What is the function of GNSS receiver

The GNSS receiver receives the signals transmitted by the GNSS satellite through the antenna. The signals generated by the GNSS satellite include ranging code, carrier and navigation message.

The ranging code and carrier are used to measure the distance from the satellite to the receiver, and the navigation message is used to calculate the satellite position.GNSS receiver consists of antenna unit and receiving unit.

The first:Antenna unit

The antenna is composed of receiver antenna and preamplifier.

The function of the antenna is to convert the extremely weak electromagnetic wave energy of the GPS satellite signal into the corresponding current, while the preamplifier is to amplify the GPS signal current to facilitate the receiver to track, process and measure the signal. There are the following requirements for the antenna part:

1. The antenna and preamplifier shall be sealed as a whole to ensure their normal operation and reduce signal loss.

2. Be able to receive satellite signals from the hemisphere above the antenna without dead angle, so as to ensure that satellite signals from any direction of the sky can be received.

3. Measures shall be taken to protect and shield multipath effects.Keep the antenna phase center height stable and consistent with its geometric center as much as possible.

The second:Receiving unit.

The receiving unit of GPS signal receiver is mainly composed of signal channel unit, storage unit, calculation and display control unit and power lamp.

1. Signal channel

The signal channel is the core part of the receiving unit, which is composed of hardware and software. There are three different types of signal channels: square type, code phase type and correlation type.

2. Storage unit

The GPS signal receiver is equipped with a memory to store the interpreted GPS satellite ephemeris, pseudorange observation, carrier phase observation and various information data.

The calculation and display control unit is composed of microprocessor and display. The microprocessor is the control system of the GPS signal receiver, and all work of the GPS receiver is automatically completed under the instruction control of the microprocessor. Its main tasks as below:

1） Perform self-inspection on each channel immediately after the receiver is turned on, display the self-inspection results, measure, correct and store the delay value of each channel.

2） According to the data code output by the tracking loop of each channel, the GPS satellite ephemeris is interpreted, and the three-dimensional geocentric coordinates of the station (WGS-84 coordinate          system) are calculated according to the propagation time of the measured GPS signal to the receiver antenna, and the station coordinates are continuously updated according to the preset position update rate.

3） According to the measured approximate coordinates of the station and the GPS satellite ephemeris, the rise and fall time, azimuth and altitude angle of all satellites in orbit are calculated.

4） Record the station information entered by the user, such as station name, antenna height, meteorological parameters, etc.

5） The navigation parameters are calculated according to the preset waypoint coordinates and the measured approximate coordinates of the survey station, such as yaw distance, yaw angle, navigation speed, etc.

3. Power supply

The power supply of GPS signal receiver is generally battery, and lithium battery is generally equipped in the machine to supply power to RAM memory to prevent data loss after shutdown.

At present, the receiver is widely used in static displacement measurement such as mountain slope deformation monitoring, reservoir dam deformation monitoring, bridge deformation monitoring, etc. It continuously receives the original data of Beidou and GLONASS, and calculates an accurate geodetic coordinate through the post-processing software. When the GNSS antenna fixed on the surface of the structure is displaced, the actual deformation of the horizontal displacement and vertical displacement of the GNSS antenna fixed position can be accurately calculated through the comparison of the geodetic coordinates calculated by the post-processing software.

The X200 is a highly integrated receiver that can be connected to external sensors.Support mobile station and base station two working modes, support MQTT, NTRIP and TCP communication.The product is mainly used in geological disaster monitoring, deformation monitoring and other fields, high precision, high reliability.