Modulator VIDEO

Objectives:

1. Measuring the frequency spectrum of video transmission.
2. Determine the carrier frequency range image and sound carrier frequency.
3. Specifies the field width (bandwidth) on video transmission.
4. Specify the type of modulation on the picture and sound.


Equipment Used:

1 Modulator video (VCD / VTR / video sender).
A Spectrum Analyzer.
An RCA cable connector - BNC.


Circuit diagram:

Basic Theory:
How to emit (transmit) signal is amplitude modulated image similar to a radio broadcasting system that has been known. In both cases, the amplitude of a carrier wave radio frequency (RF) is made varies with the modulating voltage. Modulation is a signal of fundamental frequency (baseband). On television, this baseband signal is a composite video signal. Broadcast television is really such a radio system, but includes pictures and sound. Sound signal emitted by joining in it frequency modulation (FM) on a separate carrier wave transmitter in the same channel as the image signal.
Understanding the image signal is used here to mean a modulated carrier wave. The video signal is a signal to a picture tube. Video signal to television audio signal corresponds to the sound system. Details are clearer than the image signal AM (amplitude modulation picture) and an FM voice signal.

 

Figure 2.a shows the frequency spectrum of video transmission that produces an image signal comprising AM picture carrier frequency (center frequency) and sound carrier frequencies (frequency side of the upper and lower side frequencies) - without VSB, while Figure 2b shows the frequency spectrum in transmission generate video image signals of AM frequencies only have the upper side only (with VSB).

Experimental Procedure:

1. Calibration Spectrum Analyzer to determine the reference spectrum.
2. Set-up instruments like in the picture above.
3. ON the instrument.
4. Measure the output video modulator (RF) using the Spectrum Analyzer and observe the frequency spectrum.
5. Image of the frequency spectrum.
6. Determine how much an image carrier frequency, carrier frequency sounds, and the difference frequency picture carrier and sound carrier frequency.
7. Observe the spectrum, determine the type of modulation used in transmission, by way of changing the freq. SPAN (reduced scale).
8. Figure spktrum frequencies multiples of the base frequency.


Question:

1. What system is used in the video modulator?
2. From step 6, how to know what types of modulation?

Experimental results:

 

Gambar Spektrum Frekuensi	Keterangan
	Ref = 102dBµ BW = 100 KHz CF = 5 MHz CP1ΔF + 4,32 MHz 2 MHz / DIV ΔV + 18,8 dB Frekuensi Pembawa Gambar : LSB = 5 MHz - 4,32 MHz USB= 5 MHz + 4,32 MHz Frekuensi pembawa suara : tidak dapat dilihat dengan spectrum analyzer karena frekuensi sangat kecil
	Ref = 102dBµ BW = 100 KHz CF = 214 MHz CP1ΔF + 4,32 MHz 2 MHz / DIV ΔV + 18,8 dB Frekuensi Pembawa Gambar LSB = 214 MHz -  4,32 MHz USB= 214 MHz + 4,32 MHz Frekuensi pembawa suara : tidak dapat dilihat dengan spectrum analyzer karena frekuensi sangat kecil
	Ref = 102dBµ BW = 100 KHz CF = 421 MHz CP1ΔF + 4,32 MHz 2 MHz / DIV ΔV + 18,8 dB Frekuensi Pembawa gambar : LSB = 421 MHz - 4,32 MHz USB= 421 MHz + 4,32 MHz Frekuensi pembawa suara : tidak dapat dilihat dengan spectrum analyzer karena frekuensi sangat kecil
	Ref = 102dBµ BW = 100 KHz CF = 624 MHz CP1ΔF + 4,32 MHz 2 MHz / DIV ΔV + 18,8 dB Frekuensi Pembawa Gambar : LSB = 624 MHz - 4,32 MHz USB= 624 MHz + 4,32 MHz Frekuensi pembawa suara : tidak dapat dilihat dengan spectrum analyzer karena frekuensi sangat kecil
	Ref = 102dBµ BW = 100 KHz CF = 831 MHz CP1ΔF + 4,32 MHz 2 MHz / DIV ΔV + 18,8 dB Frekuensi Pembawa Gambar : LSB = 831 MHz - 4,32 MHz USB= 831 MHz + 4,32 MHz Frekuensi pembawa suara : tidak dapat dilihat dengan spectrum analyzer karena frekuensi sangat kecil
	Ref = 102dBµ BW = 100 KHz CF = 1055 MHz CP1ΔF + 4,32 MHz 2 MHz / DIV ΔV + 18,8 dB Frekuensi Pembawa Gambar : LSB = 1055 MHz - 4,32 MHz USB= 1055 MHz + 4,32 MHz Frekuensi pembawa suara : tidak dapat dilihat dengan spectrum analyzer karena frekuensi sangat kecil

