‘High definition’ radar for level measurement

14 November 2009

The introduction of the latest generation of ultra fast microprocessors to radar sensors has made a difference for level measurement. The faster MPUs bring more computing power to signal analysis, which allows more complex processing algorithms to be performed. This in turn makes the measurement simpler and more reliable.

'High Definition' radar level measurement
'High Definition' radar level measurement

The latest generation have much higher definition in signal processing and echo analysis. The instruments are now looking “five times closer” for much clearer echo detail, according to Doug Anderson, who was on hand at the Offshore Europe show in the UK.

The scale of this achievement can be compared to Hi Definition television, which gives a resolution about two times higher than conventional TV.

By using more detailed evaluation of the radar signals, the instrument gains better differentiation and tracking of the actual product level in vessel installations. This accommodates the market trend of implementing radar into ever smaller vessels, with shorter filling and emptying cycles.

The considerably faster signal processing allows the sensors to follow quick level changes. Instead of one image per second, the instrument operates at four images per second. Sensor accuracy has also been improved by over 30% for liquids and seven-fold for solids radar.

Nonetheless, all this extra performance consumes even less power than before. The new minimum operating voltage, at 9.6V on a standard two-wire device, offers wider compatibility with SCADA, DCS systems, ATEX, wireless, GPRS, battery and solar power installations, even with measuring ranges at 70m.

New style mechanics

On the mechanical side, improved antenna construction with glass sealing of the coupling system behind the antenna has improved integrity. An extension of the temperature range from –200° up to 450°C has been achieved with ceramic-graphite antenna options for both high and low frequency radar devices.

There are also higher chemical resistance metal antennas with new tantalum and titanium coated versions. The VEGAPULS 63 PTFE flush antenna will now operate from full vacuum to 16 bar and temperature ranges from –175° up to 200°C. The addition of the two-chamber stainless steel housing means this new generation radar offers an improved spectrum of options for optimised application compatibility in many areas.

Soon, a GPRS/GSM solution will be added, taking advantage of the new and much lower power consumption electronics and two-chamber plastic housing. It will have a simple ‘SIM card slot’ in a module inside the second chamber with no other external modem boxes or units required.

A special stand-alone housing version will be available to connect into existing plics transmitters. Units will be able to dial out to deliver data or warn of events; users can dial in to get a reading.

These GPRS/GSM SIM card devices will be able to be interrogated remotely for commissioning or maintenance using PACTware.

Additionally, a rechargeable battery powered pack for remote sites and inventory will also be an option to team up with this configuration, delivering a truly ‘stand alone’ device for remote sites.

The plics ‘platform’ is ideal for future product development of completely new ranges. VEGA radar technology will be introduced into new microwave barrier level switches VEGAMIP, to be introduced this autumn with ranges up to 100m and a wide range of antennas and multi configurations for non-contact level switching. www.vega.com

New microwave barrier switch

VEGA has also introduced another level product, primarily for bulk solids level measurement.

Called the microwave barrier VEGA‘MIP’ 61 (Microwave Impulse Point-level), it is a non-contact instrument which has no direct contact with the medium. For abrasive, aggressive or high temperature applications it can be installed  on the outside and measure through a microwave permeable window, e.g. in ceramic, glass or plastic material.

It can also be applied to liquid level detection or object detection, such as truck positioning and on conveyors and operates consistently with dirt, dust or build up. Ranges are up to 100m.

VEGAMIP T61 consists of a transmitter and one or several VEGAMIP R61 receivers for wider areas. The adjustable sensitivity receiver measures the attenuation of the microwave signal and outputs a relay switch. VEGAMIP can be used as a maximum or minimum sensor, switching delays can be set between 0.1 and 20 sec.

Fully integrated into VEGA's plics® modular system, there are a range of plastic, aluminium or stainless steel housings as well as different antenna systems and process fittings, thus allowing configuration of the sensor precisely to specific requirements.

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