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Colour television
Published in John Watkinson, Television Fundamentals, 1996
So far only baseband television signals have been discussed. In order to broadcast such signals, they need to modulate a suitable carrier. In terrestrial television systems, amplitude modulation (AM) is used. Figure 2.34 shows that in AM, the voltage of the video signal is used to control a multiplier which determines the amplitude of the carrier. In practice there are some complications. Firstly, conventional AM produces symmetrical sidebands above and below the carrier frequency, effectively doubling the spectrum width required. Conventional AM is also known as double sideband (DSB). In communications, a technique known as single sideband (SSB) exists, in which only one sideband is transmitted. This occupies half the spectrum space, but requires a complex receiver which has to regenerate the carrier frequency. This approach was considered too expensive for TV receivers and so a compromise was reached in which the carrier and the upper sideband is transmitted intact, but most of the lower sideband is suppressed to leave what is called a vestigial sideband. In vestigial sideband working (VSB or AM-VSB) the receiver is no more complex than in the double sideband system, but a useful spectrum saving is obtained.
Audio routing and transmission
Published in John Watkinson, Audio for Television, 1997
Conventional AM is also known as double sideband (DSB). In communications, a technique known as single sideband (SSB) exists, in which only one sideband is transmitted. This occupies half the spectrum space, but requires a complex receiver which has to regenerate the carrier frequency. This approach was considered too expensive for television receivers and so a compromise was reached in which the carrier and the upper sideband is transmitted intact, but most of the lower sideband is suppressed to leave what is called a vestigial sideband. In vestigial sideband working (VSB or AM-VSB) the receiver is no more complex than in the DSB system, but a useful spectrum saving is obtained.
Analog Modulation for Mobile Radio
Published in Michel Daoud Yacoub, Foundations of Mobile Radio Engineering, 2019
The standard AM scheme has in its favor ease of implementation and spectrum saving: Demodulation can be carried out by means of an envelope detector or a square-law detector, and the transmission bandwidth is only twice the message bandwidth. On the other hand, additional power is required to transmit the carrier. SSB modulation requires the minimum transmitter power and minimum transmission bandwidth but the receivers are more complex. The FM scheme usually needs more frequency spectrum but yields better performance in the presence of noise.
Practical method for nullifying ripple effect from FIR-Hilbert transformer
Published in International Journal of Electronics Letters, 2023
Single Sideband (SSB) is attractive for narrow-band radio systems owing to its two advantages of lower transmitting power and less bandwidth. However, it is difficult to implement SSB transceivers that can work well in severe fading environments. Then, asynchronous demodulation methods for Real Zero SSB (RZ SSB), which is equivalent to SSB with a reduced carrier whose level is 13.2 dB below the Peak Envelope Power (PEP; ARIB STD-T62 Version 2.0, 2008), were developed using Hilbert transform. Unprecedented reception performances on RZ SSB are achieved; that is, there is no threshold effect and ensures great immunity for severe fading encountered in land mobile radio paths (Daikoku, 2021a).