Picture Frequency Spectrum

LSB = 5 MHz - 4,32 MHz

USB= 5 MHz + 4,32 MHz

Picture Carrier Frequency:

Voice carrier frequency: can not be seen because of the frequency spectrum analyzer with very small

DATA ANALYSIS:

1. Viewed from the image spectrum that we get can we know that the value of
Carrier frequency: 421 MHz
CP1ΔF + 4.32 MHz
Then:
USB = 421 MHz + 4.32 MHz = 425.32 MHz
LSB = 421 MHz - 4.32 MHz = 416.68 MHz
Voice carrier frequency: can not be seen because of the frequency spectrum analyzer with extremely small compared with the frequency carriernya.
2. For frequencies multiples:
• Frequency of multiples of 1 in: 5 MHz
• Frequency of multiples of 2 on: 214 MHz
• Frequency of multiples of 3 on: 624 MHz
• Frequency of multiples of 4 at: 813 MHz
• Frequency of multiples of 5 in: 1055 MHz

ANSWER QUESTIONS:
1. Modulation system used in the video are AMPLITUDE MODULATION, because the signal amplitude information affect the amplitude of the carrier signal, the signal information into the cover of the carrier signal.

A common use of signal Am is: AM radio broadcasting is widely used for broadcast AM radio wave signal, the TV picture (Video), Radio communication: aircraft, amateur radio (SSB), CB radio (Citizens Band Radio 􀂶). Digital data transmission: Modems Computers (combination with QAM modulation)

2. Known types of modulation are amplitude modulation can be seen from the changes in amplitude and has a spectrum of AM.
Based on the equation of the spectrum signal modulated AM AM will have 3 (three frequencies):
• fc: carrier frequency signal
• LSB: Lower Side Band frequency (LSB), namely the difference frequency carrier signal and the signal information.
• USB: Upper Side Band frequency (USB) is the number of carrier signal frequency and signal information.

CONCLUSION
1. In a video modulator that is used is amplitude modulation Modulation (AM)
2. AM modulation is shown on a spectrum analyzer displays the three frequencies namely
- carrier frequency (fc)
- Frequency of Lower Side Band (LSB)
- Frequency of Upper Side Band (USB)
3. The difference between USB and LSB frequencies are = 4.32 MHz
4. Used 100 KHz bandwidth

EXPERIMENT 1 PATTERN GENERATOR

Objectives:

1.1 Getting to know the basic patterns in the Pattern Generator.
Measuring 1.2 standard composite video and voltage on each pattern.
Measuring 1.3 on the modulator wave modulated video (RF).
Measuring 1.4 video IF.


Equipment Used:

1 Pattern Generator TV signal, LODESTAR CPG-1367A
1 Oscilloscope 40 MHz and passive probe
1 Power Supply
A cable connecting the BNC W- BNC 75
A BNC connector cable - RCA 75 W
1 T-BNC Connector

Circuit diagram:

Theory Platform:

Source of image patterns (pattern generator) is the technique of video (television) for the purpose of setting up or finding fault. There are various kinds of image patterns with a variety of needs. Pattern of so many images that exist, there are several commonly used image patterns are not very specific uses. 

