Intermittent Interference with LTEM Alarm Communicator

Thread Starter

Rick15752

Joined Jan 14, 2024
4
I install electronic security systems that typically use cellular communicators to send and receive data. These communicators can be iP/cellular or cellular only. One site in particular, using a cellular only communicator, showed a consistently strong signal but intermittently bad signal to noise ratio. This is a residential installation. I installed an external antenna, meaning external to the communicator's plastic housing not external to the home. It's a 4dB gain antenna according to the manufacturer. This seemed to help, but the signal to noise, quality of signal (QOS) was still intermittent, two bars and never better than -15dB. Signal strength remains good around -85dBm.

The homeowner added a few plug in WiFi extenders over the years to obtain better WiFi coverage, these were unplugged to see if the interference was coming from those. Slightly better but not by much, QOS still a problem.

I noticed the home has roof top solar panels, so now I'm wondering if the RF interference is from the solar system. I've read that solar inverters improperly installed / shielded can create an RF problem over a wide signal range. I don't think it's physical obstruction created by the solar panels attenuating the cell signal from the tower, the signal in the home is strong, just noisy.

The cellular communicator works, sends and receives data, but on a rare occasion goes into a communication failure. The homeowner understands this and is okay with leaving it as it is.

I can replace the communicator with a ip/cellular type, thereby using WiFi for the primary data pathway with cellular as a backup, which would considerably reduce the chances of a communication failure.

So, I'm suspecting the solar inverter to be what is generating RF interference. I would like to make sure if that is the cause

I'm looking for some advice on pinpointing the source of RF interference.
 

nsaspook

Joined Aug 27, 2009
13,261
I install electronic security systems that typically use cellular communicators to send and receive data. These communicators can be iP/cellular or cellular only. One site in particular, using a cellular only communicator, showed a consistently strong signal but intermittently bad signal to noise ratio. This is a residential installation. I installed an external antenna, meaning external to the communicator's plastic housing not external to the home. It's a 4dB gain antenna according to the manufacturer. This seemed to help, but the signal to noise, quality of signal (QOS) was still intermittent, two bars and never better than -15dB. Signal strength remains good around -85dBm.

The homeowner added a few plug in WiFi extenders over the years to obtain better WiFi coverage, these were unplugged to see if the interference was coming from those. Slightly better but not by much, QOS still a problem.

I noticed the home has roof top solar panels, so now I'm wondering if the RF interference is from the solar system. I've read that solar inverters improperly installed / shielded can create an RF problem over a wide signal range. I don't think it's physical obstruction created by the solar panels attenuating the cell signal from the tower, the signal in the home is strong, just noisy.

The cellular communicator works, sends and receives data, but on a rare occasion goes into a communication failure. The homeowner understands this and is okay with leaving it as it is.

I can replace the communicator with a ip/cellular type, thereby using WiFi for the primary data pathway with cellular as a backup, which would considerably reduce the chances of a communication failure.

So, I'm suspecting the solar inverter to be what is generating RF interference. I would like to make sure if that is the cause

I'm looking for some advice on pinpointing the source of RF interference.
If you think it's solar related is there a day/night correlation with the communications errors/failures and signal quality quality issues?
 

Thread Starter

Rick15752

Joined Jan 14, 2024
4
If you think it's solar related is there a day/night correlation with the communications errors/failures and signal quality quality issues?
There doesn't seem to be a uniform pattern that would correlate with day/night, overcast/clear weather, etc.
 

Thread Starter

Rick15752

Joined Jan 14, 2024
4
The cellular communicator checks into the server once a day. I can ping the communicator for its' QOS but there is no way I can determine minute by minute over a course of a week, month, year QOS ratings. I've pinged the communicator throughout various times of the day and get adequate readings, but then an occasional bad QOS.
 

nsaspook

Joined Aug 27, 2009
13,261
There doesn't seem to be a uniform pattern that would correlate with day/night, overcast/clear weather, etc.
Solar equipment interference should only happen when the sun is up if it's a normal grid-tie system. Replacing the communicator with an ip/cellular type seems prudent.
 
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