How do I correct all those spikes?

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Javiyo
Posts: 1
Joined: Wed Dec 28, 2016 1:39 am

How do I correct all those spikes?

Post by Javiyo » Wed Dec 28, 2016 2:00 am

Hi, I´ve been in SDR for a month or so with the RTL-SDR V3 dongle and I've noticed that there are a lot of spikes, not everywhere but in a lot of places.
I simply ignored them because they weren't in the frequencies that I was interested, but now I´m trying to decode NOAA and they are really annoying. I think they have something to do with the usb but I don´t know any way to get rid of them, any suggestions?
http://imgur.com/gallery/4jcpS
Some images there, thank you!

AD5NL
Posts: 34
Joined: Fri Sep 16, 2016 7:00 pm

Re: How do I correct all those spikes?

Post by AD5NL » Wed Dec 28, 2016 3:23 am

*Some* of those might be from the dongle itself.

But I have been able to reduce quite a few spikes just by being very rigorous about the following:

* Grounding. Ground your PC chassis if you can. Try to ground the dongle if you can.

* Ferrite chokes. Get a whole bunch (like maybe 50 or 60) of 5 mm snap-on ferrite chokes. You can buy 20 of them on Amazon for maybe $12. Put a couple on your USB cable (I really recommend using a USB extension cable to separate your dongle from your PC). Then go around the house and start putting ferrites on power cables (especially laptop power cables and "wall-warts"). Also put them on ethernet cables. You will be amazed how much stray RF you can kill just by properly adding chokes.

* Turn stuff off around the house! Turn off every computer monitor and television and radio you don't need. Some LED lightbulbs also generate a lot of stray RF.

* I found that I got a lot of RF coming from WiFi routers, cable modem, and network switch. Try to move as far away from these as possible!

I noticed that when I did all of these things that the amount of interference on VHF airband (118-138 MHz) went down considerably.

AD5NL
Posts: 34
Joined: Fri Sep 16, 2016 7:00 pm

Re: How do I correct all those spikes?

Post by AD5NL » Wed Dec 28, 2016 8:20 pm

Looking at your photo, it looks like you might have ferrites on your USB cable. (Good job, that is step #1).

Generally you will also want to put one on your antenna coax as well, to prevent common mode interference. My standard procedure is to put one near the terminating connector and one near the feed point.

Also, are you using the stock antenna? If so, is it indoors? An outdoor antenna will generally help to reduce interference from devices. And certainly an outdoor turnstile or QFH will pick up a lot more of the pass than the stock monopole.

rtlsdrblog
Site Admin
Posts: 2432
Joined: Mon Nov 19, 2012 11:54 pm

Re: How do I correct all those spikes?

Post by rtlsdrblog » Wed Dec 28, 2016 10:40 pm

This is probably noise from a nearby electronic device. Try turning off equipment in your room/house and see if it goes away. It could also be from your monitor or the USB cable.

Also, what is your antenna, and where is it? Ensure there are no noisy electronic devices near the antenna too, and get it up high outside of the house.

on1bes
Posts: 28
Joined: Sat Dec 24, 2016 11:03 pm

Re: How do I correct all those spikes?

Post by on1bes » Sat Dec 31, 2016 6:58 pm

There are always spikes (static lines), if you use a indoor antenna, or the antenna is to close to the PC / Laptop. The distortion in house is so big, that you can not receive weak signals from the outside. Even NOAA is mostley not possible with indoor antenna. Grounding is not always a solution, if you not known how to do it. At least, place you antenna so high as possible (outside) or on a window (if you in high building).

Username
Posts: 508
Joined: Sun Oct 09, 2016 7:27 am

Re: How do I correct all those spikes?

Post by Username » Fri Jan 20, 2017 10:19 pm

It comes from your Pc/ Monitor. Here the same Problems a lot of noise. Even an Outdoor Antenne dont help becouse the dongle pic the noise up. :roll:

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