The first step in transmitting radio-frequency signals through space is to create a pure carrier at the transmitter. This electrical wave must be of stable, unvarying amplitude, frequency and phase. A quartz crystal oscillator frequently serves the purpose. Information can be conveyed when the carrier is modulated. At the receiver, the carrier is demodulated, separating out an audio or another signal.
It is also possible, using the common super-heterodyne principle, to alter the carrier frequency. The idea uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original radio carrier frequency. For each frequency that is broadcast, a different beat frequency is required if a consistent IF is to result.
HDMI Encoder Modulator,16in1 Digital Headend, HD RF Modulator at SOUKA https://www.soukacatv.com/.
To this end, in the early years of radio, broadcasters sent a heterodyne frequency that they generated alongside the primary broadcast carrier. Soon it was found to be more efficient to generate the beat frequency locally, i.e. at the receiver, and that is how it is done currently. That is why the traditional variable capacitor was two-gang, with twin sets of plates on the same shaft. As different stations were tuned in, the receiver created the appropriate beat frequency. Today essentially the same process takes place in an electronic tuner.
In various modulation schemes, any readable alteration of the carrier’s signal qualities can suffice to carry information. The usual parameters are amplitude, frequency and phase. These can be used singly or in combination, and they are applicable to both analog and digital modulation. A previous article discussed analog modulation. Now we’ll take a closer look at digital modulation.
Digital modulation modifies an analog carrier signal with another discrete signal. Digital modulation methods can be considered digital-to-analog conversion and the corresponding demodulation or detection analog-to-digital conversion. Digital transmission has significant advantages over its analog counterpart. For one thing, it is relatively noise free. If noise is introduced, it originates outside of the digital transmission proper, that is in the pre-modulation and post-demodulation zones. Furthermore, digital modulation makes better use of bandwidth. As there is increasing competition for limited spectrum, this characteristic assumes ever-greater importance.
The standard method for representing digital modulation is by means of a polar diagram. This display represents amplitude and phase in a single graphic. The length of a vector arrow corresponds to the magnitude and the angle of that line with respect to a horizontal line connecting the origin to the zero-degree point on the circle represents the phase angle that is invoked in the modulation process. Amplitude and phase modulation are used in concert to convey the digital information. Any instantaneous value of the digital signal can be represented by a point within the polar diagram.
Digital modulation is generally represented by making reference to I and Q. The I axis is the zero-degree horizontal reference line on the polar diagram. The Q axis is the vertical line that represents a 90° polarization angle.
The vector in the polar diagram represents an RF carrier with an output power represented by the length of the vector and a certain phase angle represented by the angle with the horizontal axis. If the RF carrier has a constant output power, it could be represented on the polar diagram as a vector with a constant length (amplitude) which follows the trajectory of a circle.
Phase and magnitude fluctuations taken together convey the digital information. The result is expressed in terms of I and Q where the signal vector’s projection onto the I axis lies on the zero degrees reference (thus called the In-phase component) and the projection onto the Q axis lies on the 90° shifted phase reference (Quadrature component). The phase and amplitude information of the signal, often called S(t), with a carrier frequency w is then expressed in terms of I and Q by the equation:
S(t) = I(t)cos(w)+Q(t)sin(w)
Recall from algebra that the sine and cosine are 90° out of phase with each other. That relationship leads to the basic topology of a digital modulator or demodulator.
For a transmitter, I and Q data are applied at the inputs of two different mixers driven by a local oscillator (or RF carrier) frequency of w. The local oscillator is shifted by 90° before it drives the mixer for the Q data. The mixers form the multiplication of the terms given in the equation.
Nearly every digital modulator or demodulator uses this principle. Data to be transmitted gets coded into I/Q pairs before being fed to an I/Q modulator. The necessary circuitry can be built with digital logic or programmed in a DSP. Moreover, at a cost of greater complexity, the I-Q modulation scheme is more bandwidth-efficient than analog modulation.
Established in 2000, the Soukacatv.com (DSW) main products are modulators both in digital and analog modulators, amplifier and combiner. We are the leading communication supplier in manufacturing the headend system in China. Our 16 in 1 and 24 in 1 now are the most popular products all over the world. For more, please access to https://www.soukacatv.com/.
Source: testandmeasurementtips
【The Combination of SOUKA Digital Modulator from Soukacatv.com】About SOUKA SKD271X digital modulator supports DVB-T and ISDB-T.
The SKD271X digital modulator either works with the SKD-M1 chassis or works alone with SKD-F2D power cable.For more,please access to https://www.soukacatv.com/the-combination-of-souka-digital-modulator_n25Dingshengwei Electronics Co., Ltd(DSW) is dedicated to design, manufacture and sales of CATV analog & digital headend with our brand name SOUKA.
DSW obtained ISO9001:2008 certificate authorized by CQC.
We have 100 in-house skillful workers, which ensures the punctual delivery date.
And a professional engineer team made up of 10 senior RF engineers and 6 IT engineers to fulfil precise management over all projects honored by our customers.As one of the most reliable suppliers in this field, we continually spare no efforts in developing DSW into a world recognized brand with trustworthy and solid reputation.
