Optical meter reading


 MI 3 2005 CA Optical Meter Reading

When entering a low budget market such as the AMR  market for residential ustomers, alternatives must be present to allow transition phases  from on-AMR to smart meters. If OMR overcomes a set of stringent operating rules, it is a valid solution and it can serve as an alternative.The requirements are:

• Easy-to-install, nondestructive placement
• Lifespan around 10 years
• One model fits all philosophy
• Must produce reliable data

Xemex decided to take up the challenge in late 1998, and started with a low-power consuming  CMOS platform. This technology provided a camera chip and some onboard intelligence for image decoding. A pre-production model was assembled and is still active in the Demo Corner on our website. This first model could be fitted on most gas and electricity meters and had  an IR light source to ensure good decoding circumstances under all conditions.

The lifetime  issue was also a major concern to the design team. To be able to deploy OMR for gas and  water meters, Xemex decided to go wireless. To get the most out of the local power supply, the company developed a proprietary RF communication protocol.

Putting the two solutions  together provided the current OMR solution – the WatchTalk Optical module IMR-1010. The  module collects data by evaluating the image of the digit before the comma. If this image changes the module tries to identify a number. If it succeeds, it needs to decode this  same number again after 20 seconds. This interval can be reprogrammed remotely for higher or lower reading frequencies,depending on the application needs; otherwise it is optimised  for optimal battery life. Two consecutive character readings confirming the same digit are the basic condition for a valid read-out.

The module permanently collects data and keeps track of consumption at 15 minute intervals. Over 24 hours, the module creates 96 sub-totals and offers enough information to create consumption profiles of a quality comparable to any professional, industrial AMR system.