Can i capture a Stand-By Cell Phone in Sweep Mode?

#1 · 28/05/2021, 14:33

Quote from AdminTC on 28/05/2021, 14:33
Yes since even a non moving cell phone which has a stable net connection will connect from time to time to its linked cell phone tower and the SPECTRAN V6 is fast enough to capture most of those short bursts even within sweep mode (offering a >1THz/s sweep speed).

The following real live experiment simply monitors a stand by cell phone laying on the table using a SPECTRAN V6 with the follwing mission:

The Time Shift block is used and set to a 2GByte buffer to allow around 14 seconds of data capturing with a 1024FFT resolution (45MHz bandwidth). This gives you enough time to see the signal and to stop the capturing in time. After some minutes of silence we captured the following transmission with a length of about 10 seconds:

To have a look at the signal and package structure we can now select any part of the signal within the Time Shift block and get a perfect data zoom within the attached Waterfall block:

We can see quite long transmissions (the above example shows a 8ms package) but also some very short transmissions. Lets focus on the short transmissions and select one of those:

We can see that we have a lot of empty space between some very short data packages. Lets zoom furter in to analyze the packages. They consist of two packages which are frequency shifted:

If we digg in a bit more we can analyze a single package:

The package length seems to be around 500µs. Using a lower FFT of 16 offers us a super high time domain resolution to verify this finding:

And indeed we get a quite accurate 500µs pulse length. Looks even more interesting using the 3D view:

So lets make some math: If we use our fastest 1THz/s sweep mode we have a POI around 5ms for the full 6GHz range which would be to slow to 100% capture a single 500µs package but since we see that hundreds of those packages are transmitted for every "hallo world" data transfer and most packages are within "much" longer time shifted blocks of 10ms or even longer it is quite likely that we will see all cell phones in stand by even with a slower sweep mode of 250GHz/s (default).

Yes since even a non moving cell phone which has a stable net connection will connect from time to time to its linked cell phone tower and the SPECTRAN V6 is fast enough to capture most of those short bursts even within sweep mode (offering a >1THz/s sweep speed).

The following real live experiment simply monitors a stand by cell phone laying on the table using a SPECTRAN V6 with the follwing mission:

Cell Phone Monitoring an IQ capture mission

The Time Shift block is used and set to a 2GByte buffer to allow around 14 seconds of data capturing with a 1024FFT resolution (45MHz bandwidth). This gives you enough time to see the signal and to stop the capturing in time. After some minutes of silence we captured the following transmission with a length of about 10 seconds:

Cell Phone Stand By Signal Capture

To have a look at the signal and package structure we can now select any part of the signal within the Time Shift block and get a perfect data zoom within the attached Waterfall block:

Cell Phone Data Transmission

We can see quite long transmissions (the above example shows a 8ms package) but also some very short transmissions. Lets focus on the short transmissions and select one of those:

Zoom to Cell Phone Data Range #1

We can see that we have a lot of empty space between some very short data packages. Lets zoom furter in to analyze the packages. They consist of two packages which are frequency shifted:

Zoom to Cell Phone Data Range #2

If we digg in a bit more we can analyze a single package:

Zoom to Cell Phone Data Range #3

The package length seems to be around 500µs. Using a lower FFT of 16 offers us a super high time domain resolution to verify this finding:

Cell Phone Data Range Burst with super high FFT resolution

And indeed we get a quite accurate 500µs pulse length. Looks even more interesting using the 3D view:

3D Cell Phone Burst Spectrum View

So lets make some math: If we use our fastest 1THz/s sweep mode we have a POI around 5ms for the full 6GHz range which would be to slow to 100% capture a single 500µs package but since we see that hundreds of those packages are transmitted for every "hallo world" data transfer and most packages are within "much" longer time shifted blocks of 10ms or even longer it is quite likely that we will see all cell phones in stand by even with a slower sweep mode of 250GHz/s (default).