DSW sincerely invites you to enjoy the fascinating experience of modern technology and excellent customer service provided for you by our professional staff.
The Magnetic Linear Encoder market was valued at Million US$ in 2018 and is projected to reach Million US$ by 2025, at a CAGR of during the forecast period.
In this study, 2018 has been considered as the base year and 2019 to 2025 as the forecast period to estimate the market size for Magnetic Linear Encoder.This report presents the worldwide Magnetic Linear Encoder market size (value, production and consumption), splits the breakdown (data status 2014–2019 and forecast to 2025), by manufacturers, region, type and application.Download FREE Sample of this Report @ https://www.grandresearchstore.com/report-sample/global-magnetic-linear-encoder-2025-767This study also analyzes the market status, market share, growth rate, future trends, market drivers, opportunities and challenges, risks and entry barriers, sales channels, distributors and Porter’s Five Forces Analysis.The following manufacturers are covered in this report:Baumer GroupElectronica Mechatronic SystemsBEI SensorsATEK Sensor TechnologiesTreothamMicromech LtdVelmex IncMagnetic Linear Encoder Breakdown Data by TypeVoltage Output TypeOpen Collector Output TypePush-pull Complementary Output typeMagnetic Linear Encoder Breakdown Data by ApplicationCMMLaser ScannersCallipersOthersMagnetic Linear Encoder Production by RegionUnited StatesEuropeChinaJapanSouth KoreaOther RegionsMagnetic Linear Encoder Consumption by RegionNorth AmericaUnited StatesCanadaMexicoAsia-PacificChinaIndiaJapanSouth KoreaAustraliaIndonesiaMalaysiaPhilippinesThailandVietnamEuropeGermanyFranceUKItalyRussiaRest of EuropeCentral & South AmericaBrazilRest of South AmericaMiddle East & AfricaGCC CountriesTurkeyEgyptSouth AfricaRest of Middle East & AfricaThe study objectives are:To analyze and research the global Magnetic Linear Encoder status and future forecast?involving, production, revenue, consumption, historical and forecast.To present the key Magnetic Linear Encoder manufacturers, production, revenue, market share, and recent development.To split the breakdown data by regions, type, manufacturers and applications.To analyze the global and key regions market potential and advantage, opportunity and challenge, restraints and risks.To identify significant trends, drivers, influence factors in global and regions.To analyze competitive developments such as expansions, agreements, new product launches, and acquisitions in the market.In this study, the years considered to estimate the market size of Magnetic Linear Encoder :History Year: 2014–2018Base Year: 2018Estimated Year: 2019Forecast Year: 2019–2025This report includes the estimation of market size for value (million USD) and volume (K Units).
Both top-down and bottom-up approaches have been used to estimate and validate the market size of Magnetic Linear Encoder market, to estimate the size of various other dependent submarkets in the overall market.
Key players in the market have been identified through secondary research, and their market shares have been determined through primary and secondary research.
All percentage shares, splits, and breakdowns have been determined using secondary sources and verified primary sources.For the data information by region, company, type and application, 2018 is considered as the base year.
Whenever data information was unavailable for the base year, the prior year has been considered.Get the Complete Report & TOC @ https://www.grandresearchstore.com/semiconductor-and-electronics/global-magnetic-linear-encoder-2025-767Table of content1 Study Coverage1.1 Magnetic Linear Encoder Product1.2 Key Market Segments in This Study1.3 Key Manufacturers Covered1.4 Market by Type1.4.1 Global Magnetic Linear Encoder Market Size Growth Rate by Type1.4.2 Voltage Output Type1.4.3 Open Collector Output Type1.4.4 Push-pull Complementary Output type1.5 Market by Application1.5.1 Global Magnetic Linear Encoder Market Size Growth Rate by Application1.5.2 CMM1.5.3 Laser Scanners1.5.4 Callipers1.5.5 Others1.6 Study Objectives1.7 Years Considered2 Executive Summary2.1 Global Magnetic Linear Encoder Market Size2.1.1 Global Magnetic Linear Encoder Revenue 2014–20252.1.2 Global Magnetic Linear Encoder Production 2014–20252.2 Magnetic Linear Encoder Growth Rate (CAGR) 2019–20252.3 Analysis of Competitive Landscape2.3.1 Manufacturers Market Concentration Ratio (CR5 and HHI)2.3.2 Key Magnetic Linear Encoder Manufacturers2.3.2.1 Magnetic Linear Encoder Manufacturing Base Distribution, Headquarters2.3.2.2 Manufacturers Magnetic Linear Encoder Product Offered2.3.2.3 Date of Manufacturers Enter into Magnetic Linear Encoder Market2.4 Key Trends for Magnetic Linear Encoder Markets & ProductsCONTACT US:276 5th Avenue, New York , NY 10001,United StatesInternational: (+1) 646 781 7170 / +91 8087042414Email: [email protected] Us On linkedin :- https://www.linkedin.com/company/grand-research-store/
