Controlled Communications: A
Frequency Detector-Jammer
What
is it?
The
frequency detector-jammer as discussed on this website is a
device that (ideally) will detect WiFi, Bluetooth, and
cellular signal transmissions within a radius of 10m. Then
(and only then), it will jam any frequency bands that have
been detected. This allows the device to avoid having to
constantly send out a noise signal, which results in
significant power savings whenever no one is attempting to
communicate nearby. Lower power consumption means longer
and more feasible battery usage, which, in turn, leads to
cost savings and greater portability.
What is its purpose and why did we choose to make it?
The
two primary purposes of the detector-jammer described above
are to avoid disturbances and to enhance security.
“Disturbances” can refer to any distractions,
interruptions, or intrusions commonly caused by wireless
communication devices in everyday settings (e.g., cell
phones ringing during a movie, lecture, or church service,
or students surfing the web during class). Enhancement of
security would primarily be relevant to government agency
briefings, corporation board meetings, and the like. For
such circumstances, it may be crucial that certain inside
information remain on the inside without any leaks (e.g.,
enforcement of “no cell phone” rules where secret or
proprietary documents could be leaked to outside parties
via cell phone MMS).
We chose to
make a device that could fulfill these purposes in a more
power-efficient manner because we estimated a significant
market for such a device. Due to FCC restrictions, jamming
licensed band communications (i.e. cellular bands), is
illegal for the common citizen and therefore the device
would have to be sold either to the government or outside
the United States where jamming restrictions are
either much more lax or simply nonexistent.
How
does it work?
As originally
envisioned, the device would wait for any signal to be
detected, then, based on which frequency band was detected,
the device would turn on the corresponding subjammer for
that particular band. However, due to time and equipment
constraints, we decided to design and construct a
“proof-of-concept” device. This proof-of-concept device
only considers communications in the 2.45 GHz band. It
simply waits for a WiFi or Bluetooth signal to be detected,
then turns on the single jammer via the processor
interface.
See the Design section for
detailed design information. This includes
Detector,
Interface, and
Jammer information,
as well as Modifications
required to
build a real-world device from our proof-of-concept
design.