4 ms·

What's fascinating is that it can run in 'stealth' mode while still remaining compliant inside the 2.4ghz frequency band.

walrus01 8y ago
It may not show up in a scan of 802.11(abgn/ac) compliant devices, but something like this can be located with equipment as cheap as the spectrum analysis features built into an old 802.11n rocket m2 radio ($60-70) and antenna ($30). https://www.google.com/search?q=rocket+m2+airview&num=100&client=ubuntu&hs=a8T&channel=fs&source=lnms&tbm=vid&sa=X&ved=0ahUKEwillOOupOLfAhXrslQKHSPqAKkQ_AUIESgE&biw=1432&bih=1024 https://www.google.com/search?q=rocket+m2+airview&num=100&cl...
- trishmapow2 8y ago
  Or alternatively a HackRF clone ($100 from Alibaba etc), ADALM-PLUTO etc if you want an SDR that can cover a few GHz instead - these are great fun, even a $10 RTL-SDR is amazing (tops out at 1.5GHz though).
  - jsjohnst 8y ago
    My Aruba Wi-Fi network will readily detect it too (have APs dedicated to air monitoring and spectrumRF both)
akira2501 8y ago
> it can run in 'stealth' mode In a low-noise environment, sure; this technique surely blows the SNR through the floor. Plus, being an OFDM signal you're probably going to lose all reception while the device is in motion.
- logicallee 8y ago
  >In a low-noise environment, sure; this technique surely blows the SNR through the floor Could you elaborate about why this would affect SNR? Do you just mean because the band is narrower, or is there a new source of noise? (Or something else.)
  - cbhl 8y ago
    I believe the poster means you could look at signal strength to find the "hidden" network
    - logicallee 8y ago
      Thanks. What does "blows through the floor" mean?
      - jwandborg 8y ago
        In that context they probably mean that the signal will be much harder to interpret for a receiver.
myself248 8y ago
There are a bazillion other narrower-than-wifi schemes that work in the same band. All the pre-wifi stuff, Symbol Spectrum24 and Xircom Netwave and Proxim HomeRF, for instance. Ricochet poletops used a 1Mbps rate just like Bluetooth, and hopped it over the same chunk of spectrum. Heck, Bluetooth itself is a great example. Won't see that on a wifi stumbler, but it's certainly compliant.
retSava 8y ago
Regarding being compliant - there are more factors coming into play than just middle freq and transmission power. You also need to have the width of the transmission under control, occupied bandwidth. Harmonics in adjacent bands must be suppressed. The transmitter duty cycle cannot be too high. The channel must be free before you transmit, etc etc.

walrus01 8y ago

It may not show up in a scan of 802.11(abgn/ac) compliant devices, but something like this can be located with equipment as cheap as the spectrum analysis features built into an old 802.11n rocket m2 radio ($60-70) and antenna ($30). https://www.google.com/search?q=rocket+m2+airview&num=100&client=ubuntu&hs=a8T&channel=fs&source=lnms&tbm=vid&sa=X&ved=0ahUKEwillOOupOLfAhXrslQKHSPqAKkQ_AUIESgE&biw=1432&bih=1024 https://www.google.com/search?q=rocket+m2+airview&num=100&cl...

trishmapow2 8y ago
Or alternatively a HackRF clone ($100 from Alibaba etc), ADALM-PLUTO etc if you want an SDR that can cover a few GHz instead - these are great fun, even a $10 RTL-SDR is amazing (tops out at 1.5GHz though).
- jsjohnst 8y ago
  My Aruba Wi-Fi network will readily detect it too (have APs dedicated to air monitoring and spectrumRF both)

akira2501 8y ago

> it can run in 'stealth' mode In a low-noise environment, sure; this technique surely blows the SNR through the floor. Plus, being an OFDM signal you're probably going to lose all reception while the device is in motion.

logicallee 8y ago
>In a low-noise environment, sure; this technique surely blows the SNR through the floor Could you elaborate about why this would affect SNR? Do you just mean because the band is narrower, or is there a new source of noise? (Or something else.)
- cbhl 8y ago
  I believe the poster means you could look at signal strength to find the "hidden" network
  - logicallee 8y ago
    Thanks. What does "blows through the floor" mean?
    - jwandborg 8y ago
      In that context they probably mean that the signal will be much harder to interpret for a receiver.

myself248 8y ago

There are a bazillion other narrower-than-wifi schemes that work in the same band. All the pre-wifi stuff, Symbol Spectrum24 and Xircom Netwave and Proxim HomeRF, for instance. Ricochet poletops used a 1Mbps rate just like Bluetooth, and hopped it over the same chunk of spectrum. Heck, Bluetooth itself is a great example. Won't see that on a wifi stumbler, but it's certainly compliant.

retSava 8y ago

Regarding being compliant - there are more factors coming into play than just middle freq and transmission power. You also need to have the width of the transmission under control, occupied bandwidth. Harmonics in adjacent bands must be suppressed. The transmitter duty cycle cannot be too high. The channel must be free before you transmit, etc etc.