The following points require special attention when using a LQ-3031T to record video signals.
1. Standard Video signals
Please use standard video signals conforming to RS-170A. (See Fig. 41) RS-170A specifies the following values,
Color subcarrier frequency: 3.579545MHz ± 10Hz
Synchronizing signal amplitude: 0.286Vp-p Amplitude of video signal: 0.714Vp-p
100 90 80 70 60 50 40 30 20 10 0 10 20 30 40 -IRE SCALE UNITS
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M Dnito r shov ving [1 s
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d sigr lal waveforrr
1 Vp-p
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Attempting to record signals that differ substantially from standard signals may result in the problems indicated below.
2. Color subcarrier frequency
The color subcarrier frequency used should comply with the 3.579545MHz±10Hz specification described above.
Since standard signal generators are generally expensive, there may be cases where use of non-standard signals is unavoid-able. In these cases, the error should be kept to within ±50Hz.
Color may be lost if the frequency differs substantially.
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-3. Adjusting the recording level
The LQ-3031T recording level can be adjusted both automatically or manually.
When recording with automatic level adjustment, the recording level is adjusted by an AGC circuit as specified below.
1) Input amplitude less than 1.1Vp-p
Gain is controlled to give a synchronizing signal amplitude of 0.286Vp-p.
2) Input amplitude greater than 1.1Vp-p
Gain is controlled to give an amplitude no greater than 1.1Vp-p for the whole video signal.
The amplitude of the input signal should therefore be set to no more than 1.1Vp-p. If signals with larger amplitudes are input, the size of the synchronizing signal component of the recorded signal may be reduced. If this happens, the following problems may result:
1) Wavering images 2) Distorted images 3) Vertical Jitter 4) Inability to Gen Lock
When recording manually, the amplitude of the input signal synchronizing signal is detected, and a green LED lights up when the level reaches the standard value. Excessive inputs do not compress the synchronizing signal when the recording level is controlled manually.
However, when recordings are made manually, there may be points where there are extremely high level input video signals.
The following problems may occur at these points.
1) Black or white "grass" distortion, similar to dropouts.
2) White-out, or loss of detail.
The output signal from the camera should therefore be monitored by a waveform monitor or oscilloscope, to set the signal to a standard level.
4. Input signals from the camera
The level of input signals from the camera varies greatly by adjustment of the camera and differences in lighting conditions.
In particular, if a light shines directly into the camera, part of the camera input is a very strong light. If this happens, the exact result depends on the characteristics of the camera, but parts of the signal may have excessive amplitudes, even if the camera adjustment is set with an auto-iris. This may result in the problems described in the preceding section.
(See Fig. 42)
To prevent this sort of problem, the video signals from the camera should be monitored by a waveform monitor or oscillos-cope, so that if the output becomes too large, it can be adjusted manually or the illumination angle or distance and be altered.
Particular care should be taken to control the input signal level if the recording is to be used as a master for taking copies.
IRE
100
-40
[Fig. 42]
Signal with areas of excessive amplitude.
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-5. Special consideration when shooting small objects
The following special considerations apply when a camera is taking pictures of small object with a close-up lens or similar device.
(1) The type of close-up lense, lighting considerations and aperture greatly affect the depth of field. If the depth of field is small, the parts that are not in focus appear blurred on the screen. This may produce color smear. One way of avoiding this is increasing the lighting intensity to increase the depth of field. Another method is to raise the camera sensitivity and reduce the aperture.
(2) When the object and the illumination are brought close together, there is a greater chance of the illumination entering the camera directly or reflecting strongly into the camera lens. The camera output should be monitored carefully to adjust the illumination untill a good output signal is obtained.
(3) If the background is while and is very close to the object, the color of the object may be reflected, coloring the background.
This can be avoided by moving the object and background further apart or by changing the background color so that the reflected color is not obtrusive.
(4) Keep color saturation low. It provides a much better looking duplicate. Avoid recording images which have large amounts of chroma which fall below 0 I.R.E. units.
6. Disc duplication considerations
When making a master disc for making copies be careful so time base errors and sync dropouts are not recorded into the master; otherwise the duplicate will have the same errors, and they will tend to be magnified in the duplication process.
For this reason it is strongly recommended that a Time Base Corrector (TBC) be used to ASSURE quality recordings time after time.1*11
1,11 Be sure to connect advanced vertical sync from the TBC when employing automatic frame duplication. This will assure frame accurate duplication.
Also any playback source such as VCR or off air TV signal should be passed through a TBC or frame synchronizer to assure quality recordings.
• R E C O R D I N G F R O M A V C R [LQ-3031Tonly]
A. Direct recording from a VCR is possible, but
(1) The recording will be interrupted if a loss of video input is encountered.
(2) Time base errors will cause the image to waver or jitter upon playback (edit points are a good example). The disc will not Gen Lock.
(3) Poor framing or poor sync on the source tape can cause random frames to be misrecorded or not recorded at all.
(4) Time base error from the tape will be impregnated into the disc; hence Gen Lock will be poor and copies will look terrible.
The examples cited here, and others, can cause only one field of the frame to be recorded; therefore the frame will be damaged and unusable
the recorded check will detect the frame as blank but you will not be able to record there the picture will blink on and off or be very unstable
and the Gen Lock function will be adversely affected.
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