QUALIMATEST - System Integrator in VISION and AUTOMATION

English | Deutsch | Français

NEWS

News

Newsletter

17.05.2004
QUALIMATEST on the TV

The Swiss National TV came in the QUALIMATEST office

Play the movie >>

Nl Honors 15 Alliance Program Members

NEWS RELEASE – March 1, 2005 – National Instruments today recognized 15 out of the more than 500 companies in the National Instruments Alliance Partner program as Select Alliance Partners for 2005. Alliance Partners use their application expertise and in-depth knowledge of National Instruments products to build customer-defined solutions in a wide range of industries and applications including aerospace/defense, automotive and manufacturing test. NI reserves the Select Alliance Partner category for distinguished members of the Alliance Partner program who have established a high level of business, commitment to an ongoing relationship with NI and professional business practices.

2005 Americas Select Alliance Partners:

· Advanced Measurements, Inc. (Canada)
· B&B Technologies, Inc.
· Bloomy Controls, Inc.
· Cal-Bay Systems, Inc.
· DAQTron, Inc.
· VI Engineering, Inc.
· Viewpoint Systems

2005 Europe/Asia Select Alliance Partners:
· Alfautomazione (Italy)
· AmFax (United Kingdom)
· Goepel (Germany)
· Konrad Technology (Germany)
· MeasX (Germany)
· MicroLEX (Denmark)
· Peritec (Japan)
· Qualimatest (Switzerland)

“National Instruments is pleased with the continued growth of our existing Select Alliance Partners as well as our new additions, particularly internationally,” said Pete Zogas, NI senior vice president of sales and marketing. “With the Select Alliance Partner distinction, our goal is to identify best-of-class partners around the world and in various industries that we can recommend to our customers to develop their most challenging applications.”

All Select Alliance Partners work closely with National Instruments worldwide sales, marketing, R&D and technical support organizations to choose and integrate the best products to ensure customer satisfaction. Select Alliance Partners also demonstrate ethical business practices, a commitment to customer success and financial stability.

For more information about the Alliance Partner program and Select Alliance Partners, readers can visit www.ni.com/alliance .

01.03.2005
National Instruments Names Select Alliance Partners for 2005

For years pattern matching has been a machine vision staple in applications that detect, count, align, or inspect objects. National Instruments pattern matching is based on highly optimized cross-correlation algorithms that use stable pixel regions and edge information within an image to accurately locate matching templates down to one-tenth of a pixel and one-tenth of a degree. However, you may have difficulty using cross-correlation-based pattern matching to match templates that are overlapping or scaled to different sizes.

With the new Vision 7.1 Development Module, you can use a new matching tool called geometric matching to solve these more complicated vision application challenges. Geometric matching is a powerful algorithm for finding and sorting overlapping objects that are only partially visible, for matching components that contain distinct geometric information, and for guiding robots when objects in the field of view change scale as a camera moves closer to and further from them.

Pattern matching and geometric matching are both two-step processes. The first step is to learn a template and the second step is to search for a match to the template within an image. In correlation-based pattern matching, the learning step extracts large areas with similar pixel values and sharp edges to create a simplified model that speeds up the search. Geometric matching also builds a model of the template in the learning step, but rather than look for stable pixel regions and edges, it looks for 2D shapes such as circles and rectangles, linear primitives such as parallel lines, and other distinct geometric features such as corners and curves. The second step in both algorithms uses the abstracted templates from the learning step to search for a match in the image.

These two algorithms cover a wide range of matching applications and scenarios. Correlation-based pattern matching is effective in general matching applications for which features are defined by their grayscale values or textures. Examples are prevalent when inspecting consumer packaging and labels for cosmetic defects. You cannot easily define these labels, which often contain complex patterns or many shades of gray, by geometric shapes. Geometric matching works best when you are defining objects by geometric components such as stamped metal parts moving down an assembly line. With geometric matching, you can identify, locate, and sort these metal parts even if they are overlapping, dirty, or reflecting glare. Learn more about NI vision algorithms and request an evaluation copy of the NI Vision 7.1 Development Module.

01.03.2005
NI Vision Debuts New Geometry-Based Matching Tool

NEWS RELEASE - Feb. 8, 2005– National Instruments today announced several new image acquisition boards for machine vision and scientific imaging, including the new NI PCI-1426 low-cost image acquisition board for base-configuration Camera Link cameras. The PCI-1426 is the newest NI image acquisition board in a suite of digital and high-performance Camera Link image acquisition devices.

