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Sep 14, 2017

ASK and FSK difference

I. Introduction

(1), FSK profile

FSK (Frequency-shift keying): frequency shift keying. Is to use the digital signal to modulate the carrier frequency. Is the use of information transmission in an earlier modulation, its main advantages are: to achieve easier, anti-noise and anti-attenuation performance is better. In the low-speed data transmission has been widely used. It is the use of baseband digital signal discrete value characteristics to key carrier frequency to transmit information of a digital modulation technology.

(2), ASK Introduction AsK: 

Amplitude Shift Keying ASK (Amplitude Shift Keying) ASK refers to the amplitude keying mode. This modulation is based on the signal, adjust the amplitude of the sine wave. Amplitude keying can be achieved by means of multipliers and switching circuits. The carrier is turned on or off under the control of the digital signal 1 or 0, and the carrier is on in the state of signal 1. At the same time, the carrier is on the transmission channel; when the signal is 0, the carrier is turned off, and the transmission channel No carrier transmission. Then at the receiving end we can according to the presence or absence of the carrier to restore the digital signal 1 and 0. The bandwidth of the binary amplitude keying signal is twice the width of the binary baseband signal. Amplitude shift keying (ASK) carrier amplitude is with the modulation signal changes, the simplest form is that the carrier in the binary modulation signal control off, this time can be called the key switch method (OOK) The Multi-level MASK modulation is a more efficient transmission, but because of its poor ability to resist noise, especially anti-fading ability is not strong, it is generally only suitable for use in the constant channel.

2. Difference

(1), FSK is FM, ASK is amplitude modulation. The details are as follows:

Amplitude keying (ASK): that is, according to the amplitude of the carrier by the digital data modulation and take different values, such as the corresponding binary 0, the carrier amplitude is 0; corresponding to binary 1, carrier amplitude is 1. AM technology is simple to implement, but is susceptible to changes in gain. On a telephone line, it usually only achieves a rate of 1200 bps.

Frequency Shift Keying (FSK): The frequency of the carrier is modulated by the value of the digital data (0 or 1). For example, the carrier frequency corresponding to binary 0 is F1, and the carrier frequency corresponding to binary 1 is F2. The technology has good anti-jamming performance, but occupies a larger bandwidth. In the telephone line, the use of FSK can achieve full-duplex operation, usually up to 1200bps rate

2, distance: FSK launch distance longer than the ASK .

3.The same

FSK, ASk can be used as  transmitter / receiver module.

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