Interview Questions.

Question 1. What's The Difference Between Hardware Compression And Software Compression?

Answer :

Hardware Compression: Both Capturing Video Signal and Compressing Video Signal are finished with the aid of DSP chipset integrated on DVR Board. It would not need the pc's CPU to do that paintings. It's low price of CPU and RAM resources. In this system the laptop CPU's task recognition on answering network request, streaming the video/audio to network and saving recorded records to neighborhood difficult disk.

Software Compression: The DVR Board best capture video signal however does not compress it, it is the pc CPU and RAM to do this compression paintings. It's high cost of CPU and RAM resources. In this gadget the computer CPU and RAM are regularly overloaded. It is less difficult to crash than hardware compression device.

Question 2. How Do I Choose The Correct Camera For My Application?

Answer :

This in trendy is a comparatively hard choice. Many aspects of the set up ought to be taken into consideration if you want to achieve the ideal performance that meets your requirements.
A excessive-resolution camera have to be taken into consideration where more detail of scene is required. E.G. Color 460 TVL, Monochrome 570 TVL. Choosing a extra sensitive digicam will enhance duplicate in poorly lit areas. The sensitivity of a camera is indicated by way of the minimal amount of mild in order for the digital camera to provide a usable picture. E.G. Color 1.Zero Lux at F1.2.
A conventional camera produces a faded backdrop while an object is shot towards a shiny background. BLC (Back Light Compensation) will counter robust mild resources keeping photo quality.
Concentrated mild assets directed toward the digicam (e.G. Vehicle head lamps) may be inverted by means of an elective height white inverter or an eclipse feature. This has the effect of bringing element to areas and making an item clean, that might otherwise be shadowed.
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Question 3. How Do I Set Up A Camera And Lens For Use In Low Light Conditions And Or With Infra Red Lighting?

Answer :

When putting the again consciousness of a Color camera for low light conditions you have to place an ND1 (Neutral Density) filter out in the front of the lens. When setting the lower back recognition of a Mono digital camera for low mild conditions you ought to place an ND3 (Neutral Density) filter out in front of the lens. When setting the lower back recognition of a Mono digital camera equipped with I/R lights for low mild conditions you need to region an IRP (Infra- Red Pass) filter out in the front of the lens.

Question 4. What Are Osd Cameras?

Answer :

OSD (On Screen Display) cameras have a menu gadget in the digicam assembly that may be accessed so that you can set functions which include Iris tiers, AGC on/off and most capabilities of trendy and superior cameras.

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Question 5. Why Do I Have A Clear Sharp Picture During The Day And It Is Out Of Focus At Night?

Answer :

This is due to the depth of field changing because the light situations trade and may be effortlessly triumph over by using following set processes.

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Question 6. When Can I Use A Manual Iris Lens?

Answer :

A fashionable rule of thumb is handiest to use a MI lens in an internal software. This is due to the fact you're reliant at the electronic circuitry of the digital camera compensating for light changes in the scene and this is not able to compensate to the identical diploma as that of an Auto Iris lens.

Question 7. How Do I Back Focus A Camera Fitted With A Fixed Focal Length Lens?

Answer :

This is completed with the aid of following five simple steps:

Set the physical focus of the lens to infinity (clockwise from the front).
Aim the digital camera at the issue to be considered.
Release the digicam back recognition mechanism.
Adjust the lower back consciousness to reap the fine feasible photo.
Secure the cameras back awareness mechanism.
Question eight. How Do I Connect An Auto Iris Lens To A Camera?

Answer :

This is usually performed by way of a easy plug-in connection to the rear or aspect of the digicam. However you ought to always talk over with the relevant camera manual.

Question nine. What Is The Difference Between Auto Iris And Direct Drive Lenses?

Answer :

An Auto Iris lens is one which automatically adjusts its iris for adjustments inside the scene lights tiers. The motor that opens and closes the iris is driven via an Amplifier that approaches a small digital sign changing with the light degree.
A Direct Drive 'DD' lens does no longer have this Amplifier and might only operate with a camera equipped with one.
A camera specification will indicate the available output alternatives.
Question 10. Does The 'f' Stop Matter When Choosing A Lens?

