Modulation is one type of process used to change the properties of a periodic signal which is known as carrier signal with a modulating signal that normally contains data to be transferred. This technique is frequently used in electronics as well as telecommunications. In the 20th century, most of the radio systems used AM or FM for broadcasting. This article discusses how the data can be communicated in digital form by modulating a carrier waveform. Even though, this method is called as DM (Digital Modulation). Generally, it involves AM (or) FM (or) PM. Therefore digital modulation must be observed the three modulation techniques how they communicating the information in the form of bits. In the rule, the same types of modulator otherwise demodulator can be used as these modulations are used to transmit analog pattern.

HDMI Encoder Modulator, 16in1 Digital Headend, HD RF Modulator at Soukacatv.com

What is Digital Modulation?

Types of Digital Modulation

There are several kinds of digital modulation techniques are available based on the requirement which includes the following.

ASK or Amplitude shift Key

FSK or Frequency shift key

PSK or Phase shift key


1) ASK (Amplitude Shift Keying)

In amplitude shift keying, once the instant amplitude of the carrier signal is changed in quantity toward m(t) message signal. For instance, if we have the modulated carrier (m(t) coswct) then the carrier signal will be coswct. Because the data is an ON/OFF signal, and the output is also an ON/OFF signal wherever the carrier is there when data is 1, as well as the carrier, is not present when data is 0. Therefore this modulation scheme is called as OOK or on/off keying (OOK) otherwise amplitude shift keying or ASK. The applications of ASK mainly include IR remote controls and fiber optic transmitter & receiver.

2) FSK (Frequency Shift Keying)

In frequency shift keying, when the immediate frequency of the carrier signal is changed then the information will be transmitted. In this type of modulation, carrier signal has two pre-defined frequencies namely wc1, and wc2. Whenever the data bit is ‘1’ then the carrier signal by wc1 is transmitted that is coswc1. Similarly, when the data bit is ‘0’ then the carrier signal by wc0 will be transmitted that is coswc0. The applications of frequency shift keying mainly include several modems in telemetry systems and phase shift keying.

3) PSK Digital Modulation(Phase Shift Keying)

In phase shift keying, the instant phase of the carrier signal is moved for this modulation. If the m(t) baseband signal is =1 then the carrier signal within phase will be transmitted. Similarly, If the baseband signal m(t)=0 then the carrier signal by out of phase is transmitted that is cos (wct+П). If phase shift can be done in four dissimilar quadrants then 2-bit of data will be transmitted at once. This method is an individual case of phase shift keying modulation which is known as Quadrature Phase Shift Keying or QPSK. The applications of phase shift keying include a broadband modem (ADSL), satellite communications, mobile phones, etc.

Phase Shift Keying

4) M-Ary Digital Modulation

In this modulation technique, two or more bits are made for transmitting at once on a single signal, and then it will help in reducing the bandwidth. These techniques are classified into three types namely M-ary ASK, M-ary FSK, and M-ary PSK.

Difference between Analog and Digital Modulation

The difference between Analog Modulation and Digital Modulation include the following.

Analog Modulation

Digital Modulation

An AM signal can signify any value in a range.

A DM signal can only signify with a set of discrete values.

In analog modulation (AM), the input must be in the form of analog

In digital modulation (DM), the input must be the data in the form of digital

In AM, the value between the max & min is considered to be applicable.

In DM, only two binary numbers are considered applicable such as 1 and 0.

Most of the signals that we transmit in nature are analog like voice signal, and it is much simpler to complete analog modulation compare with digital

But using digital modulation, you require transmitting through an ADC converter before transmission & a DAC at the end of the receiver for recovering the unique signal. The extra phases required to transmit DM (digital modulation) enhances both the price and difficulty of the transmitter as well as receiver.

The AM can generate a signal to carry the frequently changing data.

The DM generates a signal whose rate changes at particular time intervals.

In AM, it is not easy to disconnect the signal from noise.

In DM, the signal can simply disconnect from noise.

Thus, this is all about an overview of digital modulation methods. This modulation offers more capacity of data, digital data services with compatibility; data security is high, good communication quality, and faster system accessibility. These modulation schemes have a better capacity for conveying a huge amount of data than AM schemes (analog modulation).

Established in 2000, the Soukacatv.com main products are modulators both in analog and digital ones, amplifier and combiner. We are the very first one 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.



CONTACT US

Dingshengwei Electronics Co., Ltd

Company Address: Buliding A,the first industry park of Guanlong,Xili Town,Nanshan,Shenzhen,Guangdong,China

Tel : +86 0755 26909863

Fax : +86 0755 26984949

Phone: +86 13410066011

Email:[email protected]

Skype: soukaken

Website: https://www.soukacatv.com



Source: elprocus