The PCI-1426 board features onboard image binarization, 16 MB of onboard memory and an optically isolated 15-pin D-Sub connector for camera triggering and system synchronization. Delivering an affordable solution for base-configuration Camera Link cameras, the new PCI-1426 completes the suite of NI Camera Link image acquisition boards. The suite includes the NI PCI-1428 image acquisition board for medium-configuration Camera Link cameras and the NI PCIe-1429, the industry’s first PCI Express frame grabber, for full-configuration Camera Link cameras. The PCI-1426, PCI-1428 and NI PCIe-1429 boards are ideal for both high-speed, industrial inspection applications and high-resolution scientific imaging applications.

Additionally, NI released two new analog image acquisition boards, the high-performance NI PCI-1410 and the low-cost NI PCI-1405. The monochrome, four-channel PCI-1410 offers support for nonstandard analog cameras and eliminates the need for extra synchronization signals to acquire nonstandard images. The PCI-1405 is a low-cost, color image acquisition board that is ideal for applications such as security monitoring.

08.02.2005
National Instruments Expands Suite of Camera Link Image Acquisition Boards

VISION 2004, Stuttgart, 19. - 21. October 2004 - Sony Europe's Image Sensing Solutions division held the company's first public preview of its forthcoming IEEE1394b cameras. The Sony on-stand demonstration included a pre-release sample version of the forthcoming XCD-V50 camera linked by an IEEE1394b 800mbps link to a VAIO PC equipped with a 1394b interface board. The camera was monitoring a moving AIBO (Sony robotic dog) to demonstrate the capturing of live images in full resolution (VGA), and full speed (60fps).

Sony expects that the adoption of the new revision of the standard is likely to ensure that IEEE1394 will remain the solution of choice for industrial vision applications. It will allow Sony, which pioneered the use of IEEE1394 in industrial image sensing products, to bring new levels of functionality and performance to its customers.

Sony is expected to lead the way as it did with IEEE1394 version 'a' cameras for the machine vision market. The company's first IEEE1394b camera, the XCD-V50, is planned to be a VGA monochrome model based on a 1/3-type CCD, support 60fps and 800Mbit/s throughput, and include added functionality with extremely low power and small size. Other expected features consist of full IIDC compatibility including hard and soft trigger, shutter control and gamma correction. A raw colour model is expected to follow soon after.

The XCD-V50 is expected on the market in early 2005, with a full range of Sony IEEE1394b cameras to be introduced during the rest of the year.

IEEE1394b informations >>

21.10.2004
Sony announces a new VGA IEEE1394b camera (XCD-V50)

AUSTIN, Texas – Oct. 19, 2004 – National Instruments today announced the industry’s first PCI Express-based image acquisition board for high-throughput vision applications. With the NI PCIe-1429 image acquisition board, engineers and scientists now can acquire images at the highest speeds, resolutions, and bit depths available for Camera Link cameras to perform demanding imaging applications such as synchronized data and image acquisition, fault analysis, and advanced motion tracking.

PCI Express technology

A higher performance, next generation of I/O interconnect technology -- PCI Express -- will serve as a standard local I/O bus for a wide variety of future computing platforms. This paper offers a technical overview of the evolution of PC buses, the physical and software layers of PCI Express, and the implications of this new technology on measurement and automation systems.

This paper looks at the success of the widely adopted PCI bus and describes a higher performance next generation of I/O interconnect technology – PCI Express – that will serve as a standard local I/O bus for a wide variety of future computing platforms. The paper also offers a technical overview of the evolution of PC buses, the physical and software layers of PCI Express, the benefits of PCI Express, and the implications this exciting new technology will have on measurement and automation systems.

