Wireless on/off control

[Ken9876]

Does anyone have any experience with 900 MHz frequency-hopping spread spectrum technology? This wireless system controls 16 points of I/O remotely. I only need to close one output. Is the 900 MHz signal the best to use considering the poor line of sight at my location? Or would a lower frequency system such as 27 MHz be better? I?m not up on the RF end of these systems so I have to trust the manufacturers both of which insist the others system is inappropriate.

 

[gndrod]

Does anyone have any experience with 900 MHz frequency-hopping spread spectrum technology? This wireless system controls 16 points of I/O remotely. I only need to close one output. Is the 900 MHz signal the best to use considering the poor line of sight at my location? Or would a lower frequency system such as 27 MHz be better? I?m not up on the RF end of these systems so I have to trust the manufacturers both of which insist the others system is inappropriate.

Not sure what type of equipment you are referring to but garage openers run 900mhz range with a dip switch for frequency selection. Could this apply?

 

[hurk27]

Does anyone have any experience with 900 MHz frequency-hopping spread spectrum technology? This wireless system controls 16 points of I/O remotely. I only need to close one output. Is the 900 MHz signal the best to use considering the poor line of sight at my location? Or would a lower frequency system such as 27 MHz be better? I’m not up on the RF end of these systems so I have to trust the manufacturers both of which insist the others system is inappropriate.

Knowing the right RF band to use will depend upon the dependability of the control you need, 900Mhz SCADA system is a good choice and 2.4Ghz can be even better both provide digital spread spectrum (frequency hopping) with PLL coding, below 100 MHZ is the start of ionosphere being able to cause interference from across the nation to around the globe and below 50Mhz it can be real bad in the time of high sun spot activity as we are approaching the 11 year cycle high, there are several bands for remote control, and each will depend upon what interference you might have in your area, a spectrum annalist could be done to determine this if you have a company in your area that does this kind of work, but most part 15 type transceivers that provide control are limited to only certain bands so even with a interference annalist done you could end up having to guess at which band would fit your need, if dependability is very important then digital transmission is a must as it is immune to most noises, I would say anything above 300Mhz and digital would be preferable.

Not sure what type of equipment you are referring to but garage openers run 900mhz range with a dip switch for frequency selection. Could this apply?

Many garage door openers operate in the 300-400Mhz range and the dip switches control the tone codes in the older units and the digital codes in the newer units and the newest units use what is called a rolling code that changes after each use to prevent recording of the code in use, same as newer car remotes and the same frequency band area.

 

[hurk27]

I will add that I have worked with multi-channel SCADA systems with transceivers over 4 miles apart on lift stations and never had a problem using a small unidirectional antenna and Yagi's can give even a higher range while blocking out side and behind emanating interferences.

 

[ActionDave]

I will add that I have worked with multi-channel SCADA systems with transceivers over 4 miles apart on lift stations and never had a problem using a small unidirectional antenna and Yagi's can give even a higher range while blocking out side and behind emanating interferences.

What is a Yagi? Right now we are doing this very thing on lift stations.
Well, I am not doing anything with the radios but would like to know more.

 

[Ken9876]

Wayne,

Thanks for the good info. I'm using a 900 MHz spread spectrum with frequency hopping. The old 900 system was become erratic. The Encom system I'm using has a spectrum analyzer function, so I did one of those tests and the area is very noisy at 900 MHz we?ll be using the Yagi antennas pointed to each location.

 

[steve66]

I think the 900 Mhz should be OK as long as you basically have a "line of sight" between the two antennas.

If you are farther away, I think the lower frequency might give you more range.

 

[steve66]

What is a Yagi? Right now we are doing this very thing on lift stations.
Well, I am not doing anything with the radios but would like to know more.

A yagi is a type of antenna that gives a gain compared to a straight vertical antennna. It is more directional than a basic vertical element. So the transmitter will focus the power toward the reciever, and to some extent, the reciever will block out noise from other directions.