[Hackrf-dev] [hackrf-dev] Help and Support

Fri Jan 1 17:39:12 EST 2016

There are lots of 2.4G microwave systems out there using directional and omni directional  antennas.  These are units made by commercial vendors and Hams are using them to develop a private ham radio internet.  The precursor network is known as broadband hamnet and the latest incantation is AREDN.  It sounds like this might be what you are hearing.

Alan W6ARH

From: HackRF-dev [mailto:hackrf-dev-bounces at greatscottgadgets.com] On Behalf Of Chuck McManis
Sent: Friday, January 1, 2016 1:38 PM
To: Srinivasan T
Cc: Hackrf-dev
Subject: Re: [Hackrf-dev] Help and Support

Srini, you have remarked about this several times over the last year and while appreciate your enthusiasm I think this comment:

       > It seems , they don't understand about Radio and 2.4 GHz 

Might hit a bit closer to home.  It would suffice it to say that *YOU* don't understand about Radio and 2.4Ghz and that is why you don't see the obvious way to answer your own questions, and why we cannot answer them.

2.4Ghz is absorbed by water, because the water molecule forms a small dipole antenna of the correct length. That is why it is used in microwaves because it heats the water and that hot water heats the rest of the food. It is also why it is rarely used for long range communication, as the air has moisture in it which absorbs the signal, so not only are you fighting the inverse square law you're fighting atmospheric absorption. When it *is* used to send a signal more than a mile it is done so with a highly directional antenna pointing at another highly directional antenna on the receiving end. 

If you are seeing *any* sort of bump in the 2.4Ghz band, the source has to be less than a mile away and probably less than 1000 meters (or 1km). So what ever it is you're worried about, it is literally right next to you. Second 2.4Ghz is *HIGHLY* directional, it doesn't bounce much and bounces get double absorption so using any sort of directional antenna and a bit of geometry you could exactly pin point any *SOURCE* of 2.4 ghz power. And in my experience once you look at the thing sending out the RF energy you now exactly what it is trying to do.

So build one  using a potato chip can <http://www.makeuseof.com/tag/how-to-make-a-wifi-antenna-out-of-a-pringles-can-nb/>  (or buy <http://www.amazon.com/USB-Yagi-directional-Antenna-802-11n-2200mW/dp/B003LLS5JI> ) a directional WiFi antenna, hook it up, and rotate it around until your mystery signal peaks. Note your GPS coordinates and the angle with a good compass. Then drive 500 meters in any direction and do that again, then 500 meters in a *different* direction and do it a third time. (the protects against you accidentally picking a direction that is in line with the transmitter). Now take a map, and put your protractor on it, mark your tree measurement points and the angle. Draw lines out from the point. They will cross at the point where the transmitter is, go there. Look at the transmitter and what ever it is will be clear. If it is moving then that would be another good clue for you.

But here is the thing, you will never figure out what this is just by observing a signal, you have to go look at it.

--Chuck

On Fri, Jan 1, 2016 at 12:23 AM, Srinivasan T <tsvs.lc at gmail.com> wrote:

Hi There,

I detected unknown RF at 2.4 GHz which is not Wi-Fi.

This RF is not Wi-Fi, Bluetooth or Microwave, It has different FFT pattern, waterfall, and sound signature.

This signal also deliver Wi-Fi packets to make people believe it is Wi-Fi packets.

I use AirMagnet XT - 2.4 GHz  and the software also detected unknown interference.

Attached my analysis document.

https://mega.nz/#!YwplVCCT!Acbe00paHk3dLJuf04B5zSBifSw0-bHz5IciiNLgQwY

Please see following pages for quick understanding :

1. Page 18-19                     :  Conclusions

2. Page 43-46                     :  This page contains analysis of Radio Sound from 3 aspects : Sound Track, Sound Wave Form,

                                                 Sound WaterFall pattern. We can see that huge difference between Wi-Fi 2.4 GHz sound and unknown Radio Signal

3. Page 47-51                      : This external signal cause wifi fluctuations. Page 47 contains sample Wi-Fi signal from US which is really normal.

                                                  Page 50, using AirMagnet XT ( 2.4 GHx spectrum analyzer ) we can see that the external interference cause nearly 10 channels

                                                  affected. This is abnormal interference.

4. Page 52                            :  Relation of RF to human brain frequency

5. Page 61                            :  Video as reference, one of video :

                Unknown RF at 2.4 GHz reaction with human body with EEG 

                http://sendvid.com/dofuepqn 

                Details : This video shows the waterfall images. Each time we see set lines, the individual 

                will feel the reaction to body which not able to show to any other people. Please see EEG 

                window at right side at time 6.20 - 6.25 , 6.30-6.40, 6.50 - 6.55. The spike on EEG is 

                trigger by external factor and the individual can feel it.

                                                           ( other pages as supporting analysis )

I reported this issue to 3 RF spectrum managers :

1. iDA    - Singapore

2. MCMC - Malaysia

3. Balmon - Indonesia

It seems , they don't understand about Radio and 2.4 GHz 

If anyone could help with more data will be much appreciated or anything else. 

Regards

Srinivasan T

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