15 May 2018

How do you make sense of the frequency buzz?

Do you even know what frequency I am referring to? Exactly. Who really cares what the operating frequency of your level instrument is, or more specifically what the operating frequencies of your radar transmitters are? But, that seems to be the case today. One can hardly miss the clever marketing messages in print and electronic media focused on the operating frequencies of radar transmitters.

Does frequency matter?

Frequency does play a role from a design perspective. Lots of research and development went in developing a radar transmitter that operates over three times the operating frequency of mainstream radars transmitters, which is about 25 GHz. The release of the first radar transmitter operating at 78 GHz took place in 2011. It was truly a game changer in the solids level industry because of the vast irregularities of solids materials and extreme dust conditions that often presented serious limitations to main stream radars. But, a much higher operating frequency is not here to displace the lower ones. It is meant to address gaps or challenges in special circumstances typically associated with signal skipping (due to the properties of some solids materials) or the geometry of the silo or tank. With respect to liquid applications, very high frequency radar transmitters can be installed in less than ideal process connections, thereby reducing retrofitting costs. As a whole, thousands of tanks are fitted with instruments operating around 25 GHz in applications ranging from very simple to very tough. These environments can have lots of turbulence, vapors, agitators and other fixed obstructions. Yet now, for many, these conditions have been easily overcome with the intelligence and advanced algorithms vested on high performance radar transmitters.

Mostly though, frequency means nothing to the operator in general. All you need to know is if the correct level is being reported consistently and reliably regardless of the operating frequency. But these days, the operating frequency of radar transmitters is being talked about as the panacea to all level application challenges. All this talk does is make you second guess your radar level transmitters when, in most cases, you don’t need to. If your existing radar transmitter has worked well for years, what then is the compelling reason to change?

Are you considering changing transmitters because you can put in a taller standpipe or move it closer to the tank wall? Well, that is pretty much what you get with the “latest and greatest” radar transmitter at the nth frequency.

What if you are caught in a quagmire with too many frequencies to choose from?

Instead of focusing on frequency alone, evaluate your level application and what kind of information provides value to you. In some cases, radar transmitters are being offered as the “one technology fits all.” While this may be true in some cases, radar isn’t always the right choice in others. For more insight on this debate, check out my white paper on “Ultrasonic vs Radar. Letting the application drive the Technology .”

In order to choose the right technology, consider what has worked for you and if you experienced any issues. Then, re-evaluate your process to see if issues were caused by the technology, the installation or changes in the process. Tuning to another frequency may solve one problem while a new one shows up.

With radar transmitters, the higher the frequency, the narrower the beam angle of the transmitted signal. That is a good thing but is it always good? If an agitator blade or heating coil in the tank were to more directly interfere with the signal path, a narrow signal would most likely be blocked while the signal of an instrument operating at a lower frequency and with a wider beam would only partially be blocked and continue to reach the target (think laser to visualize this). If the marketing effort revolving around the operating frequency of radar transmitters is sending mix signals, consider your simple and challenging level applications and what instruments have delivered proven performance and desired results without you knowing the operating frequency.

What control and inventory management challenges have you thinking that it is time to try a different technology?

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