Re: Detecting low power motion sensors
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A short "stub" of wire should work just fine for these frequencies.? After all, a 1/4-wavelength at 5 GHz is only 0.6-inches in free space.? In close proximity, even the open SMA should capture enough energy to show.??
Dave - W?LEV
On Sat, Oct 14, 2023 at 4:50?PM ANDREAS Decker < decker.a70@...> wrote: Greetings to all users of the TinySA community !
I have a TinySA Ultra with firmware updated to version 1.4-99 with which I can detect the transmission frequency of all devices at my disposal (remote controls, wifi routers, alarm sensors etc.)
The company that has deployed the alarm in a client's house under construction in 2011, has hidden several radio motion sensors inside the walls that were then plastered, simply by sliding the devices inside the brick cavities !
Some sensors activate the alarm at a distance of 1.5 meters, others even as close as 60 cm, so as to detect the passage of people accurately and only at certain strategic points such as hallways, stairs and other transit points, even outside the house.
The problem I¡¯m experiencing is that I cannot detect the transmissions frequency of these sensor. I¡¯m using the stock antenna with these settings: frequency span 100 MHz, Min Hold, RBW 300 KHz, LNA=ON. As I get closer to where the sensor is located, I expect to see a stationary signal which must decrease in intensity as I move away.
Since I don't know anything about the type of sensor and its transmission frequency, I focused my attention on frequencies typically used by these devices: 2.4 - 3 - 5.8 - 10.5 GHz, then also the entire spectrum supported by TinySA Ultra up to 20 GHz.
What is the best strategy to detect the signal ?
Which antenna should I use for the purpose ?
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