More informations >>

19.10.2004
National Instruments today announced the industry’s first PCI Express-based image acquisition board

Variety of resolutions and speeds at market-leading price, and small form factor

Weybridge/Paris, 21st September, 2004 – Sony Europe’s Image Sensing Solutions Division today announced a range of digital cameras conforming to the CameraLink interface standard, including ultra-compact, lightweight VGA and XGA versions, and high-resolution variants for use in applications such as microscopy, medical imaging and education. The new devices combine the proven technologies that made Sony a pioneer in the field of machine vision, with the popular CamerLink interface. Featuring progressive scanning, frame rates from 15 to 60 frames per second (fps) and resolutions of up to 2Mpixel, the Sony XCL range of cameras allow systems integrators and OEMs to choose a Sony CameraLink-compatible camera for any application. The new devices are particularly suitable for users who wish to use the CameraLink interface to retain a traditional frame-grabber architecture to pre-process images.

All of Sony’s XCL models include a partial scan mode which increases effective frame rate by reading out only selected portions of the target image, enhancing performance in high-speed applications. In monochrome models, a binning function groups adjacent pixels of the sensor together vertically, to increase frame rate even further. Mathieu Forget, Product Marketing Manager Europe, from Sony Image Sensing Solutions, said, “The introduction of this strong lineup of cameras marks Sony’s entrance into the CameraLink market. It builds on the company’s longstanding pioneering approach in digital interfacing and continuing commitment to IEEE 1394, with strong loyalty to the machine vision marketplace. These CameraLink approved units are very strong, reliable, have among the smallest form factor and provide excellent picture quality, as one would expect from the Sony stable.”

The entry-level XCL-V500 and X700 are VGA and XGA versions respectively, giving systems designers access to a combination of features unrivalled in comparably-priced competing products. Unlike most CameraLink-compatible devices, they have an extremely small form factor of just 29 x 29 x 30mm and weight of only 55g, allowing them to be used in applications where space is at a premium. Both the V500 and X700 ultra compact models include a choice of internal and external sync, binning and partial scanning, and use a 1/3-type progressive scan (PS) interline transfer (IT) CCD.

For higher resolution applications such as microscopy, the XCL-U1000 monochrome and XCL-U1000C colour cameras use 1/1.8-type PS IT CCDs to offer 2Mpixel resolution at 15fps. The analogue PC monitor interface allows these devices to be used as part of “slimmed-down” display solutions without an external PC – for instance by connecting the camera directly to a PC monitor. Their high resolution and frame rate make them especially suited to mainstream machine vision applications such as automated inspection and process control, where the ability to catch fine details can significantly enhance the productivity of the overall system. Both models include partial scanning, while the U1000 also offers binning for further enhancement of effective frame rates.

All four devices will be available from November 2004.

Download datasheet>>

14.10.2004
Sony introduces full range of CameraLink-compatible video cameras

NI Vision Builder for Automated Inspection Version 2.5. You can use this configurable environment to build complete machine vision applications without programming. You can acquire and process images; communicate with industrial devices; and control the operation of lighting, triggers, and actuators. The latest version also features new algorithms, industrial connectivity, and enhanced flexibility.

For product tracking and identification, Vision Builder AI reads 2D codes such as DataMatrix and PDF-417. It particularly excels at reading direct part marking, where codes are often degraded, worn, or dirty. Vision Builder AI also includes two new algorithms for color inspection – color matching and color pattern matching. You can use both algorithms, common in packaging applications, for color inspection and verification.

In addition to acquiring and analyzing images, your inspection system often needs to interact with mechanical devices and actuators and communicate the inspection results. Vision Builder AI 2.5 improves these processes substantially by directly interfacing with many PLCs, PACs, and data acquisition products.

Vision Builder AI now acts as a Modbus slave to read and write values to a touch screen, PLC, or any other Modbus master. It also communicates with NI Compact FieldPoint to read analog measurements or change inspection setpoints dynamically. For PC-based digital I/O (DIO), Vision Builder AI controls any NI-DAQmx DIO line to route inspection results to actuators or receive signals from PLCs for product selection or status notification.

Vision Builder AI also simplifies the coordination of inspections from multiple cameras with a new image selection tool. With this feature and the new calculator step, you can make customized calculations and decisions based on the inspection results of images.

Learn more about NI Vision Builder AI.

04.10.2004
New NI Vision Builder AI Tools Inspect, Identify Parts

NEWS RELEASE – July 13, 2004– National Instruments today announced the industry’s highest-performance 3U PXI embedded controller. The NI PXI-8187 controller features a 2.5 GHz Intel Pentium 4-M processor and up to 1 GByte of double data rate SDRAM (DDR-SDRAM).

