Garage Door Transmitter sensing experiment

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Andy

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Sep 9, 2022, 4:19:13 AMSep 9
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Greetings,

I have been trying to detect the transmission from a couple of different garage door opener transmitters, and I wonder if anyone has experienced this.   My 6G Combo+ will detect a lot of different transmitters I have tried including even key fobs.  But an odd thing happens when I try to detect a garage door opener in the 300 MHz band;   Nothing at all.   tried many different settings, RBW, etc.   I can detect other 300MHz transmitters that have broader bandwidth, but two different types of garage door opener brands detect no power at all. (yes they work).

Do you think it is possible that the bandwidth on a door opener is so narrow that the rf-explorer cannot detect it?

RF Explorer

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Sep 9, 2022, 3:01:43 PMSep 9
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Hi Andy,

It may be this specific transmitter create very short duration pulses, and therefore depending on your setup may not work.
Please configure your RF Explorer in this way:

* Use left-side connector 50Khz-960MHz module as it is faster than right-side module
* Center Freq: 300MHz
* Freq Span: 5MHz
* Calculator: MaxHold

Regards,
RF Explorer Team

Andy

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Sep 10, 2022, 1:08:59 AMSep 10
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Thank you for the reply.   Yes, I tried that and it just doesnt show anything.  I have tried old and newer garage door openers, and none of them show on the Explorer.   Maybe you are right and garage door opener signals are too short to register.

Mr Fame

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Sep 10, 2022, 4:57:59 AMSep 10
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I would double check that you are in the right frequency range. I have been able to catch even super short bursts just by using a larger rbw, a small frequency window, and centering on the frequency of interest.

Cross reference the fcc id of the device online. This will verify the operation frequency.

Good luck!
-Jason 

Sent from my iPhone

On Sep 9, 2022, at 10:09 PM, Andy <dire...@oknasa.org> wrote:

Thank you for the reply.   Yes, I tried that and it just doesnt show anything.  I have tried old and newer garage door openers, and none of them show on the Explorer.   Maybe you are right and garage door opener signals are too short to register.
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Rod Heazlewood

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Sep 12, 2022, 12:32:10 PM (12 days ago) Sep 12
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Hi Andy,
Use a Scanner to find the frequency and listen to the audio for rapid data
pulses.  The timing of the data could indicate if this is very short bursts, or
slower wide-bandwidth pulses.
Set your RF Finder to the centre frequency with 2mHz sweep setting.
This gives 1mHz either side of your frequency to identify the data pulses 
when transmitting to the garage door unit.
Cheers,
Rod Heazlewood. Christchurch, NZ.
~~~~~~~~~~~~~~~~~~~~~~~~~~

On Sat, 10 Sep 2022 at 5:09 PM, Andy <dire...@oknasa.org> wrote:
Thank you for the reply.   Yes, I tried that and it just doesnt show anything.  I have tried old and newer garage door openers, and none of them show on the Explorer.   Maybe you are right and garage door opener signals are too short to register.


On Friday, September 9, 2022 at 2:01:43 PM UTC-5 RF Explorer wrote:
Hi Andy,

It may be this specific transmitter create very short duration pulses, and therefore depending on your setup may not work.
Please configure your RF Explorer in this way:

* Use left-sidconnector 50Khz-960MHz module as it is faster than right-side modul
* Center Freq: 300MHz
* Freq Span: 5MHz
* Calculator: MaxHold

Regards,
RF Explorer Team

On Friday, September 9, 2022 at 10:19:13 AM UTC+2 Andy wrote:
Greetings,

I have been trying to detect the transmission from a couple of different garage door opener transmitters, and I wonder if anyone has experienced this.   My 6G Combo+ will detect a lot of different transmitters I have tried including even key fobs.  But an odd thing happens when I try to detect a garage door opener in the 300 MHz band;   Nothing at all.   tried many different settings, RBW, etc.   I can detect other 300MHz transmitters that have broader bandwidth, but two different types of garage door opener brands detect no power at all. (yes they work).

Do you think it is possible that the bandwidth on a door opener is so narrow that the rf-explorer cannot detect it?

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You received this message because you are subscribed to the Google Groups "RF Explorer" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rf-explorer...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/rf-explorer/8a1e3576-2543-4219-be55-5d4cbe7ff51bn%40googlegroups.com.
--
Rod Heazlewood
South Island Electronics
Mobile: 021 884 478
Toll Free: 0800 021 478

Andy

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Sep 15, 2022, 2:44:52 AM (10 days ago) Sep 15
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Thank you for all the replies which were all very helpful.  I checked some other opener transmitters using the advice here, and I was able to see the signal on the RF-Explorer.   It turns out that the problem I had with the original transmitter was actually a problem with the transmitter!  When I was testing it on the explorer, I wasn't actually able to test it on the gate that it opened.   But when I did, found out it had stopped working.   So I used the explorer to make repairs, and trim the antenna to optimal length.

Thanks again.

Simon Hockenhull

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Sep 16, 2022, 4:20:19 AM (8 days ago) Sep 16
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Glad you have found the problem. I have had similar experiences with ca key fobs, security alarms etc and found that using a hand held radio scanner centred around the frequency band of 417-419 MHz or around the 433 MHz band has helped trace the problem. Once you know the frequency the device uses you can then bring your RF explorer into play to actually see the pulses and check for amplitude and also any interference that may be blocking the signals.

Cheers

Simon.

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