Comparison of multiple GPS navigation systems, signal and spectrum distribution 2021-08-11 whwireless GLONASS system The Russian GLONASS system is similar to the US GPS system, and is also a global positioning system by satellite. The system has 24 satellites distributed in 3 orbits with 8 satellites in each orbit and an orbital altitude of 19,100 km. Comparison of multiple GPS systems, signal and spectrum distribution Figure 1 GLONASS satellite constellation The GLONASS system also has two PRN codes, military and civilian, with positioning accuracy comparable to that of the GPS system. The C/A code rate is 511 kHz, the code length 511 and the code period 1 ms, while the P code rate is 5.11 MHz. The difference is that all GLONASS satellites use the same PRN code, which is differentiated by frequency division multiple access. The frequencies of the satellites are Comparison of multiple GPS navigation systems, signal and spectrum distribution k = 1, 2, 3 ......, 24 are the satellite numbers. The spectrum distribution of GPS and GLONASS signals in the L1 band is shown in Figure 2. Comparison of multiple GPS navigation systems, signal and spectrum distribution Figure 2 Spectrum distribution of GPS and GLONASS signals in the L1 band The GLONASS signal has a ground strength of -161 to -155.2 dBW. The initial satellite life of the GLONASS system was too short and the lack of funding due to the collapse of the Soviet Union meant that by July 2005 there were only 10 available satellites in the system. The GLONASS system has now also been modernised and upgraded with the launch of new long-life satellites and the addition of L2 C/A signals. Comparison of multiple GPS navigation systems, signal and spectrum distribution GALILEO The GALILEO system, launched by the European Union, consists of 30 satellites, evenly distributed over three orbits, with an altitude of 23,000 km, an orbital period of 14h 4min and an orbital inclination of 56°. and multi-service. The GALILEO system consists of 10 signals located in 4 frequency bands. (1) E5 band: frequency range 1164~1215 MHz, containing two bands E5a and E5b, each containing two signals, modulation mode AltBOC(15, 10), code rate 10.23 MHz, minimum signal reception power -155dBW. this band mainly provides Open Service (OS) and Safety-of-Life (SOL) services. (2) E6 band: The frequency range 1215-1300 MHz contains 3 signals, modulated by BPSK, with a code rate of 5.115 MHz and a minimum received power of -155 dBW. Service (CS). (3) E2-L1-E1: The frequency range of 1559-1591 MHz contains three signals, with the centre frequency of 1575.42 MHz being used for GPS compatibility. The E2 band covers 1559 to 1563 MHz and provides mainly public licensed services. Comparison of multiple GPS navigation systems, signal and spectrum distribution Figure 3 GALILEO signal spectrum distribution The spectrum distribution of GALILEO system signals is shown in Figure 3. Comparison of multiple GPS systems, signal and spectrum distr...

About 5G antenna OTA test method analysis and application Estimated 8 minutes to finish reading www.whwireless.com Test methods of existing antennas With the deepening of electromagnetic research and the development of electronic technology, the development and application of antennas have penetrated into many fields such as navigation, communication, electronic countermeasures and radar, etc. Multi-beam antennas can form multiple mutually independent transmit or receive beams simultaneously or in time through phased arrays to achieve flexible control of beam shape and rapid switching of beam direction. At present, the most widely used phased array antenna test methods are mainly three: far-field method, near-field method and tight field method. 1、Far field test scheme Far-field test is the most direct test method, when the test distance is far enough, the human wave in the receiving surface is close to the plane wave. The diagram below shows the far-field test system, where the part under test can be rotated 360° in the vertical and horizontal planes, and the test probe position is fixed and can be polarised and rotated. The test system can test the beam assignment directional map and EIRP (Effective Isotropic Radiated Power), EVM (Error Vector Magnitude), occupied bandwidth, EIS (Effective Isotropic Sensitive), and EIS (Effective Isotropic Sensitive) of the 5G base station antenna. Isotropic Sensitive, effective omnidirectional sensitivity) and other RF radiation indicators. 2、Tight field test programme The tight field test is a far-field test method, which can use a reflector or lens to convert the spherical wave from the feed source at the focal point into a plane wave, so as to achieve the far-field test in a limited physical space. The figure below shows a parabolic single reflector constrained field test system that can test the beam assignment direction map and EIRP, EVM, occupied bandwidth, ACLR (Adjacent Channel LeakagePower ration), EIS, ACS (Adjacent Channel Selectivity) of a 5G base station antenna. Channel Selectivity) and other RF radiation indicators. 3、Near-field test solution Multi-probe spherical near-field test solution Near-field test in the measured antenna radiation near-field area to collect the amplitude and phase information, and then through the near and far field conversion algorithm to collect data into the far field direction map. The multi-probe spherical near-field test system is shown in the diagram below, where a large number of probes are arranged along the circumference of the radiated near-field of the DUT, and the DUT only needs to be rotated by 180 degrees to capture data from the entire radiated sphere. The system is capable of testing the beam assignment direction of a 5G base station antenna in CW (Continuous Wave) mode.   Single probe near-field test system Single probe near-field testing is less efficient than multi-probe spherical near-field testing, but it is simpler and requires less space. The ...

