By definition, telemetry reports events.

You should Google "scada". That's the systm that let's you control the processes, not just monitor them.

Yep. See Jennic Wireless Microcontrollers and Microwatt, among others.

I have seen the term "telemetry" used to refer to wireless signalling involving both monitoring and controlling functions.

In that usage, "Forward telemetry" refers to control; "Back telemetry" refers to monitoring.

Don't know if this is correct or typical usage in all types of engineering, but in medical device/ bioengineering that's what I've seen...???

Also "Housekeeping Telemetry" for transmitting battery voltage, current, temperature. I used this in Sounding Rockets and Cardiac Pacemakers. It is routine status information.

Most definitely yes. The factor to consider is time delays, both radio and scan times, a system can be tweaked to be fastish but if a repeater is being used then times are slower (2-10 secs). The indistry standard is to have a controller at the field end and just "radio" a remote setpoint to it, then the controller is doing its job at high speed and a change in remote setpoint taking 2-10 secs can possibly be tolerated. Some telemetry units have several PID controllers in its software (Kingfisher). If you are controlling a water basin which might take 2 days to go from empty to full, the telemetry delays will not be an issue. If you are controling a boiler drum level, it would be unadvisable.

Rok

Good point about delay. Interference potential is another factor to consider. Spread Spectrum is very popular in SCADA systems. Some systems use the same band for control and for data acquisition - if the same bandwidth is used on a "sequential use" model it would introduce delay: otherwise it creates the potential for interference. Where system security is paramount, the extra cost of licensed frequencies in the design is recommended - some providers feel the interference issues are significant in the unlicensed spread spectrum bands. http://www.atsionline.com/main2.htm A path study is also recommended to ensure the system design is robust. http://www.microwavedata.com/AboutUs/NewsandEvents/ResourceLibrary/ProperPlanning

Hi there, What are you monitoring? BR, Paul