Answer :

Yes, lenses are commonly precise as having a minimal and most 'f' forestall rating; the 'f' forestall is a measure of how correctly the lens permits light from the scene, to skip via the lens and onto the camera CCD sensor. The most aperture (while the lens is absolutely open), is the minimum 'f' prevent wide variety and the minimal aperture, (just before the lens absolutely closes) is the most 'f' forestall range.

A low minimum 'f' prevent number means that the lens can bypass extra mild through in the course of darkish conditions, with the intention to produce better images at night time.

A excessive maximum 'f' forestall number can be vital where there may be a high degree of mild or reflection. This will prevent the camera ‘whiting out’.

Question eleven. How Do I Back Focus A Camera Fitted With A Zoom Lens?

Answer :

This can be performed by way of following these steps:

Set the lens to complete extensive angle view.
Set the physical attention of the lens to infinity (clockwise considered from the the front).
Aim the digital camera at an item at least 30 Meters away.
Release the camera lower back awareness mechanism.
Adjust the again cognizance to achieve premier readability.
Zoom the lens in to complete telephoto and attention on a close-by object.
Keep this object in view as you slowly zoom out and if all is ready efficaciously it should stay in awareness (track).
Secure the back consciousness mechanism.
Question 12. How Do I Set Up An Auto Iris Lens?

Answer :

An Auto Iris lens has  'pots' on the side typically marked ALC (Automatic degree manipulate) and LEVEL.

The ALC manipulate has settings of PEAK and AVERAGE (P+A).

The LEVEL control has HIGH and LOW settings 'H+L'.

ALC:

The adjustment permits control over any shiny regions within the scene e.G. Sun mirrored image via home windows, street lighting and many others. There are two settings PEAK and AVERAGE.
If set to PEAK, shiny regions inside the scene are taken into consideration more, decreasing the assessment within the surrounding vicinity. This allows more element to be seen within the bright areas.
If set to AVERAGE the lens takes the bright areas less into account which generally causes over brightness or flare in these areas, but raising the evaluation of the encompassing area.
LEVEL:

The handiest accurate way to set the VIDEO LEVEL is by using the use of an oscilloscope, for most Engineers this isn't always an option.
A greater sensible technique is to use a provider test reveal and a digital camera that you realize has been installation successfully to at least one volt top to top.
Put the video output from this examined camera into the test screen and modify the assessment and brightness until you are glad with the photo. Mark the evaluation and brightness controls so you can set them to this role once more.
Set up each digital camera adjusting the ALC (as above) then adjusting the LEVEL to attain a image just like that executed with the test digicam. (Making sure that your check reveal is ready on your marked positions)
NB: On maximum zoom lenses the ALC adjustment is a velocity manage for the Iris motor and is exceptional left within the mid function. The Amplifiers on Auto Iris lenses are touchy; so alter the LEVEL and ALC with a proper trimming tool instead of an everyday screwdriver, which can induce small voltages.

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Question thirteen. What Size Monitor Should I Be Using?

Answer :

The accurate size display is dependent on its use e.G. The range of images to be displayed at any given time, the viewing distance and the to be had space.

Question 14. What Is Video Termination?

Answer :

This is the give up of line resistance of any CCTV machine and this should be set to 75 ohm. Should you come upon any double photo or ghosting that is extra frequently than now not because of two pieces of system in series both having the seventy five-ohm switch set on. Only the closing piece of system should be set at seventy five-ohm.

Question 15. What Camera Housing Should I Use And At What Ip Rating?

Answer :

Camera housings are available diverse sizes and styles. With regard to the suitable IP score protection, this could variety from dust and water ingress. This gadget is governed with the aid of a number of European and British standards.

IP55:

Protected towards dust - constrained ingress.
Protection against low-stress jets of water from all directions - constrained ingress accepted.
IP655:

Protection towards low pressure jets of water from all instructions - limited ingress Permitted.
Question 16. What Is The Difference Between Simplex And Duplex Multiplexers?

Answer :

Video multiplexers are designed to allow recording of several cameras onto one recorder.

Simplex: 

A simplex gadget is satisfactory suitable to packages in which recording best is the priority. Simplex machines cannot show multi screen pictures (i.E. Quad, nine way and 16 way split) whilst inside the file mode.

Duplex:

If an operator is tracking the gadget (i.E. Safety protect) then a duplex system is greater suitable. A duplex system can provide screen splits and person selectable photos with out affecting what is recorded onto the recorder. Should you use  recorders, it will become viable to record and playback concurrently.

Question 17. Which Pan And Tilt Unit Should I Use?

Answer :

The choice is wide and varied dependent on the gadget requirements. You may additionally require Top mount, Side mount, 230V AC or 24V DC to call just a few.

TOP MOUNT:

Pro: Can suit two IR lamps at the side of the Pan/Tilt. These act as a counter balance permitting you to use a lighter responsibility Pan/Tilt head.
Pro: Compact length.
Con: Restricted tilt frequently -45 to zero dependent on the housing outfitted.
Con: Cannot be inverted.
SIDE MOUNT:

Pro: Can be inverted.
Pro: Often inexpensive.
Pro: Large tilt often +or- 180
Con: Difficult to mount IR lamps.
Con: Generally big length.
Question 18. What Type Of Illumination Can I Use With Color Cameras?

Answer :

Only lights within the seen wavelength need to be used with color cameras. Tungsten Halogen is frequently the advocated supply of lights.

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Question 19. Can I Use I/r Lamps With Color Cameras?

Answer :

The solution to that is a definitive NO. Color cameras are typically geared up with an IR cut clear out and will no longer allow IR light in extra of 700Nm to pass ensuing within the digicam appearing poorly in these situations.

Question 20. Do I Have To Use A Regulated Power Supply?

Answer :

In wellknown the solution is yes. Most producers will endorse using such strength elements as popular with their system. You must continually seek advice from the manufacturer’s specifications prior to the connection of any energy supply.

Question 21. What Is The Maximum Distance I Can Run 12vdc When Powering A Camera?

Answer :

This is a normally requested query and there is no simple solution. Some manufacturers may additionally propose that their cameras can be run over (X) distance with (Y) cable. This however need to still be considered as a trendy guide. Cable conductor size and set up course need to also be considered. If you're uncertain, we might recommend that you touch Technical Support for steering.

Question 22. What Is A Ground Loop?

Answer :

An AC modern-day that can be produced in a cable. This is commonly due to elements of the system being fed from exceptional electrical resources ensuing in special earth potentials at every quit. The end result is interference on the sign, commonly inside the shape of darkish bands across the screen and occasionally tearing within the top 1/3 of the picture.

Question 23. How Can I Eliminate Ground Loop Faults?

Answer :

This may be finished in a number of ways, the very best of that is the installation of a Ground Loop Isolation Transformer. This is quality set up on the monitor or recording stop of the device.

Question 24. What Is The Correct Level For A Video Picture?

Answer :

The correct stage is 1 volt peak to height. This can handiest be appropriately set both with an oscilloscope or with a video degree meter.

Question 25. Manual Or Auto Iris Lens?

Answer :

The iris is the a part of the lens that determines how a lot mild falls upon the digital camera CCD sensor.
The Manual Iris 'MI' lens has this constant on the time of installation. As the light stages trade within the scene, the lens can do not anything to prevent either too little or too much light getting into the digital camera. Virtually all cameras appoint an Automatic Electronic Shutter 'AES' to make amends for these variations when fitted with an MI lens. However they're handiest able to address a especially small exchange in mild levels.
An MI lens ought to in no way be used in an outside state of affairs, as the digicam might be not able to deal with massive modifications in mild stages. Use an Auto Iris ‘AI’ lens in this situation, or where massive scene illumination changes take location.
The advent of new sensor technology such as PIXIM might also bring about a alternate to this situation inside the future.