Try signal conditioning the audio video for an RF modulator

Posted on Feb 5, 2014

Despite the need for an IC, this ubiquitous interface between the modulator and audio-video signals has not been reduced to an integrated circuit. The major reasons for that deficiency are the difficulty of such a design, the variations required for different standards, and the variable levels required by the modulator itself. The alternative to a

Try signal conditioning the audio video for an RF modulator

Click here to download the full size of the above Circuit.

n IC interface is a discrete design. The signal-conditioning requirements include lowpass and notch filtering of the video, group-delay compensation for the video, pre-emphasis for the audio, and (to adjust the modulation level) level controls for both audio and video. Because many cable and satellite receivers, VCRs, DVDs, and TVs don`t fully comply with these signal-conditioning requirements, the modulated signals of channels 3-4 have poorer quality than that of the baseband composite (Cvbs). The discussion below explains the interface requirements and how to meet them using standard op amps and discrete components. The resulting low-cost circuitry can also provide rear-panel outputs for most audio/video (A/V) appliances. For driving RF modulators in NTSC and PAL systems, the allowable video group-delay variation and required audio pre-emphasis are clearly specified by ITU Recommendation BT. 470-6. Most of the other specifications, not as obvious, are summarized and extrapolated to include other, unstated design specifications (Tables 1-2). Those table entries are based on typical back-panel outputs for a TV, DVD, or set-top box having both baseband and RF-modulated A/V outputs (Figure 1). Some of these requirements depend on the source. If the signals to the modulator come from a DAC, for example, they obviously need reconstruction filtering to prevent out-of-band modulation and to remove artifacts, noise, and aliased...

Visit page

Leave Comment

characters left:

Related Circuits

Linear Resistance Meter

Most analogue multimeters are capable of measuring resistance over quite a wide range of values, but are rather inconvenient in use due to the reverse reading scale which is also non-linear

Linear Video Amplifier SECAM PAL and NTSC

Buffered video amplifier is used wherever the use of video player to the receiver / monitor TV with a long cable may cause a drop in signal amplitude and as a consequence, the deterioration in...

Liquid detector water sensor circuit

This is a very simple liquid detector that use a relay to open an evacuation van. You can use it for water or any liquid that conduct electricity. Use any.

Lithium Ion charger circuit using LM3632

Lithium Ion charger circuit design electronic project using LM3632 controller.

Logic Probe for Tri-state Logics

This is a simple circuit of Logic Probe for Tri-state Logics. This circuit can be built only in a few hours. Besides that, this circuit has some other.

Long-Range IR Transmitter

Most of the IR remotes work reliably within a range of 5 metres. The circuit complexity increases if you design the IR transmitter for reliable operation over a longer range, say, 10 metres. To...

Low-cost-frequency-counter

This counter uses a four-digit display, but with a flip of the range switch, it can display frequencies from 1 to 40 MHz, with a resolution of 100Hz. The MM74C926 CMOS IC contains a four-digit...

Low-frequency-tachometer

This tachometer lets you measure heartbeats, respiratory rates, and other low-frequency events that recur at intervals of 0.33 to 40.96 seconds. The circuit senses the period offm, computes the...

New Circuits

Zero consumption Anti-theft High power Code Switch for E-Bike Batteries

This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
Ultrasonic distance finder circuit

The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Simple Metal detector circuit with CD4030

Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Fully automatic watering circuit for flower pots

Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
Simple deep searching metal detector circuit

The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
Sub-Harmonic Bass Converter for Electric Guitars

The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
Echo Depth Sounding Sonar for Boats

In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
100W HiFi Audio Amplifier Circuit

This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
Plant-Pot Water Level Indicator Circuit

A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....

Create NOW your QR MENU for your Restaurant / Hotel / Bar / Caffe,

Comprehensive ordering/paying features. fully personalized to suit your Business.

Update Anytime! Easy and Simple!

Popular Circuits

Gas-temperature-monitor-detection

This circuit can be used to measure exhaust gas temperature in a furnace. The 10-bit LTC1091A...

Low-distortion-video-buffer

This buffer amplifier"s overall harmonic dis tortion is a low 0.01 % or less at 3-V rms output...

Oscillator Design Guide Structure

The Oscillator DesignGuide is integrated into Agilent EEsof`s Advanced Design System environment,...

Regulated Positive Voltage Booster

When Q1 is active, a larger current begins to flow through L1 to GND. When Q1 is switched off,...

high efficiency white led driver

This white LED Driver circuit project is based on the NCP5680 high efficiency white LED Driver...

5 Dot Led Level Meter

The Allegro ® A8732 is a Xenon photoflash charger IC designed to meet the needs of ultra low...

Electronics as a Hobby

A single chip circuit for Echo & Delay. If you can modify a mic mixer circuit, you can easyly use...