Split sound is an old system in analog

television transmitter A television transmitter is a transmitter that is used for terrestrial (over-the-air) television broadcasting. It is an electronic device that radiates radio waves that carry a video signal representing moving images, along with a synchronized ...

s. It has long been superseded, but transmitters working on this principle are still in use. In this system there are two almost independent transmitters, one for sound (aural) and one for picture (visual). The system requires more energy input relative to broadcast energy than the alternative system known as intercarrier system.

Main stages of a transmitter

All

superheterodyne transmitter Superheterodyne transmitter is a radio or TV transmitter which uses an intermediate frequency signal in addition to radio frequency signal. Types of transmitters There are two types of transmitters. In some transmitters, the information ...

s have the following stages: * Oscillators *Input stages :

Buffer amplifier A buffer amplifier (sometimes simply called a buffer) is one that provides electrical impedance transformation from one circuit to another, with the aim of preventing the signal source from being affected by whatever currents (or voltages, for a cu ...

s, correction circuits etc. * IF

modulator In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the ''carrier signal'', with a separate signal called the ''modulation signal'' that typically contains informatio ...

and IF amplifiers *

Frequency mixer In electronics, a mixer, or frequency mixer, is an electrical circuit that creates new frequencies from two signals applied to it. In its most common application, two signals are applied to a mixer, and it produces new signals at the sum and di ...

RF power amplifier A radio-frequency power amplifier (RF power amplifier) is a type of electronic amplifier that converts a low-power radio-frequency signal into a higher-power signal. Typically, RF power amplifiers drive the antenna of a transmitter. Design goal ...

s * Antenna system

Split sound TV transmitter

In split sound TV broadcasting, two of each of the above stages (except the antenna system) are required, one for sound and one for video. At the output of the RF amplifiers both signals are combined by a high-power

diplexer A diplexer is a passive device that implements frequency-domain multiplexing. Two ports (e.g., L and H) are multiplexed onto a third port (e.g., S). The signals on ports L and H occupy disjoint frequency bands. Consequently, the signals on L and ...

; the combined signal is transmitted.

Split sound vs intercarrier system

*In split sound system a high power diplexer is used at the output of the RF amplifiers. Such diplexers are expensive and bulky. In intercarrier system where the combining is achieved at a low level stage no diplexer is used. *Whereas in intercarrier system RF amplifiers are common for both the visual and aural signals, in split sound system visual and aural transmitters have separate RF amplifiers (tetrodes or klystrons). Thus, all else being equal, the power consumption of the split sound system is more than that of the intercarrier system. *In intercarrier system the two IF signals may interfere with each other to produce

interference Interference is the act of interfering, invading, or poaching. Interference may also refer to: Communications * Interference (communication), anything which alters, modifies, or disrupts a message * Adjacent-channel interference, caused by extr ...

products out of the operating channel. In order to protect the neighbouring channels a

notch filter In signal processing, a band-stop filter or band-rejection filter is a filter that passes most frequencies unaltered, but attenuates those in a specific range to very low levels. It is the opposite of a band-pass filter. A notch filter is a ...

is used. In split sound no interference products appear at the output, so no filter is needed.

References

{{Analogue TV transmitter topics Television technology Broadcast engineering