[Hackrf-dev] Decode the Signal

Wed Oct 14 11:01:32 EDT 2015

Wi-Fi will send sudden power to cause huge fluctuations - here's a picture
of it doing that: http://i.imgur.com/txXyOXB.jpg
Since you're sampling at 2MHz, the Wi-Fi channel is much wider than your
view, so you see the whole noise floor rise.

On 14 October 2015 at 15:14, Srinivasan T <tsvs.lc at gmail.com> wrote:

> Hi There,
>
>
>
> Thanks.
>
>
>
> *The details that I can gather from RF that interfere :*
>
>
>
> 1. The Wi-Fi router will not send sudden power to cause huge fluctuations.
> It is always constant power. The graph will look like sine linear waves.
>
> 2. Every Radio signal has a sound. The signal that interfere at 2.4 GHz is
> not Wi-Fi sound. ( Totally different sound )
>
> 3. The density value for 2.4 GHz really high unless you near to the source
> at 10 cm distance
>
> 4. Waterfall Images for Radio Signal at 2.4 GHz is really not matched with
> available waterfall image for 2.4 GHz. ( I compare with metageek waterfall
> images )
>
> 5. AirMagnet XT is really can identify thousands of patters of
> interference at 2.4 GHz but this time Air Magnet XT detected as new FFT
> pattern.
>
> 6. There is always RF which has power around -20 dBm to -40 dBm (
> Everywhere - Singapore ,Malaysia and Indonesia )
>
> 7. Modulated at low frequency ( 30-100 Hz ) and it deliver small
> electricity
>
>
>
> I have captured the signal using kismet manual to save the file to .iq but
> I dont know on how to go further.
>
>
>
> Regards
>
>
>
> Srinivasan T
>
>
>
> *From:* Dave New [mailto:den at densbe.com]
> *Sent:* Wednesday, 14 October 2015 10:10 PM
> *To:* Srinivasan T; 'Mike Walters'
> *Cc:* 'hackrf-dev'
> *Subject:* RE: [Hackrf-dev] Decode the Signal
>
>
>
> Some (all?) WiFi access points "poll", that is, if they currently have no
> active connections, they go through a sleep/wake cycle where you will see
> the signal appear and disappear in cycles.
>
>
>
> I saw this on the Comcast/Xfinity Technicolor router that they started
> shipping to their customers earlier this year in certain US markets.  Their
> router has three different signals running, one of which has no SSID.  The
> other two are your locally-defined wireless network, and the much-maligned
> "xfinity wireless" which Comcast claims is to provide "free" WiFi to the
> world (or at least to your neighbors).  It's really not free in the respect
> that you have to be a Comcast customer with a valid login to use it, and it
> obviously is using someone else's (not Comcast's to be sure) electricity to
> host the signal (and your bandwidth).  But I digress.
>
>
>
> The 3rd signal turns out to belong to Comcast/Xfinity's wireless home
> security system, and is there whether or not you've paid for that option.
> If you use a simple app like WiFi Analyzer on an Android phone, you can see
> this signal come and go in a few second cycle, essentially polling for its
> home security devices.  Since there were none at my place (that belonged to
> Comcast) it instead managed to effectively interfere with my local wireless
> network.  Apparently a number of wireless clients are befuddled with having
> a strong signal come and go on the channel they are trying to use.  The
> result was a number of devices kept complaining about getting disconnected,
> or downloads and other streaming would halt and start, and other annoying
> things.
>
>
>
> It also turned out that I couldn't move either of the other two signals
> off of my chosen channel for my local network.  Whenever I changed the
> channel for my local network, the other two signals would follow it (?!),
> thus guaranteeing that anything running on the other signals would slow
> down access to my local network.  What's particularly maddening about this
> is that Technicolor's implementation of what have should have been a simple
> VLAN exercise is flawed.  It should have worked, but apparently they can't