Engineers can use the new controller for a wide range of applications – from high-performance automated systems to low-cost embedded systems. The controller’s rugged and industrial packaging makes it ideal for performing a variety of functions in harsh environments, including machine monitoring and control, functional test and data acquisition.

The NI PXI-8187 controller incorporates an extensive set of peripherals such as hard drive, serial, USB, GPIB and Ethernet into a single module to ease system integration. National Instruments PXI embedded controllers operate with all PXI and CompactPCI peripheral modules and are available with Windows XP/2000 or NI LabVIEW Real-Time installed. NI delivers worldwide support for its controllers with installations of Windows in English, Japanese, Spanish, German, Korean, French and traditional Chinese.

About PXI
PCI eXtensions for Instrumentation (PXI) is an open specification governed by the PXI Systems Alliance (www.pxisa.org) that defines a rugged, CompactPCI-based platform for measurement and automation. PXI products are completely compatible with the CompactPCI industrial computer standard supported by 68 member companies and more than 1,000 products. PXI offers additional features, such as environmental specifications, standardized software and built-in timing and triggering.

13.07.2004
National Instruments Introduces Industry’s Fastest Embedded PXI Controller

The Swiss National TV came in the QUALIMATEST office

Play the movie >>

17.05.2004
QUALIMATEST on the TV

Sony digital IEEE 1394 cameras provide excellent colour quality at high resolution in any lighting conditionsImproved hardware and firmware advance DFW-SX910 and DFW-X710 cameras on popular previous models

Weybridge/Paris, 5 May, 2004 - Sony Europe’s Image Sensing Solutions division, one of the pioneers in IEEE 1394 technology, has announced successors to the company’s popular treated colour machine vision models. With immediate effect, the DFW-SX910 and DFW-X710 will replace the DFW-SX900 and DFW-X700 models. With their high resolution, range of features, and internal colour treatment, the DFW-X910 and the DFW-X710 cameras are ideal for quality-critical colour imaging applications, in any type of fluctuating lighting conditions.The two new advanced digital cameras incorporate an IEEE 1394 digital interface, are easy to install and use, and produce highly detailed, uncompressed images. The DFW-SX910 and DFW-X710 cameras are aimed at vision systems with low processor power or in need of white balance or picture adjustment. They are well matched to a variety of applications in industry such as surface analysis, factory automation and food processing or in the medical / pharmaceutical fields as microscopy. Both compact cameras employ a progressive scan CCD with square pixels and a new primary filter for exceptional colour reproduction. The DFW-SX910 is equipped with a 1/2-type 1,450,000-pixel CCD and offers SXGA resolution images up to 7.5 frames/s, while the DFW-X710 provides XGA resolution up to of 15 frames/s and is equipped with a 1/3-type 800,000-pixel CCD.As a result of Sony’s proprietary DSP development, both models incorporate a variety of convenient features such as an external and software trigger function, partial scan (16 x 16 zones), and have selectable output modes (frame rate/bit depth), making these cameras extremely flexible. The new integrated frame memory in the cameras guaranties a better and flexible use of the 1394 network bandwidth. The exposure output allows synchronisation with a strobe for improved capturing of fast moving objects. The DFW-SX910 and DFW-X710 units boast automatic and manual gain, and both models feature plug-and-play IEEE 1394 interfaces compliant to version 1.3 of the standard, providing up to 400 Mbps data rates. The DFW-SX910 and DFW-X710 cameras operate from an 8-30 Volts DC supply via the IEEE 1394 cable with a power consumption of 4 Watts. The cameras are housed in compact, rugged steel cases measuring 55 (W) x 55 (H) x 110 (D) mm (2 1/4 x 2 1/4 x 4 3/8 inches) and each weighs 250g.The cameras will be available from May 2004.

05.05.2004
SONY launches new Fire-Wire (IEEE-1394) digital color cameras

Compact Vision System and NI LabVIEW 7.1 Bring Reconfigurable I/O to Machine Vision

NEWS RELEASE – May 4, 2004 – Engineers now can execute more sophisticated image processing applications that require fast frame rates and complex algorithms with the latest version in the National Instruments rugged Compact Vision System series. The new NI CVS-1456 delivers 83 percent more processing power and eight times more memory than the original version of the Compact Vision System released in June 2003.

