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FAQ: GigE Vision standard interface

Q: What is the maximum cable length of a Gigabit Ethernet connection?
A:
Cable lengths of up to 100 meters are possible. Longer distances can be bridged using switches or routers.

Q: What type of cable is required for GigE Vision cameras?
A:
Cat5e can be used, but Cat 6 is recommended

Q: How can I avoid trigger latency with GigE Vision cameras
A:
All JAI GigE Vision cameras accept a hardware trigger (in the 12-pin Hirose connector), providing no-delay triggering.

Q: How many cameras can I connect to one GigE Vision host.
A: In theory, GigE Vision allows an infinite number of cameras to be connected. In practice, however, the number of cameras depends on the transmission rate (MByte/sec) being sent from each camera; Image resolution x frame rate = transmission rate. The maximum transmission bandwidth is 125 Mbyte/sec.

Q: Which Gigabit Ethernet devices can I use together with the GigE Vision cameras?
A:
All network switches designed for Gigabit Ethernet can be used. When using Jumbo packets, make sure to use a switch that can handle more than 1.5kB packets

Q: What is a Jumbo packet?
A: An Ethernet data packet larger than 1440 Bytes is loosely referred to as a Jumbo packet. Using Jumbo packets improves the transmission throughput, as the overhead (packet headers) is reduced.

Q: Does JAI provide software with the cameras?
A:
Yes, JAI provides the necessary drivers and other DLL files for WinXP. There also an SDK (Software Developent Kit) for the cameras, allowing the system engineer to easily integrate the cameras in the application

Q: What is GenICam?
A:
GenICam is a standard associated with the GigE Vision standard, defining a generic interface for controlling cameras in conjunction with an XML file

Q: What is an XML file?
A:
It is a standard file format used to describe the functions available to a particular camera. The XML file resides in the camera and is downloaded to the Host when the camera is connected. The host software is then automatically configured with the functions (and range of settings of the functions) for precisely this camera.


 

 FAQ: General questions

Q: How do I get HD/VD output from Analog cameras?
A:
This can be done by internal SW setting, please consult the user's manual.

Q: Can I view the image from the CV-M10SX on a monitor?

A: Unlike the CV-M10BX/RS, the CV-M10SX does not support an interlaced mode. It is therefore not possible to view the image on a video monitor.

Q: Does JAI manufacture cameras for infrared light?
A:
The EXview sensor used in CV-M50IR is sensitive in the near infrared and therefore useful using artificial light with a high amount of infrared light. In general, CCD sensors are sensitive to near infrared light and can be used for e.g. surveillance. JAI Camera Solutions does not make cameras sensitive to mid- and far infrared light.

Q: Does the CV-M10 camera supply a VD pulse and vertical sync. signal when operating in Random Trigger Mode?

A: No. You need to use the WEN pulse (pin no.: 6) on the 6 pin Hirose plug.

Q: How can I control the long time exposure in analog
output cameras?
A:
By applying external VD pulses. The exposure time is the time span between two VD pulses. It is recommended that the maximum exposure time of two seconds is not exceeded.

Q: How can I reduce jitter when triggering the camera?

A: By synchronizing the trigger pulse to HD.

Q: What is the minimum and maximum duration for the trigger signal?
A:
A trigger pulse greater than one HD (i.e. 64 µsec.), with a maximum duration of 1 msec can be applied to the camera.

Q: What is the minimum and maximum duration for the trigger signal?
A:
A trigger pulse greater than 2µsec., with a maximum duration of 1msec can be applied to the camera   

Q: How do I get access to the pixel clock output?
A:
This can be done by internal jumper setting, please consult the user manual.

Q: How does the CV-A11 indicate start of valid video to the frame grabber?
A:
This is indicated by the leading edge of the WEN pulse.
Q: How long delay can be used in frame-delay readout?

A: In principle the delay can be long, but it is recommended not to exceed two seconds. The stored image is distorted by the "dark current" image caused by leakage in the pixels.

Q: How often can I trigger the CV-M10?
A: The read-out of the previous exposure must be completed before sending a new trigger pulse to the camera.
Q: How to get a video signal for controlling the auto-iris lens aperture?

