Remote Control Receivers - Easily Drowned Out?

[kolbep]

Hi All.
I have a site with an ET Gate motor.
This motor has a built-in receiver onboard for the remote.
The problem is that the remote will only operate the gate up to 5m away.
I removed the onboard receiver completely, and went for an external receiver for another brand (Centurion Nova).
Same problem, the remote only works a couple of meters away.

Now, about 300m away from this site, there is a Sentech TV mast, that is used for all the TV, Radio, Cell and other signals in the area. We thought perhaps this trasmitter tower was somehow interfering, so the client got ICASA (Independant Communications Authority of South Africa) to come and assess for interference.

The ICASA technician went around the site with a Spectrum analyzer, and says he found nothing else on that frequency, and since the broadcaster has all things within their licences, etc, that his job is done.

Now, what I was wondering is, even though there is nothing on the 433mhz band interfering, could it be the high power transmittion in the other bands (both higher and lower frequencies), that could be overdriving the receiver, or swamping it out, making it less sensitive to receiving its own band? Perhaps all these remote receivers do not have a good enough bandpass filter (if any at all)....

Would be interested to hear your thoughts. If you want I can post photos of the receivers to see their front-ends?

P

[sunnyhighway]

The problem is that the remote will only operate the gate up to 5m away.

5m is just about 1 car length. Im inclined to say that's a good safety feature as there is a snowflake's chance in hell you could accidentally open the gate whilst the remote is in your pocket.

[cowana]

It depends on the front-end in the radio receiver. If it has a very wide bandwidth before the AGC (automatic gain control), very strong signals on seperate frequencies will cause it to reduce gain on the input, reducing the range significantly.

A solution would be to either use a radio module with a better quality front end, or to insert a bandpass filer between the antenna and the radio receiver.

[SeanB]

Going to cost you R1000, but buy a Super Nova, and mount the remote receiver nearer to where the car will stop to open the gate. Then mount the decoder by the ET motor and connect via a cable, Cat5 works well for this using 1 pair for power, one pair split for data and ground and the other 2 pairs for ground. Small, good security ( no decoded data available from the remote unit) and you can also have 2 other devices controlled from it as well.

Otherwise get an external antenna ( Centsys.co.za) and attach to the existing unit, it will help with the signal being swamped by the local high power transmitters. Mount the antenna 2m up inside some 50mm class 6 PVC drain pipe with an end cap on top, and the bottom mounted into a cement block by the gate. Paint green and put a SA flag on it to hide the fact. Lead the wire through some 20mm PVC conduit to the receiver which will be most likely close by. Put Blue Death inside to keep the goggas at bay, they love those receivers and the ET and Centsys motors, and destroy them. Geckos blow a lot of boards here as they stray across mains connections. Ants kill the encoders building a nest inside.

http://www.centsys.co.za/news-headlines/improving-your-remote-control-range

Info for you.

[Richard Crowley]

For US$5~10 you can get one of those USB dongle software-defined radios (SDR) and software to do your own spectrum analysis. And signal strength evaluation as well.
For example: http://www.ebay.com/itm/USB2-0-Digital-DVB-T-SDR-DAB-FM-HDTV-TV-Tuner-Receiver-Stick-HE-RTL2832U-R820T-/231284993997

It seems quite possible that all those broadcast and comms transmitters 300m away could be swamping the front-end of your receiver.
In addition to the other suggestions, a tuned-circuit for 433 MHz may help as a passband antenna filter, protecting the receiver from all those other strong signals.