Digital Modulation
Digital modulation
differents kind and aplications form them.
Digital Modulation Techniques
The techniques used to modulate digital information so that it can be transmitted via microwave, satellite or down a cable pair are different to that of analogue transmission. The data transmitted via satellite or microwave is transmitted as an analogue signal. The techniques used to transmit analogue signals are used to transmit digital signals. The problem is to convert the digital signals to a form that can be treated as an analogue signal that is then in the appropriate form to either be transmitted down a twisted cable pair or applied to the RF stage where is modulated to a frequency that can be transmitted via microwave or satellite.
The equipment that is used to convert digital signals into analogue format is a modem. The word modem is made up of the words “modulator” and “demodulator”.
A modem accepts a serial data stream and converts it into an analogue format that matches the transmission medium.
There are many different modulation techniques that can be utilised in a modem. These techniques are: • Amplitude shift key modulation (ASK) • Frequency shift key modulation (FSK) • Binary-phase shift key modulation (BPSK) • Quadrature-phase shift key modulation (QPSK) • Quadrature amplitude modulation (QAM)
List of common digital modulation techniques
The most common digital modulation techniques are: 1. Phase-shift keying (PSK): a. Binary PSK (BPSK), using M=2 symbols b. Quadrature PSK (QPSK), using M=4 symbols c. Differential PSK (DPSK) 2. Frequency-shift keying (FSK): a. Audio frequency-shift keying (AFSK) b. Multi-frequency shift keying (M-ary FSK or MFSK) 3. Amplitude-shift keying (ASK) 4. Quadrature amplitude modulation (QAM) - a combination of PSK and ASK: 5. Wavelet modulation 6. Spread-spectrum
differents kind and aplications form them.
Digital Modulation Techniques
The techniques used to modulate digital information so that it can be transmitted via microwave, satellite or down a cable pair are different to that of analogue transmission. The data transmitted via satellite or microwave is transmitted as an analogue signal. The techniques used to transmit analogue signals are used to transmit digital signals. The problem is to convert the digital signals to a form that can be treated as an analogue signal that is then in the appropriate form to either be transmitted down a twisted cable pair or applied to the RF stage where is modulated to a frequency that can be transmitted via microwave or satellite.
The equipment that is used to convert digital signals into analogue format is a modem. The word modem is made up of the words “modulator” and “demodulator”.
A modem accepts a serial data stream and converts it into an analogue format that matches the transmission medium.
There are many different modulation techniques that can be utilised in a modem. These techniques are: • Amplitude shift key modulation (ASK) • Frequency shift key modulation (FSK) • Binary-phase shift key modulation (BPSK) • Quadrature-phase shift key modulation (QPSK) • Quadrature amplitude modulation (QAM)
List of common digital modulation techniques
The most common digital modulation techniques are: 1. Phase-shift keying (PSK): a. Binary PSK (BPSK), using M=2 symbols b. Quadrature PSK (QPSK), using M=4 symbols c. Differential PSK (DPSK) 2. Frequency-shift keying (FSK): a. Audio frequency-shift keying (AFSK) b. Multi-frequency shift keying (M-ary FSK or MFSK) 3. Amplitude-shift keying (ASK) 4. Quadrature amplitude modulation (QAM) - a combination of PSK and ASK: 5. Wavelet modulation 6. Spread-spectrum