A: Some cameras have a separate video output signal, which can be used directly for controlling an external auto iris lens system. For other cameras, a modification is needed either internally or externally. Please note that this will only work in continuous mode. Make sure to buffer this output, as it may otherwise affect the overall image quality.

Q: How to install an IR-cut filter?

A: For most JAI cameras the IR-cut filter is mounted in a filter ring. This filter ring is mounted in the C-mount thread of the camera.

Q: Can I get the full resolution out of an interlaced camera when triggering?

A: Normally interlaced cameras (TV-standard) will only allow one field to be captured when triggered. It is, however, possible to capture both fields in trigger mode when a strobe light (LED flash, Xenon flash) is used as illumination. The shutter must be set to OFF, and the camera set to frame mode. Contact JAI for an application note on how to operate in this mode.

Q: Is long time exposure possible on the CV-M10?

A: Yes. There are eight pre-defined steps from 2-16 fields (1 field equals: EIA: 1/60 sec., CCIR: 1/50 sec.). This only works in continuous mode.

Q: What are the advantages of using an RGB output camera like the CV-M91?

A: An RGB camera provides 3 primary colors on three different channels, thus no information is lost. The result is superior color reproduction at full resolution.

Q: What does progressive scan mean?

A: Quite simply, progressive scan means that the picture information is accumulated simultaneously and then output line-by-line or sequentially. The result is a non-interlace image with full vertical and horizontal resolution captured in a single rapid shutter event.
Traditional interlace CCD cameras are only capable of capturing one field, or half the vertical information, per shutter event because the scan function breaks the integration period into two sequential field scans. In dynamic image capture, by the time the second field of information is stored and scanned the subject already has moved. The result is a ghosting or blurring effect once the two scan periods are combined to create the whole, interlaced picture. Interlaced images of even static objects can introduce some noticeable "jitter". This is successfully eliminated with progressive scanning.

Q: What is a multiple shutter function?

A: A multiple shutter function allows multiple exposures within the same image frame. It can be used for studies of very fast movements. The multiple exposures are done by adding the charge from triggered accumulations into the stopped vertical CCD register. After last exposure the resulting image with multiple exposures on top of each other is read out.

Q: What is an IR-cut filter?

A: "An IR-cut filter is a color filter blocking the infrared light. There are several good reasons for using an IR-cut filter. All JAI color camera include an IR-cut filter in order to achieve proper white balance and realistic colors. Monochrome cameras are sometimes equipped with an IR-cut filter, to block out unwanted energy from light sources inclucing longer wavelengths (typically above 600 nm). Such light sources may be halogen tungsten lamps or even the sun. Reducing the IR contents in monochrome cameras helps improve the MTF (Modulation Transfer Function) which results in sharper images, allowing cameras to visualize finer detail."

Q: What is asynchronous accumulation?

A: If the accumulation starts immediately on the leading edge of the trigger without any delay, it is called asynchronous accumulation.

Q: What is binning and what is the advantage of binning?

A: Binning is a read-out method where the charge from more adjacent pixels are added together and read out as a single pixel. In horizontal binning adjacent pixels in the same line are added together. In vertical binning adjacent pixels in the same column are added together. In some JAI cameras, a combination of both is used. The advantage of binning is a higher read-out frame rate, and a higher sensitivity. With both H and V binning, the image aspect ratio is correct. The resolution for a two-to-one binning will be 50%.

Q: What is frame-delay readout?

A: Frame-delayed readout makes it possible to make a triggered accumulation and delay the resulting image readout. A trigger pulse will initiate the accumulation, and an externally applied VD will start the readout. It can be useful in applications with more cameras triggered at different time and readout at the same time. Or if more cameras are triggered at the same time, and the resulting images are read out in sequence to a single input frame grabber.

Q: What is H synchronous accumulation?

A: If the accumulation in triggered mode does not start immediately at the trigger leading edge, but starts at the first HD pulse hereafter, it is called H synchronized accumulation. If the trigger and HD are not synchronized, a delay (or jitter) of < =1H can be expected

Q: What is smearless readout?

A: Smear is caused by an unwanted charge build-up in the CCD vertical registers during the time before the actual shutter time and during the readout time. In smearless mode the smear level can be reduced, if the CCD is read out with a high speed just before the actual triggered shutter time. It will reduce the smear effect above the highlighted areas. Below there is no reduction. In smearless mode, the trigger will start this dummy readout before the accumulation starts, causing a small delay.

Q: What is the difference between an analogue camera and a digital camera?

A: In analogue cameras a limited bandwidth and propagation delay can cause a reduction in the image quality. It is not sure that the content from a sensor pixel is placed in the display byte without any cross talk from the adjacent pixels. In a digital camera the contents from the sensor pixels are transferred to the display bytes without any distortion.

Q: What is the ideal lens setting for minimum color shading?

A: When talking about 3CCD cameras, "chromatic shading" generally means unequal color reproduction from top to bottom. Please use a F-number higher than 4.0. Furthermore, avoid using high shutter speeds (i.e., short shutter times).

Q: What is the tolerance of the optical axis (in relation to the position of the CCD)?

A: For these C-mount cameras the X, Y axis direction is < ±0.1mm (i.e. the center of the sensor in relation to the center of the C-mount).

Q: What is the maximum trigger delay from trigger input to start of exposure?

A: With internal synchronization the delay can be up to one HD.

Q: What kind of lenses can I use with the CV-M91 3CCD camera?

A: Use only lenses specially designed for 1/3" 3CCD cameras. Please contact your local dealer.

Q: Why do I experience amplitude differences between field 1 and field 2 in long time integration or random trigger mode?

A: As the video output is AC coupled, a random video output will cause a difference between the fields if the connected systems lack DC-restoration. The output can be modified to DC output. Please contact JAI.

Q: What is Partial Scan?

A: Partial scan is a readout mode, whereby only a part of the CCD is read out. The remaining lines are "fast dumped" out of the image sensor and ignored. This results in a higher frame rate, with reduced vertical resolution. Typically, partial scan is defined as 1/2, 1/4, 1/3, 1/8, etc. of the full resolution, located in the middle of the imager. Some camera models have user selectable start position and number of lines in partial scan. CMOS imagers also allow partial scan, where a region of interest can be defined both in the vertical and horizontal direction. This is normally referred to as windowing.

Q: What is meant by "readout mode"?

A: This is the definition of modes of operation, whereby the readout (scanning) of the image sensor deviates from the standard operation. Examples of readout modes are "binning", "partial scan", "frame-delay readout", "readout inhibit"

Q: How can I easily see which camera(s) use a particular image sensor?

A: Use the search function of the web site. E.g. type in an image sensor, for instance ICX285, and all cameras built around this imager will be listed.

Q: What is smear?

A: Smear refers to an unwanted artefact in the image, showing up as a vertical stripe (vertical streak) from the top down to the bottom of the image, emanating from the bright parts of the image. The reason for smear in interline transfer CCD sensors is the scattering of light into the vertical shift register during the readout phase. Shorter shutter times make smear more obvious. Using strobed light sources can eliminate smear, so that no light is hitting the image sensor during readout. Implementing special readout modes can reduce smear.

Q: What is blooming?

A: Under conditions where a CCD is exposed to very strong light, the storage capacity of the pixels may be exhausted and subsequently become saturated. The excess charge that cannot be held within the pixel spills over to neighbouring pixels. When bloomed, bright spots in the image show up as completely white blobs.

Q: What is PIV (P.I.V.)?
A:
PIV stands for Particle Image Velocimetry. It is a technique for measuring and recording instantaneous velocity vectors in a cross-section of a flow. Two velocity components are measured. By using a stereoscopic approach all three velocity components can be recorded, which results in 3D velocity vectors for the whole area. CCD cameras capable of capturing two images with extremely short inter-frame time (in the range of a few microseconds). Used together with specialized computer tools, the images result in real-time velocity maps.

Q: What is the distance between the lens and the sensor for C-mount?

A: The so called flange focal distance is 17.526 mm for C-mount lenses. This is the distance from the reference shoulder to the CCD image sensor surface. The actual distance from the last lens element to the CCD varies depending on lens design and focal distance.

Q: Which Gigabit Ethernet devices can I use together with the GigE Vision cameras?

A: All network switches designed for Gigabit Ethernet can be used. When using Jumbo packets, make sure to use a switch that can handle more than 1.5kB packets

 
 
 

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