Archive for July, 2012

The Doppler Effect

Wednesday, July 18th, 2012

So you thought “The Doppler Effect “was only a throwaway term used in The Big bang TV series

 The Big Bang

High frequency occupancy sensors uses ultrahigh-frequency radio waves, also known as “microwaves” and the principle of the Doppler Effect to detect motion. 

The sensor sends out radio waves that bounce off of nearby surfaces and return to the sensor. Motion in the area changes the speed of the waves returning to the sensor. The sensor detects the change and interprets it as occupancy. This causes the sensor to turn ON the load.

Multi detection methods meet different applications

Wednesday, July 18th, 2012

Passive Infrared (PIR):

Senses occupancy by detecting the difference between the heat emitted from the human body in motion and the background space. Best for use in areas with (1) an unobstructed view, (2) high air flow, and (3) ceiling mounts.

Ultrasonic:

Detects motion by bouncing ultrasonic waves off of objects and analyzing the frequency shift between the emitted and reflected sound waves. Best for use in areas with (1) low air flow, (2) partitions and dividers, and (3) high levels of minor activity (e.g., an office space).

Microwave:

Detects motion by bouncing ultra-high frequency electromagnetic waves off of objects and calculating the frequency shift between the emitted and reflected waves. Best for use behind a fixture lens because it can detect motion through dense non-metallic materials.

Dual Tech:

Uses both passive infrared and ultrasonic detection methods in order to maximize reliability and minimize “FALSE ON”. Best overall performance for most applications.

 

Monitor-IT/Find-It/Fix-It: Isolating and Correcting Underperforming devices & controllers

Wednesday, July 18th, 2012

Monitoring & tuning can be difficult. Any control system that is not tuned for maximum performance can be costly.

By using intelligent led solutions you can monitor the system performance by accessing real-time and/or historical process data for analysis and tuning.

The use and supports the automation functions alarming, scheduling, and trending (AST™). This includes a local scheduling service as well as the possibility to configure several local and remote 24 hour schedulers through the Web interface.

Alarming includes functionality to generate, deliver, acknowledge, and display alarm conditions, regardless of whether alarms occur in the device or arouse the control network. The trending capability includes a periodical or event-driven logging of values with time stamps. Logged events and trend data are stored by the controllere and can be exported with CSV files from the device via an FTP connection.

Controllers that include event-driven e-mail notification as a result of a predefined action triggered by a specific status or an exceeded high limit.

E-mail notification can also be set-up as well be used to forwarded event and trend data as e-mail attachments (CSV files) for long term storage to a central SQL database.

Lighting and HVAC in one controller = One system integrator!

Wednesday, July 18th, 2012

The convergence of IP and building automation networks is undeniable and enables the integration of diverse applications and systems. Just to name a few, IP can connect energy metering & management, building automation, video surveillance, access control, and even fire & alarm systems. Managing several, or all of the above, from a single interface can offer unprecedented levels of reactivity and cohesion between systems.  It can also reduce overlapping software, labour and training costs. This is why IP enabled controllers and building management systems will win.

For system integrators, to manage HVAC and lighting simultaneously with a single controller means reduced hardware, installation and logistics costs. For end-users, it means better return on investments and shorter payback periods.

So, if someone is proposing to use a specialist BMS control contractor and a lighting control system integrator contractor on the same project – STOP and ask why?

The same specialist system integrator could undertake both roles!

FTP Response Codes

Tuesday, July 17th, 2012

Following are links to the detailed articles for the FTP response codes.

FTP Software – Using XCRC to Verify Data Integrity

Tuesday, July 17th, 2012

So FTP software support XCRC error checking, a feature that has been added to many FTP Servers, such as Serv-U. The XCRC command uses a CRC (cyclic redundancy check) to verify the data was transferred correctly. The algorithm used is CRC-32, a very well known standard algorithm that ensures the data sent is the same as the data received.When FTP softwware is connected to a server that supports XCRC, it automatically checks the XCRC value with the server to ensure the content of the data is correct. If the XCRC check fails, FTP  automatically retries the file transfer.

Latency versus Bandwidth – What is it?

Tuesday, July 17th, 2012