“CCTV Operator Frequently Asked Questions in various CCTV Operator job interviews by interviewer. The set of questions are here to ensures that you offer a perfect answer posed to you. So get preparation for your new job interview”
Both Capturing Video Signal and Compressing Video Signal are done by DSP chipset integrated on DVR Board. It doesn't need the computer's CPU to do this work. It's low cost of CPU and RAM resources. In this system the computer CPU's task focus on answering network request, streaming the video/audio to network and saving recorded data to local hard disk.
OSD (On Screen Display) cameras have a menu system within the camera assembly that can be accessed in order to set functions such as Iris levels, AGC on/off and most features of standard and advanced cameras.
Yes, lenses are usually specified as having a minimum and maximum 'f' stop rating; the 'f' stop is a measure of how efficiently the lens allows light from the scene, to pass through the lens and onto the camera CCD sensor. The maximum aperture (when the lens is fully open), is the minimum 'f' stop number and the minimum aperture, (just before the lens completely closes) is the maximum 'f' stop number.
A low minimum 'f' stop number means that the lens can pass more light through during dark conditions, which will produce better pictures at night.
A high maximum 'f' stop number may be necessary where there is a high level of light or reflection. This will prevent the camera ‘whiting out’.
This is the end of line resistance of any CCTV system and this should be set to 75 ohm. Should you encounter any double image or ghosting this is more often than not caused by two pieces of equipment in series both having the 75-ohm switch set on. Only the last piece of equipment should be set at 75-ohm.
The answer to this is a definitive NO. Color cameras are typically fitted with an IR cut filter and will not allow IR light in excess of 700Nm to pass resulting in the camera performing poorly in these circumstances.
Security guards have little to do during periods when no threat occurs -- the job is mostly to be on hand in case something happens.
Your interviewer will want to assess whether you are likely to become distracted or even cause trouble during these periods. Tailor your answer to show that you’re able to react quickly when required.
The best option is to connect a USB video capture adapter to the machine and then, use a standard BNC to RCA adapter to convert the plug from the camera.
Using a thick paper or your finger, cover the unit’s light sensor. This will activate the night mode in the device. If the night vision LED appears to glow, then the camera is receiving power and recording. Additionally, check for a clicking sound from the Auto Mechanical IR Cut Filter on the camera for further confirmation.
The best way is to feed the ‘Video Out’ on the camera to the ‘Video In’ on the VCR or DVD recorder using a video modulator or a Scart adapter:
Video Modulator:
☛ Connect the ‘Video Out’ on the camera to a mini TV transmitter.
☛ Then, tune the receiver to the channel outputted by the modulator to get the camera’s signal as a regular TV channel or station.
Scart Adapter/Converter:
☛ Route an RCA to RCA cable from the camera to the receiver.
☛ Then, connect the RCA to the adapter.
☛ Finally, insert the adapter to the top ‘Scart’ input to record the video.
I do have an interest in criminal justice. I get upset when I see people getting away with crime, and I see my job as a surveillance operator as one way to try to prevent that. The cameras are always going to be recording everything, but it's up to me to monitor the video feed and report any suspicious activity. I also have to provide solid documentation because this might be used in an investigation from law enforcement. They don't have time to watch hours of footage, they depend on me to point them in the right direction. Criminal justice is very interesting to me and I want to be a part of the system.
☛ This in general is a comparatively difficult decision. Many aspects of the installation must be taken into consideration in order to obtain the correct performance that meets your requirements.
☛ A high-resolution camera should be considered where greater detail of scene is required. E.g. Color 460 TVL, Monochrome 570 TVL. Choosing a more sensitive camera will improve reproduction in poorly lit areas. The sensitivity of a camera is indicated by the minimum amount of light in order for the camera to produce a usable picture. e.g. Color 1.0 Lux at F1.2.
☛ A conventional camera produces a pale backdrop when an object is shot against a bright background. BLC (Back Light Compensation) will counter strong light sources retaining picture quality.
☛ Concentrated light sources directed towards the camera (e.g. car head lamps) can be inverted by an optional peak white inverter or an eclipse function. This has the effect of bringing detail to areas and making an object clear, that would otherwise be shadowed.
This can be achieved by following these steps:
☛ Set the lens to full wide angle view.
