1. Do you know what Is A Ground Loop?
An AC current that can be produced in a cable. This is usually caused by parts of the system being fed from different electrical sources resulting in different earth potentials at each end. The result is interference on the signal, usually in the form of dark bands across the monitor and on occasion tearing in the top third of the image.
2. Tell me what are some of your strengths on the job?
Prepare an answer that emphasizes the skills and requirements outlines in the job listing. Match your abilities to the company's needs and goals, and focus your reply on what makes you stand out from the competition.
3. Tell us what Type Of Illumination Can I Use With Color Cameras?
Only lighting within the visible wavelength should be used with color cameras. Tungsten Halogen is often the recommended source of lighting.
4. Tell us how comfortable are you using computers?
As a security guard, you'll have to use the software associated with CCTV cameras. If you have experience using CCTV equipment, say so. Otherwise, demonstrate computer literacy and an ability and willingness to learn to use new systems.
5. Explain me what Size Monitor Should I Be Using?
The correct size monitor is dependent on its use e.g. the number of images to be displayed at any given time, the viewing distance and the available space.
6. Please explain do I Have To Use A Regulated Power Supply?
In general the answer is yes. Most manufacturers will recommend the use of such power supplies as standard with their equipment. You should always consult the manufacturer's specifications prior to the connection of any power supply.
7. Can you tell me what Is The Correct Level For A Video Picture?
The correct level is 1 volt peak to peak. This can only be accurately set either with an oscilloscope or with a video level meter.
8. Explain me how Do I Connect An Auto Iris Lens To A Camera?
This is usually performed by a simple plug-in connection to the rear or side of the camera. However you should always refer to the relevant camera handbook.
9. Tell us what could cause one to quit working?
Lack of power, broken or damaged internal wires, corroded connectors or improperly assembled connectors can likely cause this to happen. The best recourse is to troubleshoot and find out the exact cause of the problem to repair as needed.
10. How To Eliminate Ground Loop Faults?
This can be achieved in a number of ways, the easiest of which is the installation of a Ground Loop Isolation Transformer. This is best installed at the monitor or recording end of the system.
11. Tell me when Can I Use A Manual Iris Lens?
A general rule of thumb is only to use a MI lens in an internal application. This is because you are reliant on the electronic circuitry of the camera compensating for light changes in the scene and this is not able to compensate to the same degree as that of an Auto Iris lens.
12. Do you know what Is The Difference Between Auto Iris And Direct Drive Lenses?
☛ An Auto Iris lens is one that automatically adjusts its iris for changes in the scene lighting levels. The motor that opens and closes the iris is driven by an Amplifier that processes a small electronic signal changing with the light level.
☛ A Direct Drive 'DD' lens does not have this Amplifier and can only operate with a camera fitted with one.
☛ A camera specification will indicate the available output options.
13. Tell me how to stop one from rotating 100 degrees left and right automatically?
Turn off the ‘Auto Panning' feature on your device and see if it solves the problem. If not, the unit itself could be at fault that will need to be replaced.
14. Can you tell me what Is The Maximum Distance I Can Run 12vdc When Powering A Camera?
This is a commonly asked question and there is no simple answer. Some manufacturers may recommend that their cameras can be run over (X) distance with (Y) cable. This however should still be considered as a general guide. Cable conductor size and installation route must also be taken into consideration. If you are unsure, we would recommend that you contact Technical Support for guidance.
15. What is software Compression?
The DVR Board only capture video signal but doesn't compress it, it is the computer CPU and RAM to do this compression work. It's high cost of CPU and RAM resources. In this system the computer CPU and RAM are often overloaded. It is easier to crash than hardware compression system.
16. Tell us how to install a camera IR24W with a TV monitor?
First, check if the device has a BNC connector and the CCTV uses an RCA input. If so, connect the BNC cable to the RCA jack on the monitor; otherwise, plug the RCA camera to the BNC input. Then, push the ‘Source' button on the remote control to select the input ‘Composite' on the TV. Finally, make sure there is power to the camera to see the video.
17. Can you tell me how Do I Back Focus A Camera Fitted With A Fixed Focal Length Lens?
This is achieved by following five simple steps:
☛ Set the physical focus of the lens to infinity (clockwise from the front).
☛ Aim the camera at the subject to be viewed.
☛ Release the camera back focus mechanism.
☛ Adjust the back focus to obtain the best possible picture.
☛ Secure the cameras back focus mechanism.
18. Tell us what Camera Housing Should I Use And At What Ip Rating?
Camera housings come in various shapes and sizes. With regard to the correct IP rating protection, this will range from dust and water ingress. This system is governed by a number of European and British standards.
IP55:
☛ Protected against dust - limited ingress.
☛ Protection against low-pressure jets of water from all directions - limited ingress permitted.
IP655:
☛ Protection against low pressure jets of water from all directions - limited ingress Permitted.