> program their way out of a paper bag.  At my workplace, we use access
> points that are running up to 16 VLANS (hosting such things as a guest
> network, employee network, visiting employee network, supplier network,
> etc, etc), and they perform flawlessly.
>
>
>
> I put up with this for about a week, and took the router back to the local
> Comcast office and told them I didn't want it.  I went out and bought an
> Arris/Motorola Surfboard 6121 cable router which does not have wireless in
> it, and a Cisco wireless firewall/router.  Everything now runs fine, and
> I'm no longer fighting with two other signals I didn't want and did not
> intend to use.
>
>
>
> 73,
>
>
>
> -- Dave, N8SBE
>
>
>
> -------- Original Message --------
> Subject: Re: [Hackrf-dev] Decode the Signal
> From: "Srinivasan T" <tsvs.lc at gmail.com>
> Date: Wed, October 14, 2015 9:11 am
> To: "'Mike Walters'" <mike at flomp.net>
> Cc: 'hackrf-dev' <hackrf-dev at greatscottgadgets.com>
>
> Thanks.
>
> I can see that there is one signal interfere at 2.4 GHz.
>
>
>
> Do you want me to capture .iq file using 20 M ?
>
>
>
> *From:* Mike Walters [*mailto:mike at flomp.net* <mike at flomp.net>]
> *Sent:* Wednesday, 14 October 2015 7:14 PM
> *To:* Srinivasan T
> *Cc:* hackrf-dev
> *Subject:* Re: [Hackrf-dev] Decode the Signal
>
>
>
> The signal in the first and second videos is Wi-Fi - if you use a sample
> rate of 20M you can see it much clearer.
>
>
>
> On 14 October 2015 at 07:28, Srinivasan T <*tsvs.lc at gmail.com*
> <tsvs.lc at gmail.com>> wrote:
>
>
>
> Dear All,
>
>
>
> I am managed to do some RND with unknown Signal at 2.4 GHz. This Signal
> works almost everywhere in Singapore, Indonesia and Malaysia.
>
> Here some video for reference :
>
>
>
> *Here is the video :*
>
>
>
> Ø  *FFT at 2.4 GHz ( we can see sudden fluctuation and power in db is
> really high - in Singapore at home ) *
>
> *      https://sendvid.com/33f5hpkg <https://sendvid.com/33f5hpkg>*
>
> *        Detail : On this video, we can see peak hold in green color that
> leave a trace something comes and go*
>
>
>
> Ø  *Spectrum Density of RF at 2.4 GHz ( in Medan - Indonesia )*
>
> *        http://sendvid.com/mu9m2jeg <http://sendvid.com/mu9m2jeg>*
>
> *        Details : I have taken this video at place where there was no
> devices that operate at 2.4 GHz ( near plantations ). We can see noise
> floor in blue color comes and go.*
>
> *                         This external interference cause Wi-Fi at 2.4
> GHz to fluctuate and sudden fluctuate at different power level will
> increase of SNR of Wi-Fi ( signal to noise ratio )*
>
>
>
> Ø  *AirMagnet XT ( in Singapore at home )*
>
> *      Attached video file, file name ;   https://sendvid.com/tkq3xz0s
> <https://sendvid.com/tkq3xz0s>*
>
> *      Details :    This software one of the best software available in
> the market for detection interference Wi-Fi at 2.4 GHz with different
> options. We can see FFT picture at real *
>
> *                        time in leave suddenly max hold around -10 dBm. (
> We can spectrogram picture as well ).  There are 2 rules to be remembered :*
>
> ·         *If power level increase suddenly to 10 dBm then the source
> should be near and visible to me but on this case we dont see the source*
>
> ·         *Any RF Transmitter at 2.4 GHz will transmit at constant power
> and sudden increase of power at middle of transmission really no possible.*
>
>
>
>       *Wi-Fi Fluctuations at Siloam Hospital in Medan - Indonesia*
>
> *http://sendvid.com/2u2j34m7* <http://sendvid.com/2u2j34m7>
>
>
>
> I would like to request on how decode header information or others of the
> signal. I have captured .iq and .cfile using HackRF :
>
> *https://www.dropbox.com/s/wj77dm4n7fj7rcl/Signal%20Capture.7z?dl=0*
> <https://www.dropbox.com/s/wj77dm4n7fj7rcl/Signal%20Capture.7z?dl=0>
>
>
>
>
>
> Please advise on  decode the signal.
>
>
>
> Regards
>
>
>
>
>
> Srinivasan T
>
>
>
>
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