☛ Set the physical focus of the lens to infinity (clockwise viewed from the front).
☛ Aim the camera at an object at least 30 Meters away.
☛ Release the camera back focus mechanism.
☛ Adjust the back focus to obtain optimum clarity.
☛ Zoom the lens in to full telephoto and focus on a nearby object.
☛ Keep this object in view as you slowly zoom out and if all is set correctly it should remain in focus (track).
☛ Secure the back focus mechanism.
Video multiplexers are designed to allow recording of several cameras onto one recorder.
Simplex:
A simplex machine is best suited to applications where recording only is the priority. Simplex machines cannot display multi screen images (i.e. quad, 9 way and 16 way split) while in the record mode.
Duplex:
If an operator is monitoring the system (i.e. security guard) then a duplex machine is more suitable. A duplex machine can provide screen splits and user selectable images without affecting what is recorded onto the recorder. Should you use two recorders, it becomes possible to record and playback simultaneously.
☛ The iris is the part of the lens that determines how much light falls upon the camera CCD sensor.
☛ The Manual Iris 'MI' lens has this fixed at the time of installation. As the light levels change in the scene, the lens can do nothing to prevent either too little or too much light entering the camera. Virtually all cameras employ an Automatic Electronic Shutter 'AES' to compensate for these variations when fitted with an MI lens. However they are only able to cope with a relatively small change in light levels.
☛ An MI lens should never be used in an external situation, as the camera will be unable to cope with large changes in light levels. Use an Auto Iris ‘AI’ lens in this case, or where large scene illumination changes take place.
☛ The advent of new sensor technology such as PIXIM may result in a change to this situation in the future.
This question will warrant a “yes” or “no” answer, although you can feel free to mention if you’re currently enrolled in a class and working toward achieving certification.
It’s also a good reminder to familiarize yourself with the general requirements of a job when you begin interviewing. Your research will tell you what skills are expected for someone in this role.
The best recourse is to configure the unit properly to display the correct resolution. However, if the problem still persists, the unit could be faulty and will need to be checked.
Immediately I'd write down the details: a description of the person, the location of the incident, the date and time, and the item that I observed was being concealed. I would immediately report it to my supervisor.
An Auto Iris lens has two 'pots' on the side commonly marked ALC (Automatic level control) and LEVEL.
The ALC control has settings of PEAK and AVERAGE (P+A).
The LEVEL control has HIGH and LOW settings 'H+L'.
ALC:
☛ The adjustment allows control over any bright areas in the scene e.g. sun reflection through windows, street lighting etc. There are two settings PEAK and AVERAGE.
☛ If set to PEAK, bright areas in the scene are taken into account more, reducing the contrast in the surrounding area. This allows more detail to be seen in the bright areas.
☛ If set to AVERAGE the lens takes the bright areas less into account which usually causes over brightness or flare in these areas, but raising the contrast of the surrounding area.
LEVEL:
☛ The only correct way to set the VIDEO LEVEL is by the use of an oscilloscope, for most Engineers this is not an option.
☛ A more practical method is to use a service test monitor and a camera that you know has been set up correctly to 1 volt peak to peak.
☛ Put the video output from this tested camera into the test monitor and adjust the contrast and brightness until you are satisfied with the picture. Mark the contrast and brightness controls so that you can set them to this position again.
☛ Set up each camera adjusting the ALC (as above) then adjusting the LEVEL to obtain a picture similar to that achieved with the test camera. (Making sure that your test monitor is set to your marked positions)
NB: On most zoom lenses the ALC adjustment is a speed control for the Iris motor and is best left in the mid position. The Amplifiers on Auto Iris lenses are sensitive; so adjust the LEVEL and ALC with a proper trimming tool instead of an ordinary screwdriver, which can induce small voltages.
If you have never felt threatened at work, ask if you should discuss a threat encountered in your private life. Ideally, these threats should have come from other people, because your answer is supposed to indicate how you will respond to threats in your work as a guard. If you have never felt threatened by another human being, ask if some other form of danger (an earthquake, for example) might be considered relevant.
Place a polarizer filter on the front of your unit’s lens and see if it fixes the issue. If not, use a neutral density filter along with the polarizer filter and place one filter atop the other on the front of the lens.
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