With the increased processing power of the NI CVS-1456, scientists and engineers now can speed inspections in the lab or on the factory floor by more rapidly executing advanced image processing algorithms such as pattern-matching and character recognition. Taking advantage of its 256 MB of nonvolatile onboard Flash memory, engineers and scientists can store larger images on the CVS-1456 system for future offline analysis.

Also, by combining the CVS-1456 system or previously released CVS-1455 system with the new NI LabVIEW 7.1 FPGA Module, engineers can completely reconfigure the 29 digital I/O lines of their Compact Vision Systems. With this capability, engineers can use the Compact Vision System for a wider variety of highly customized applications including packaging inspection, assembly verification and robot control.

“With the original Compact Vision System, engineers could run time-bounded algorithms using NI LabVIEW Real-Time on their vision inspection applications,” said John Hanks, NI director of measurements marketing. “Now, with the recent release of the LabVIEW 7.1 FPGA Module, engineers can customize the digital I/O on their Compact Vision Systems to perform tasks such as stepper motion control, custom system communication and intelligent part sorting. In the past, this level of flexibility would have required programming an FPGA with a hardware design language such as VHDL.”

Engineers also can use LabVIEW 7.1 to store large amounts of data and images on IEEE 1394 (FireWire) hard drives connected directly to their Compact Vision Systems for security and monitoring applications. They can store hundreds of gigabytes of images for offline quality control analysis or for logging all acquired images for days at a time.

Engineers can use the NI Compact Vision System to build applications with multiple cameras without the need for separate processing units, saving time and money. NI Compact Vision Systems feature three FireWire ports for connectivity to a variety of imaging sensors, and engineers have the flexibility to choose from more than 80 IEEE 1394 cameras. The systems easily integrate into rugged, industrial environments and are ideal for inspection, alignment, gauging and identification applications. NI Compact Vision Systems can withstand temperatures ranging from 0 to 55 degrees Celsius and shock and vibration up to 50 g. The product does not include fans, external vents or moving parts of any kind.

04.05.2004
The new Compact Vision Systems CVS-1456 is available

NEWS RELEASE -- Jan. 20, 2004 -- National Instruments today announced the new PXI-8252, an IEEE 1394 host adaptor that delivers PXI/CompactPCI connectivity to a wide range of industrial, machine vision cameras.

IEEE 1394 is an established industry standard for PCs and excels in machine vision applications in which large data transfers are common. With the PXI-8252 module, National Instruments further establishes itself as a leader in IEEE 1394 camera connectivity, with support for industrial IEEE 1394 cameras on PCI, PXI, CompactPCI and the new NI Compact Vision System.

The PXI-8252 module features three IEEE 1394 ports, delivers 12 W of power and supports data rates up to 400 Mb/s. The module, along with NI-IMAQ for IEEE 1394 driver software, creates an easy interface for image acquisition in various software environments including NI LabVIEW, Microsoft Visual Basic and C/C++. Engineers can use NI-IMAQ for IEEE 1394 to configure, control and acquire images from any IIDC-compliant IEEE 1394 camera. The PXI-8252 module is ideal for engineers wanting to integrate IEEE 1394 cameras into their rugged PXI systems.

With the PXI modular instrumentation platform, engineers and scientists can take advantage of cutting-edge PC technology and tools in their measurement and automation applications. PXI combines the high-speed PCI bus with integrated timing and triggering designed specifically for measurement and automation applications to deliver significant performance improvements over older architectures. PXI products maintain complete interoperability with CompactPCI, offering superior mechanical integrity, easy systems integration and more expansion slots than desktop computers.

20.01.2004
The new frame grabber Fire Wire (IEEE-1394) pour PXI is available

National Instruments CVS-1455 Delivers Three Times the Functionality of a Smart Camera

NEWS RELEASE -- Nov. 4, 2003 -- National Instruments today announced the NI CVS-1455 Compact Vision System, which delivers nearly twice the processing power and four times the storage of the NI CVS-1454 Compact Vision System released in July. With this optimized performance, engineers can use the new NI CVS-1455 to dramatically increase throughput of visual inspection applications.

"The NI CVS-1455 Compact Vision System high-performance processor, nonvolatile storage, and three IEEE 1394 (FireWire) ports make it well equipped to handle any inspection task, from precise assembly guidance to high-speed packaging inspection," said Tim Dehne, NI senior vice president of R&D. "In the past, engineers struggled to coordinate information and images from several independent machine vision nodes. Now they can integrate inspections into one embedded system without sacrificing performance. In fact, the NI CVS-1455 delivers the performance and functionality of multiple smart cameras."