19. Explain me a time when you used teamwork to solve a problem at a previous security job?
If you don't have prior experience in security, talk about how you used team-based problem-solving in some other type of position.
20. Tell me how to wire one to get an RG59 BNC connection?
☛ Connect the red wire to red and the white wire to the black wire of the camera.
☛ Make sure the red and white wires are positive and negative.
☛ Then, insert the solid or center copper wire of the RG59 to the unit's yellow video line.
☛ Finally, connect the braided shield of the RG59 to the black ground wire of the camera.
When setting the back focus of a Color camera for low light conditions you should place an ND1 (Neutral Density) filter in front of the lens. When setting the back focus of a Mono camera for low light conditions you should place an ND3 (Neutral Density) filter in front of the lens. When setting the back focus of a Mono camera fitted with I/R lighting for low light conditions you should place an IRP (Infra- Red Pass) filter in front of the lens.
22. Explain me which Pan And Tilt Unit Should I Use?
The choice is wide and varied dependent on the system requirements. You may require Top mount, Side mount, 230V AC or 24V DC to name just a few.
TOP MOUNT:
☛ Pro: Can fit two IR lamps on the side of the Pan/Tilt. These act as a counter balance enabling you to use a lighter duty Pan/Tilt head.
☛ Pro: Compact size.
☛ Con: Restricted tilt often -45 to 0 dependent on the housing fitted.
☛ Con: Cannot be inverted.
SIDE MOUNT:
☛ Pro: Can be inverted.
☛ Pro: Often cheaper.
☛ Pro: Large tilt often +or- 180
☛ Con: Difficult to mount IR lamps.
☛ Con: Generally large size.
23. Please explain about a time you successfully dealt with an angry member of the public?
This question is focused on your ability to encounter anger without becoming emotionally triggered yourself and without resorting to violence. A successful outcome in this context involves pacifying the angry person and resolving the situation. If you've ever worked in any kind of customer service role, you'll have something to share. Just remember to focus on the outcome and what it says about your skills and abilities, rather than getting bogged down in telling a funny (or horrifying) story.
24. Basic CCTV Operator Job Interview Questions:
☛ Examine these 2 pictures of 2 different people for a couple of seconds. Then, put the photographs down, and describe those 2 people to me.
☛ Tell us about how you have worked in a team to solve a problem in a former security job?
☛ If you witness an attack, how would you handle the situation?
☛ Tell us about a time when you successfully dealt with an aggressive customer without using physical force, describe what words and gestures you used to defuse the situation?
☛ How do you feel about using computers, do you use one at home if so what for?
☛ Are you currently First Aid trained and certified?
☛ Describe a time on the job when you felt as if you were about to be physically attacked. How did you handle the situation?
☛ If you found out a fellow security officer was perusing information he/she shouldn't be, but in your opinion the information wasn't that important anyway, what would you do?
☛ If you are working at an event where there is a large and disorderly crowd, what measures could you take to make sure the event does not become too unruly or hazardous?
☛ Imagine you have been called to handle an emergency on the 12th floor of a building, but eight guests are waiting to be checked in at the front desk. It's late at night and you are alone at the front desk. How would you deal with the situation?
25. Tell us what is The Difference Between Hardware Compression And Software Compression?
☛ Hardware Compression: 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.
☛ Software Compression: The DVR Board only capture video signal but doesn't compress it, it is the computer CPU and RAM to do this compression work. It's high cost of CPU and RAM resources. In this system the computer CPU and RAM are often overloaded. It is easier to crash than hardware compression system.
It is all right to discuss an assault that you experienced in your personal life, if you have never encountered one professionally. If you have never experienced an assault, do not make one up, but you can ask whether describing a hypothetical situation would help.
This is due to the depth of field changing as the light conditions change and can be easily overcome by following set procedures.
28. Explain me about a time when your trustworthiness was challenged. How did you respond?
I haven't ever been questioned on my trustworthiness, but if I did, I would cooperate fully and give everyone anything that they need to complete an investigation. I know that they'll need concrete details, so I'll do my best to give them this kind of information. I wouldn't take it personally because it's our job to maintain integrity and do our due diligence.
29. Tell us what components would need to be checked before connecting a CCTV camera to a TV?
☛ First, make sure the camera channel or the RF modulator use a channel that has no local TV station.
☛ Then, check the level of power output on the modulator and accordingly, use a coaxial cable to connect the RF output to the input on the booster.
☛ Next, measure the input on the booster and depending on the input, use a mixer to feed the coaxial output of the RF modulator.
☛ Finally, if the booster appears to be a split type and your TV channels receive signals through aerial connection, then using a pass through type of mixer will be recommended.
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.
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.
32. Tell me how Do I Set Up An Auto Iris Lens?
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.
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.
34. Explain me if one fails to display the image on a large screen despite a good signal?
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.
35. Tell us are you currently CPR/First Aid/AED certified?
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.