Principles and functions of common antennas and passive components that engineers must master Estimated 6 minutes to finish reading www.whwireless.com 1. Antenna principle 1.1 Definition of antenna: Ø A device that can effectively radiate electromagnetic waves to a specific direction in space or can effectively receive electromagnetic waves from a specific direction in space. 1.2 The function of the antenna: Ø Energy conversion-the conversion between guided traveling waves and free space waves; Ø Directional radiation (receiving)-has a certain directionality. 1.3 Principle of antenna radiation 1.4 Antenna parameters u Radiation parameters ØHalf power beam width, front-to-back ratio; ØPolarization method, cross-polarization discrimination rate; ØDirectivity coefficient, antenna gain; ØMain lobe, side lobe, side lobe suppression, zero point filling, beam downtilt... u circuit parameters ØVoltage standing wave ratio VSWR, reflection coefficient Γ, return loss RL; ØInput impedance Zin, transmission loss TL; Ø Isolation degree Iso; ØPassive third-order intermodulation PIM3… u antenna side lobe u Horizontal beam width u Front-to-back ratio: Specify the ratio of the forward radiation power to the antenna and the backward radiation power within ±30° u The relationship between gain and antenna size and beam width Flatten the "tire", the more concentrated the signal, the higher the gain, the larger the antenna size, and the narrower the beam width; u Several key points of antenna gain: ØThe antenna is a passive device and cannot generate energy. Antenna gain is just the ability to effectively concentrate energy to radiate or receive electromagnetic waves in a specific direction. Ø The gain of the antenna is produced by the superposition of the vibrator. The higher the gain, the longer the antenna length. The gain is increased by 3dB and the volume is doubled. ØThe higher the antenna gain, the better the directivity, the more concentrated the energy, and the narrower the lobe. 1.5 Radiation parameters u Polarization: Refers to the trajectory or changing state of the electric field vector in space. 1.6 Circuit parameters u return loss In this example, the return loss is 10log(10/0.5) = 13dB VSWR (Standing Wave Ratio) is another measure of this phenomenon u Isolation: It is the ratio of the signal received by a certain polarization of another polarization u Passive Intermodulation (PIM): When two frequencies f1 and f2 are input to the antenna, due to the nonlinear effect, the signal radiated by the antenna includes other frequencies in addition to frequencies f1 and f2, such as 2f1-f2 and 2f2-f1 (3rd order).

What does antenna interface mean? Estimated 2 minutes to finish reading You will often see the word antenna at the interface of some home electronic devices, this word actually means antenna, so its corresponding interface is actually the antenna interface, which is specifically used to connect the antenna port. antenna interface is a round antenna interface, antenna interface is an interface end of wireless devices, the antenna of the wireless device itself has a certain distance limit. When the distance beyond this limit, it is necessary to enhance the wireless signal through these external antennas to achieve the purpose of extending the transmission distance. There are three concepts involved. First, the frequency range it refers to the antenna work frequency band, this parameter determines which wireless standard it applies to wireless devices. Second, the gain value of this parameter indicates the antenna power amplification, the larger the value indicates that the signal amplification is larger, that is to say, when the gain value is larger, the stronger the signal, the better the transmission quality. Third, the antenna interface is mainly for wireless equipment that can be disassembled and external antenna, for different interfaces to correctly match the corresponding antenna, to increase the signal and extend the distance of the function. www.whwireless.com