Types of Image and its Use Patterns

A. Spots (Dot)

To check and adjust the static convergence in the middle of the screen with a low brightness. This should be done according to the television manufacturer's instructions.

B. The boxes (crosshach)

Plaid pattern with horizontal lines and vertical lines with the background color of black and white color line.
1. To check and adjust the horizontal and vertical dynamic convergence and the convergence angle.

2. By linearity of deflection (deflection) the correct horizontal and vertical, horizontal white lines should be a rectangular equilateral.

If not, then the plane can be checked for truth response amplitudes. Vertical white line width should be 200 ns.

If this line is not sharp and visible lower intensity than the horizontal line, the amplitude response is possible recipient is not enough.

If vertical lines appear double, receiver circuit may be vibrating.

3. To pin-cushion proofreaders check the receiver. With the convergence of the right, square in the corner of the screen should be approximately equal to a square in the middle of the screen at a distance of normal vision.

C. White (white)

This pattern contains a signal 100% white (without color information) with alternating burst.

1. Images for constant brightness on the entire screen (tida no hum, etc..)

2. Color picture tube for setting a good white (white-D).

3. Limitation of fire flow on the color picture tube.

4. For the video recorder is ideal pattern for the current setting of writing (recording) luminance. This pattern can also to set the FM demodulator (setting white level).

D. Beam Color (color) 

Blocks of colors (color bar) consists of 8 vertical color bar standard and a reference beam horizontally. Beams 8 colors are arranged in order of depreciation luminan. From left to right beams D color is white, yellow, cyan, green, magenta, red, blue, and black.
This pattern is used to set the operational control of the receiver at the correct position.
Horizontal beam (white level) on the bottom of this pattern is used as a standard when setting the amplitude signal of color differences with relationships with luminan signal in the picture tube. Signals can be used for resetting the signal amplitude of the demodulator circuit and the matrix, as the output can be compared with the reference beam. In addition to the above purposes, this pattern can be used to check the overall color appearance. So can also be used checks and settings on the receiver or VCR:
1. Lock Inspection burst.
2. AGC examination of color and which create the color.
3. Examination series reactance of the subcarrier regenerator.
4. Examination of the regenerator subcarrier synchronization.
5. Checking circuit identifier (identification) PAL.

Signal Synchronization
Synchronization signal is a signal that is always given periodically and remains, serves to drive a raster scanning path in every television set so that the formation of the video signal into an image and the exact arrangement will remain the same as the original position in the field of raste
camera (picture production), therefore the synchronization signal is always supplied along with the video signal sent anywhere. For the formation of this raster scanning system will require two kinds of synchronization are:

- Namely the horizontal synchronization signal to the horizontal scanning provided at each horizontal retrace.
- Vertical sync signal is for vertical scanning provided on each vertical retrace. 

Video signal which is equipped with synchronization signals called the complete video signal (Composite Video signa / CVSl), while for color video signal is called Color Composite Video Signal (CCVS). Because the video signal has been added color information signals, ie signals and signal Burst Color Sub Carrier.

Experimental Procedure: 

1. Set-up equipment such as in the picture above.
2. Connect the pattern generator with the power supply 8, 5 V, then ON the instrument.
3. Pattern generator output switches on and observe put on VIDEO waveforms for each pattern.
4. Observe and picture synchronizing signal and horizontal blanking, vertical blanking, front and rear porch,     and image information of each pattern.
5. Images and specify voltage waveforms.
6. Pattern generator output switches on and observe put in the IF waveform for each pattern and the measuring frequency.
7. Image of the wave form and specify voltage.
8. Image signal for one frame (still image) in composite video, determine the level and periodanya.

