rf filter design
rf filter design
Glossary of Terms (M – R) – CCTV
EXPANSION RATIO
The relationship between the focal length of a lens and the focal length of a standard lens wide-angle. Indicates that the magnification of an image of a standard wide-angle lens.
MANUAL IRIS
Type of lens that requires manual focusing.
Switcher
Advanced switch type in which an input signal can be any connection to any number or combination of products. Mainly used in systems larger and more complex general matrix also incorporate a number of additional advanced features.
Microwave transmission
A method signal transmission through a microwave link frequency. Not affected by adverse weather conditions, but needs a direct line of site. The license may be necessary to operate a microwave frequency.
MODEM
Term derived from modulator-demodulator. A modem is used to convert analog and the digital signal and then transmit and receive signals through the PSTN.
PATTERN MEMORY
An adverse event that appears in the image when a model of HD video is often seen with a CCD camera that has a pattern of pixels large (but below) the object model.
Multiplex REGISTRATION video
The condensed recording of a video signal on a single tape or disk drive.
MULTIPLEX
The concept of transmitting signals multiple single channel.
MULTIPLEXER
A device that combines a number of signals into one. It is often used to describe closed-circuit a device that is mainly used to multiplex several video signals into one for purposes of registration or microwave transmission. It can also refer to a fiber optic multiplexer that combines a number of video signals into one to send them all through a single fiber cable.
N / CN ALARM E / S
It refers to the normally closed and normally open. It is generally used to describe the alarms CCTV.
NA
NA. A measure of acceptance angle of arrival of light in an optical fiber cable in the form of a cone. It is expressed as the square root of the difference of the squares of the indices of the core and the sheath.
NBS
National Bureau of Standards (USA).
ND FILTERS
neutral density filters are optical filters that attenuate the light a number times. This attenuation is equal for all wavelengths, therefore, does not change the color balance of an image, where the term neutral.
NIT
A photometric measurement unit of luminance. One nit is equal to one candela per square meter of projected area.
NOISE
An unwanted signal produced for all electrical circuits working above the absolute zero. The noise can not be eliminated but only minimized.
NTSC
National Television System Committee, an American committee that set standards for color television currently used in the United States, Canada, Japan and other countries.
O / P
Output. Objective. The first optical element in front of a lens.
OJO
The last optical element in the back of a lens (the close to the CCD chip).
OSCILLOSCOPE
(CRO also "cathode ray oscilloscope). An electronic device that measures changes in the signal over time. A must for all technicians of CCTV.
PAL
Stands for Phase Alternating Line, which describes the phase shift in a signal color PAL color.
Head tilt
(P / T head). A motorized unit permitting vertical and horizontal placement of a combination of camera and lens. Usually 24 VAC motors used in these P / T heads, but VAC 110, ie. 240 VAC units can be ordered.
PAN UNIT
mechanized unit that allows horizontal placement of the camera.
PHOT
A photometric light unit for very high levels of illumination. A photo of is equal to 10,000 lux.
PHOTODIODE
A type of semiconductor device in which a PN junction diode acts as a photo sensor.
Photo effect
Also known as the photoelectric effect. This is a phenomenon of ejection of electrons from a metal whose surface is exposed to light. Photon. A representative of the quantum nature of light. It is considered the smallest unit of light.
Photopic vision
The range of light intensities of approximately 105 lux 2.10 lux, detectable by the human eye.
Pinhole LENS
A primary objective for viewing through a very small aperture, used covert surveillance situations. The lens is usually focused unchecked, but offers a choice of iris functions.
PIXEL
Derived from the picture element. usually refers to the chip CCD camera cell phone unit. It consists of a photo sensor on the associated control gates.
Plumbicon
thermionic vacuum tube developed by Philips, with a layer of lead oxide photoconductor. He represented the ultimate imaging device for the introduction of CCD chips.
Filter Polarizing
An optical filter that transmits light in one direction (perpendicular to the path of light), 360 ° possible. The effect is such that it can eliminate areas unwanted reflections of light, like looking through a window. In photography, polarizing filters are often used to darken a blue sky.
POTS
Telephone Service conventional, ie. Phone service in common use today worldwide. Also known as PSTN.
PRESET POSITIONING
One of the functions a pan / tilt, including zoom, which can be a number of certain viewing positions stored in system memory (usually this is in the PTZ site driver) and recalled when needed, either a memory alarm trigger, programmed or manual.
