What is vna

This data can therefore be stored in places separate from where primary data is being acquired and stored. If certain medical images are not in regular use, it is mandatory for the hospital to archive them for a period of five years. PACS servers allow large volumes of medical imaging data to be stored that has infrequent use and to be retrieved when needed. PACS servers can also back-up medical images and archive them separately, so that a digital copy exists in the event of system failure.

When a particular image is needed for analysis at a later date, the clinician can search for it in the PACS server using any one of these tags and retrieve the file easily. Traditionally, a PACS server comes coupled to the radiology workstation, which thus provides both the machines used to acquire images and the DICOM-viewing software in the same location. While PACS is an efficient storage system for large volumes of imaging data, it does present a problem when it comes to sharing and enhancing medical images.

PACS is usually restricted to a single system confined to a single department. Edits made by one department may not be visible to others. This makes inter-departmental collaboration difficult. Another problem with PACS is the difficulty of migrating to another vendor. The image is acquired from the source and directly stored in the PACS. The method of storage can vary between vendors. VNA, as the name suggests, dissociates itself from all vendors of medical imaging equipment.

The simplest vendor neutral archive definition is that it is an application that stores medical images in a standard format with a standard interface. Therefore, images stored in VNA can be accessed through any workstation, irrespective of the vendor.

VNA overcomes the problems of PACS by allowing medical images to be stored and viewed in an integrated manner from multiple devices and locations. The method of adding tags varies between vendors, and so the final medical image file may not be compatible with other applications. VNA allows healthcare providers to migrate from one vendor to another without worrying about imaging data loss. While PACS is focused on improving the workflow with emphasis on storage and retrieval, VNA is mostly focused on providing back-up and archiving that will survive the long haul, even if the vendor changes.

Since VNA has only been around for a few years, it is still an expensive investment, which is its biggest drawback. Most VNAs available today integrate with storage that is available on the healthcare premises. This can increase the monthly storage costs. Cloud storage refers to the process of using the internet to store files. In order to understand more fully how a vector network analyzer operates, it is useful to see a basic block diagram of the test instrument.

The diagram shows the very basic blocks of the VNA including the signal ports, the signal separation blocks, the receiver detector, and finally the processor and display.

The block diagram of a basic two port vector network analyser is shown above. This shows the high level blocks needed for a typical VNA. The VNA has precision connectors on the front panel of the unit itself and then precision cables are used to connect these to the device under test. Precision cables are required because the phase and loss of a standard cable would vary too much with even slight movement, etc. To test the device, a variable frequency signal is generated within the vector network analyzer and the output is switched to test the DUT in either one direction or the other.

In this case the left hand side on the diagram is selected. The signal passes to the splitter where one output is used as the reference signal for the receiver and the other side is passed to a direction coupler and then into the DUT via the external connection on the VNA and the precision cables.

Power passes through the directional coupler directional coupler 1 to the DUT, but the third port detects the reflected power and this is connected to the receiver again. Power that passes through the device under test is sampled by directional coupler 2 and this signal is connected to the receiver. Apart from generating a signal to power the device under test, the signal source also has an output that is connected to the receiver.

This enables phase information to be gained from the detected signals. Currently vector network analyzers will make significant use of digital signal processing, and there much of the receiver and detector section will be undertaken in digital format. The signals are processed by the receiver are then fed to the processor and display. This section will again make heavy use of microprocessor technology to provide the control, functionality and user friendly displays that are needed for modern test instrumentation.

Although this very simplified example of an RF network analyzer shows two ports, some vector network analyzers may use more ports for systems where many different signal paths exist.

RF network analyzers can be very expensive items of test equipment. However they are invaluable in the design of RF networks - particularly filters and any other items where the RF performance of the item needs to be accurately assessed.

In this way it is possible to fully understand what is happening and ensure that the overall design operates correctly. Typical high end vector network analyzer, VNA in use Types of RF network analyzer Within the broad scope of RF network analyzers, there are various types of instrument which can be bought and used.

These types of RF network analyzer are very different, but they are all able to measure the parameters of RF components and devices but in different ways: Scalar network analyzer SNA : The scalar network analyzer, SNA is a form of RF network analyzer that only measures the amplitude properties of the device under test - i.

In view of this it is the simpler of the various types of analyser. Not only does the it measure the amplitude response, but it also looks at the phase as well. Forgot your password? First Name. Last Name. Job Title. I'm interested in newsletter subscriptions.

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