Performing at 1,436 million instructions per second (MIPS), the NI CVS-1455 delivers more than three times the processing power of a typical smart camera. This speeds visual inspection while giving engineers the power to build applications with multiple cameras without the need for separate processing units, saving both time and money. Engineers can choose from more than 50 IEEE 1394-compliant cameras. The system also includes 128 MB of nonvolatile onboard Flash memory -- eight times the storage of a typical smart camera -- so engineers can store more images for offline quality control analysis. In addition, the NI CVS-1455 features 29 digital I/O lines for control and communication with PLCs, relays, Compact FieldPoint and other automation devices.

	NI CVS-1455	NI CVS-1454	Typical Smart Camera
Configurable Software	Vision Builder for Automated Inspection	Vision Builder for Automated Inspection	Available
Programmable Software	LabVIEW Real-Time	LabVIEW Real-Time	Not available
Typical Processor Performance	1436 MIPS*	883 MIPS*	60-360 MIPS*
Digital I/O	29 DIO	29 DIO	2-20 DIO
Cameras	up to 3	up to 3	1
Resolution	up to 2,000 x 2,000	up to 2,000 x 2,000	640x480
Frame Rate	up to 100 fps	up to 100 fps	30 fps
Nonvolatile Storage	128 MB	32MB	4-16 MB

*MIPS: million instructions per second

NI designed the rugged, 4 by 5 by 2.5 in. NI CVS-1455 to perform flawlessly whether aligning wafers in a clean room or inspecting spot welds on a factory floor. It can withstand temperatures ranging from 0 to 55 °C and does not include fans, external vents or moving parts of any kind, enabling it to easily integrate into harsh, industrial environments. The system’s high performance, flexibility and ruggedness make it ideal for inspection, alignment, gauging and identification applications.

Engineers can develop their machine vision applications on the NI CVS-1455 using either NI Vision Builder for Automated Inspection or the NI LabVIEW graphical development environment. Vision Builder offers an intuitive point-and-click interface for rapid application development. For more sophisticated, highly customized vision applications, LabVIEW delivers an open, full-featured development environment. The LabVIEW code generation feature in Vision Builder for Automated Inspection gives developers the power to easily migrate to LabVIEW.

04.11.2003
The new Compact Vision Systems CVS-1455 is available

As an addition sign to improve the quality standard QUALIMATEST took in September 2003 the certification of CSIA and passed it successfully. So, QUALIMATEST is one of the first european company, which fulfills the high requests to the registered members of the CSIA.Download our certificate >>

Aout CSIA :
In its second decade of serving as the beacon of good business practices for control and information system integrators and the companies that rely on them to translate the promise of technology into performance on the manufacturing plant floor, Control and Information System Integrators Association (CSIA) is the largest organization in North America for control and information system integrators.CSIA member firms provide manufacturers more than $1 billion annually in industrial automation systems, incorporating $400 million of hardware and software automation products. Its members, located in the United States and around the world, provide integrated control and information systems for clients in the automotive, chemical, food, healthcare, medical, metal, petrochemical, petroleum, pharmaceutical, plastics, power, printing, pulp/paper, rubber, utilities, and other industries.MANUFACTURERS: Find the right integrator for your industrial automation/control and information system projects – enabling selection by industry, application, location, and type of services required.
CONTROL AND INFORMATION SYSTEM INTEGRATORS: Learn about our association and what we offer to help you manage your business and improve profits and profitability

29.09.2003
QUALIMATEST is certified by CSIA

Select Integrator are distinguished members of the Alliance Program who have established a high level of business with National Instruments. Select integrators have broad product knowledge, extensive application experience, and a close relationship with National Instruments. At this date 17 Companies received this rating->Download the News from National Instruments Q3-2001 in german>>
->Download the News from National Instruments Q3-2001 in english>>
->Download the News from National Instruments Q3-2001 in italian>>->Download the official announcement at NIWeek 2001 in Austin>>

30.06.2001
QUALIMATEST is Select Integrator

Contact : info@qmt.ch

design by Seeaytch Advertising Network & ddellaro.ch