START POINT
An optical term referred to one of the two points of each objective along the optical axis. The nearest point of principle of the imaging device (CCD in our case) is used as a reference for measuring the focal length of a lens.
PSTN
Switched telephone network is generally referred to "regular old phone" services. Also called POTS.
PTZ DRIVER SITE
(PTZ site receiver or decoder). An electronic device, usually a part a video switch matrix, which receives coded digital control signals to operate pan, tilt, zoom and focus functions.
QUAD COMPRESSOR
(Also split screen). Equipment that simultaneously displays parts or more than one image on a monitor. Usually refers to four quadrants display.
RAID
Redundant Arrays of Independent Disks. This technology of connecting a number of hard drives in a single mass storage device, which can be used, among others, to record digital video images.
RAM
Random Access Memory. An electronic chip, usually known as "memory" which have digital information, while the power is applied. Its capacity is measured in kilobytes.
INTERLACE AZAR
A term describing a camera that has the horizontal synchronization gear, instead of a guy who has blocked 2:1 interlace timing and therefore the two domains in a case exactly common.
REMOTE CONTROL
A transmission and reception of signals for controlling remote devices such as Pan / Tilt units the objective functions, wash and dry the control and the like.
RETMA
Former name of the Association EIA. Some older video graphics test is called "RETMA Chart.
The RF signal
radio frequency signal that belongs to the region up to 300 GHz.
RG-11
A video cable 75 ohm coaxial and a much thicker diameter than the popular RG-59 (approximately 12 mm). With RG-11 much longer distances can be achieved (at least twice the RG-59) but is more expensive and more difficult to work.
RG-58
A coaxial cable designed with 50 Ohms impedance, therefore not suitable for CCTV. Very similar the RG-59, only slightly weaker.
RG-59
A type of coaxial cable which is more commonly used in CCTV systems small and medium companies. It is designed with an impedance 75 ohms. It has an outer diameter of about 6 mm and is a good compromise between maximum distances achievable (up to 300 m for the signal black and white, and 250 m for color) and good transmission.
RMS
Abbreviation for Root Mean Square. All AC voltages are measured with multimeters which shows the rms signal (not vertices). For a sinusoidal signal, such as industry, the RMS value reaches 1.41 times (the square root of 2) then the values peak.
ROM
Read-only memory. An electronic chip that contains digital information that does not disappear when power is off.
RS232
A format of digital communication where only two children are needed. Also known as a serial data communication. The RS-232 standard defines a asynchronous communications system, but does not define how data should be represented by bits, ie. does not define the overall message format and protocol. It is often used communications between the keyboard and CCTV matrix switchers or between matrix switchers and PTZ site drivers. The advantage of RS-232 on the other lies in its simplicity and use of only two children.
RS422
This is an advanced format of digital communication via RS-232. The fundamental difference is the need for four instead of son two that communications are not as skewed with RS-232, but the differences. In simple terms, the signal is "read" at the end receive the difference between the child two, no common points. So if there is noise induced along the line, it will be canceled. The RS-422 can carry more data lines of a kilometer long and distribute up to 10 recipients.
RS485
This is an advanced format of digital communications compared to RS-422. The main improvement is the number of receptors that can be used with this format, up to 32.
About the Author
Instrom Limited is an independent security consultancy set-up in 1998 to provide a range of impartial security consultancy services to commerce, industry and the public sector. Business Security Consultants
Response to high-pass filter?
Problem: I have to have a section of a high-pass filter with a gain of 20 and a cutoff frequency 0.05. Calculate the response to an input of stage 1 mV. I tried to create a filter with Ri = 5kohm, Rf and Ci = 100kOhm 680microF So what do I do about the answer? I suppose the voltage, for example the frequency is equal to zero, taken in my office transfer? If this is the case, then I will have zero as my answer, which to me makes no sense … Thank you! May 5 Hz means. sad
You take Laplace transform of unit step function is 1 / s. The transfer function of the high-pass filter:-rf / (Ri + 1/SC) which is equivalent to (-SC) RF / ((SC) Ri 1) Multiply the transfer function of step 1 / SC (Rf) / ((SC) Ri 1) = – (Rf / Ri) / (s + 1 / (SRIC)) Take transformed Conversely Vout = – (RF / IR) (e ^ (-t / (ICN)) starts with a voltage Vout – Rf / Ri but exponential decay to 0
RLC Low-Pass Filter Design