Experimental results:

 On VIDEO OUTPUT SWITCHES

Gambar pada Televisi	Pattern Generator pada VIDEO	Ket	Tegangan
DOTS :		V/D =0,5V T/D = 1ms	1,9volt/div
CROSS HATCH :		V/D = 0,5V T/D = 1 ms	1,8 volt/div
VERTICAL LINES :		V/D = 0,5V T/D = 0,2ms	1,8 volt/div
HORIZONTAL LINES :		V/D=0,5V T/D=0,2ms	0,8volt/div
RASTER :		V/ D =0,5V T/D = 0,2 ms	1,9volt/div
COLOR :		V/D = 0,5V T/D = 0,2 ms	1,35volt/div

On IF OUTPUT SWITCHES Pola Gambar Pattern Generator pada IF Ket Tegangan Frekuensi DOTS V/D = 0,1 V T/D = 1 ms 0,36 volt/div 11KHz CROSS HATS V/D = 0,1 V T/D = 0,2 ms 0,34 volt/div               52KHz HORIZONTAL LINES V/D = 0,1 V T/D = 0,5 ms 0,34 volt/div 22KHz VERTICAL LINES V/D =0,1V T/D =0,2ms 0,34 volt/div 50KHz RASTER V/D = 0,1 V T/D = 0,2 V 0,34 volt/div 55KHz COLOR V/D = 0,1 V T/D = 0,1 ms 0,38volt/div 111KHz DATA ANALYSIS: CALCULATING VOLTAGE:    1. On VIDEO OUTPUT SWITCHES     Voltage (V) = Amplitude x Volts / DIV A. DOTS: V = A x V / div = 3.8 x 0.5 V = 1.9 volts / div B. CROSS Hatch: V = A x V / div = 3.6 x 0.5 V = 1.8 volts / div C. VERTICAL LINES: V = A x V / div = 3.6 x 0.5 V = 1.8 volts / div             D. HORIZONTAL LINES: V = A x V / div = 1.6 x 0.5 V = 0.8 volts / div E. Raster: V = A x V / div = 3.8 x 0.5 V = 1.9 volts / div F. COLOUR: V = A x V / div = 2.7 x 0.5 V = 1.35 volts / div      2. On IF OUTPUT SWITCHES Voltage (V) = Amplitude x Volts / DIV A. DOTS: V = A x V / div = 3.6 x 0.1 V = 0.36 volts / div B. CROSS Hatch: V = A x V / div = 3.4 x 0.1 V = 0.34 volts / div C. VERTICAL LINES: V = A x V / div = 3.4 x 0.1 V = 0.34 volts / div D. HORIZONTAL LINES: V = A x V / div = 3.4 x 0.1 V = 0.34 volts / div E. Raster: V = A x V / div = 3.4 x 0.1 V = 0.34 volts / div F. COLOUR: V = A x V / div = 3.8 x 0.1 V = 0.38 volts / div       IF OUTPUT FREQUENCY COUNTING on The formula Period = Time / div: waves in 1 period Frequency = 1: Period Description: Period (T)            Frequency (f)       Waves in 1 period (G) In view osciloskop assumed 1 box = 1 wave 1. DOTS T = Time / div: G = 1 ms: 11 wave                   = 90 μs f = 1 / T = 1 / 90 μs = 11 KHz 2. CROSS Hatch T = Time / div: G = 0.2 ms: 10.5 wave                   = 19 μs f = 1 / T = 1 / 19 μs = 52 KHz 3. VERTICAL LINES T = Time / div: G = 0.2 ms: 10 wave                   = 20 μs f = 1 / T = 1 / 20 μs = 50 KHz 4. HORIZONTAL LINES T = Time / div: G = 0.5 ms: 11 wave                   = 45 μs f = 1 / T = 1 / 45 μs = 22 KHz 5. Raster T = Time / div: G = 0.2 ms: 11 wave                   = 18 μs f = 1 / T = 1 / 18 μs = 55 KHz 6. COLOUR T = Time / div: G = 0.1 ms: 11 wave                   = 9μs f = 1 / T = 1 / 9μs = 111 KHz CONCLUSION 1. Voltage at all about the same video system. 2. At the time of the IF mode is turned down because the amplitude of the voltage will also be down 3. IF output frequency is also almost the same because there is no significant difference in amplitude. 4. Tension on the composite video is lower than the voltage on any other video system