operation of underground pipeline detector are as follows: 1. Track from the joint or handover box. Before the cable applies the transmitter signal, the common connector on the cable needs to be removed to track the target pipe. If all cables are to be tracked from the junction box, the transmitter can work in an inductive manner, placed on one side of the junction box and in line with the cable to be tracked. 2. Long distance tracking cable. In order for the transmitter signal to transmit a sufficient distance, it is necessary to remove the grounding connection of the cable. When the joint or joint is grounded for safety or lightning protection, surge arrester (anti overload) can be used to replace the grounding of the joint or joint, so as to protect the cable and make uninterrupted positioning possible. 3. Is the connector spike. Most cable connectors or connectors will generate spike pulse when the receiver responds. Working experience and understanding the local situation will help the operator to judge whether the spike pulse indicates that there is a connector box. 4. It's a metal guardrail. The cable is usually buried directly under the road outside the road metal guardrail, and the signal is combined with the continuous metal guardrail. The metal guardrail is close to the antenna at the lower part of the receiver, which is difficult to track. When it comes to the receiver, this difficulty can be overcome by making the internal antenna at the lower end flat with the metal guardrail. 5. Street lighting. Generally, the metal column of street lamp and the metal shielding layer of lighting cable are connected with the metal column. At this time, the transmitter signal can be connected to the metal column of street lamp. If the cement lamp post - unless the lighting cable can be connected to the maintenance rack and grounded, the transmitter signal needs to be connected to the metal shielding of the lighting cable. Knowing the relevant location and depth of lighting cables (and other street facilities on the same lighting system) can help track lighting cables. A connection point may apply signals to a large area of cables. It is also feasible to use street lamp posts to apply signals to other power cables, but the signal may be weak because the signal may have been transmitted for a long distance before returning to the substation and can flow out of the system again. At this time, the transmitter can increase the output power mode and increase the output power. This method can locate cables that are difficult to apply signals or inconvenient. For cables coming down from wooden poles, cement poles or lighting columns, the transmitter can be placed in sensing mode to apply a signal by making a right angle to the ground on the pole.