Lower single sideband
Most voice signals occupy about 3 kHz of bandwidth.
The former audio limitation was 15 kHz resulting in a channel occupied bandwidth of 30 kHz.
The best way of thinking of SSB modulation is to first consider an amplitude modulated signal.
Then is a useful mathematical concept, called an analytic signal.Examples: radio and optical communications.In other words, it is just another stage of heterodyning.(mixing down to base band).By removing some of the components of the ordinary AM signal it is possible to significantly improve its efficiency.Carrier and one sideband are completely suppressed.Weaver modulator edit Another variation, the Weaver modulator, 8 uses only lowpass filters and quadrature mixers, and is a favored method in digital implementations.So, the amplitude modulation has low efficiency.In the first instance, the carrier is removed it can be re-introduced in the receiver, and secondly one sideband is removed both sidebands are mirror images of one another and the carry the same information.DSL modems implement suppressed carrier SSB modulation as well.
Example: analog video recorder (vhsvrc) Separate the signals in the frequency domain.
2.4 DSB Demodulation The demodulation process of a dsbsc signal involves obtaining wo kann ich farbige frauen kennenlernen the original information signal or scaled version of it from the modulated signal.Displaystyle mathcal F-1S_mathrm a (f-f_0)s_a(t)cdot ej2pi f_0ts_textssb(t)jcdot widehat s_textssb(t)., Therefore, with Euler's formula to expand e j 2 f 0 t, displaystyle ej2pi f_0t, we obtain.1 : s s s b ( t ) R e s a ( t ).1.2 Amplitude modulation Amplitude modulation 1 is a type of modulation where the amplitude of the carrier signal is varied in accordance with the information bearing signal.The method was popular in the days of vacuum tube radios, but later gained a bad reputation due to poorly adjusted commercial implementations.A signal at frequency f 0 amplitude-modulated onto a carrier wave at f m can be expressed as simple multiplication of two cosine waves: cos(0)cos( m where x 2.The baseband frequency it needs to be shifted to is F b displaystyle F_b, 2000 Hz.A(t) is also known as the envelope of the modulated signal.When the signal is multiplied by (aka ' heterodyned with the BFO waveform, it shifts the signal to and to, which is known as the beat frequency or image frequency.Linear modulation is very necessary to obtain a not interfered signal at the receiver.When a steady state carrier is modulated with an audio signal, for example a tone of 1 kHz, then two smaller signals are seen at frequencies 1 kHz above and below the main carrier.