M
mdf290
Of course its AM I thought you were asking about the radio stations in my car I mentioned... You need to make yourself clearer.
Yale Premium Alarm Hsa6400 Wirefree Alarm Kit
- Thread starter Chrispace69
- Start date
Of course its AM I thought you were asking about the radio stations in my car I mentioned... You need to make yourself clearer.
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Hello bernardgreen,
I am interested in discussing your theory of interference. I would like add a few points as I actually program (and design) microcontrollers, communication protocols with and without RF.
1. We know that Yale systems detect jamming, this is most likely done by calculating some threshold of noise on the frequency.
2. The threshold can be determined by averaging the noise (SNR) over a period of time, (this is how it is commonly done)
3. This threshold is low. In fact, it is low enough to have a few false positives. Being low also means that if the inteference is not in the threshold range, it will not cause a significant packet loss.
Let's think about this like UDP communication, the Yale sensors send tons of triggers or "UDP packets" to the "server". Some of these might fail, let's make an educated (pessimistic) guess and say that 1 in 4 packets will fail if there is some inteference but not enough to trigger the jamming detection.
When we design RF systems, we are aware of this, and as such send many many packets in one-way systems. Let's make a really pessmistic guess and say 1,000 triggers a second.
In this scenario, 750 triggers will still be registered in that second. Remember, it only takes 1 trigger packet to trigger the alarm. Assuming the house has 3-4 PIRs, and the burglars are in the house for 30 seconds, that would be about 90,000 triggers assuming 25% of them failed.
If you have any hard facts about these variables:
SNR threshold of jamming
Triggers per second for PIRs
Please let me know,
Thanks
I am interested in discussing your theory of interference. I would like add a few points as I actually program (and design) microcontrollers, communication protocols with and without RF.
1. We know that Yale systems detect jamming, this is most likely done by calculating some threshold of noise on the frequency.
2. The threshold can be determined by averaging the noise (SNR) over a period of time, (this is how it is commonly done)
3. This threshold is low. In fact, it is low enough to have a few false positives. Being low also means that if the inteference is not in the threshold range, it will not cause a significant packet loss.
Let's think about this like UDP communication, the Yale sensors send tons of triggers or "UDP packets" to the "server". Some of these might fail, let's make an educated (pessimistic) guess and say that 1 in 4 packets will fail if there is some inteference but not enough to trigger the jamming detection.
When we design RF systems, we are aware of this, and as such send many many packets in one-way systems. Let's make a really pessmistic guess and say 1,000 triggers a second.
In this scenario, 750 triggers will still be registered in that second. Remember, it only takes 1 trigger packet to trigger the alarm. Assuming the house has 3-4 PIRs, and the burglars are in the house for 30 seconds, that would be about 90,000 triggers assuming 25% of them failed.
If you have any hard facts about these variables:
SNR threshold of jamming
Triggers per second for PIRs
Please let me know,
Thanks
I have sent a private reply.
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