Low Cost PCB's Low Cost Components

Author Topic: 2ghz pulsed transmission?  (Read 825 times)

0 Members and 1 Guest are viewing this topic.

Offline CopperCone

  • Frequent Contributor
  • **
  • Posts: 344
  • Country: us
2ghz pulsed transmission?
« on: August 16, 2017, 03:56:20 AM »
I have a bicone hooked up to my SA and I found a weird pulsed signal on almost exactly 2GHz. It appears to be a very slow amplitude(on off) modulation, almost like a beacon. Like it turns on every 2 seconds for a second and turns off. Very slow. Literary like human seconds.

Any idea what this might be? I looked at it for a while and it appeared to be repetitive.  :o
« Last Edit: August 16, 2017, 03:58:36 AM by CopperCone »
 

Offline Karlo_Moharic

  • Contributor
  • Posts: 37
  • Country: hr
Re: 2ghz pulsed transmission?
« Reply #1 on: August 16, 2017, 04:36:13 AM »
Check you router or wireless modem , sometimes they can have certain features enabled. For example on my router there is a WiFi feature that in a way works like a beacon for WiFi reciever.
 

Offline Yansi

  • Super Contributor
  • ***
  • Posts: 1243
  • Country: 00
  • STM32, STM8, AVR, 8051
Re: 2ghz pulsed transmission?
« Reply #2 on: August 16, 2017, 04:44:03 AM »
Wifi is not 2Ghz, so... what?
 

Offline CopperCone

  • Frequent Contributor
  • **
  • Posts: 344
  • Country: us
Re: 2ghz pulsed transmission?
« Reply #3 on: August 16, 2017, 04:58:09 AM »
yes, it does not appear to be a frequency related to cell phones or wifi. appears to be fairly powerful too.

I will try to find it again. I saw it last month and its been bugging me since.

ok, thats different. it appears to be a bunch of spikes when I center around 2 GHz with 50MHz bandwidth. Kind of looks like some kind of digital communications.

Before there was just a pulse that went on and off. Maybe I remembered the frequency wrong...

What is the purpose of beacons anyway? I figure anything computer related would be alot faster then a few Hz frequency.
« Last Edit: August 16, 2017, 05:09:43 AM by CopperCone »
 

Offline StillTrying

  • Frequent Contributor
  • **
  • Posts: 972
  • Country: gb
  • 100% Brand New and High Quality, in theory.
Re: 2ghz pulsed transmission?
« Reply #4 on: August 16, 2017, 05:32:06 AM »

Online T3sl4co1l

  • Super Contributor
  • ***
  • Posts: 9174
  • Country: us
  • Expert, Analog Electronics, PCB Layout, EMC
    • Seven Transistor Labs
Re: 2ghz pulsed transmission?
« Reply #5 on: August 16, 2017, 06:12:06 AM »
There's GSM bands at 1850.2 – 1909.8 and 1930.2 – 1989.8 (MHz, uplink and downlink respectively).

I've seen GSM-850 around here, that looks like a picket fence of carriers with digital (flat topped) bands appearing within them from time to time.

Hmm, I didn't try demodulating it, I should.  It ought to be that freaking bit-bit-beep-bit-bip GSM sound that bleeds into freaking everything...

Tim
Seven Transistor Labs, LLC
Electronic Design, from Concept to Layout.
Need engineering assistance? Drop me a message!
 

Online metrologist

  • Frequent Contributor
  • **
  • Posts: 853
  • Country: us
Re: 2ghz pulsed transmission?
« Reply #6 on: August 16, 2017, 06:24:00 AM »
This is what I get off my specially tuned 2GHz paperclip.
 

Offline w2aew

  • Super Contributor
  • ***
  • Posts: 1643
  • Country: us
  • I usTa cuDnt speL enjinere, noW I aR wuN
    • My YouTube Channel
Re: 2ghz pulsed transmission?
« Reply #7 on: August 16, 2017, 06:36:02 AM »
Most likely cellular downlink (tower to handset).
======================================
YouTube channel: http://www.youtube.com/w2aew
FAE for Tektronix
 

Online TheSteve

  • Supporter
  • ****
  • Posts: 2125
  • Country: ca
  • GHz or bust
Re: 2ghz pulsed transmission?
« Reply #8 on: August 16, 2017, 06:59:19 AM »
I doubt it ever turns off. Check out band 2 LTE - 1930-1990 MHz, as w2aew mentioned this is the cellular base station to handset link.
If it is LTE you can expect carriers 5/10/15 or 20 MHz wide.
VE7FM
 

Offline CopperCone

  • Frequent Contributor
  • **
  • Posts: 344
  • Country: us
Re: 2ghz pulsed transmission?
« Reply #9 on: August 16, 2017, 07:47:45 AM »
This is what I get off my specially tuned 2GHz paperclip.

Yes, I see something similar on those frequency ranges, but with more resolution (maybe its my RBW?)

This signal I speak of was just a spike that appeared and disappeared. I believe I even put my instrument into receiver mode (0 Hz span) to check for modulation. It just appeared and disappeared with a very low frequency in the seconds.

When I look at the cell/wifi bands, I see spikes that dance around (probably because its only 10mS maximum update rate). I assume each is a data channel that someone is using. 2 modulated carriers per connection right, so its duplex. Digital stuff looks like... well its doing something fast.

 This thing was slower then someone keying morse code.
« Last Edit: August 16, 2017, 07:50:04 AM by CopperCone »
 

Online metrologist

  • Frequent Contributor
  • **
  • Posts: 853
  • Country: us
Re: 2ghz pulsed transmission?
« Reply #10 on: August 16, 2017, 10:21:47 AM »
50 MHz span and 30kHz RBW, IIRC. Not sure about VBW.
 

Online Lord of nothing

  • Frequent Contributor
  • **
  • Posts: 360
  • Country: at
Re: 2ghz pulsed transmission?
« Reply #11 on: August 24, 2017, 09:10:04 PM »
What I know in the US the use ~2ghz for Sat Radio and Sat Phones.  :-//
There are more thinks like Zigbee for example.
Made in Japan, destroyed in Sulz im Wienerwald.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf