Архив за 17.06.2019

Приемник RTL2832 + R820T изначально позиционируется как приемник для стандарта dvb-T. Стандарт dvb-T предусматривает шир…

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Приемник RTL2832 + R820T изначально позиционируется как приемник для стандарта dvb-T. Стандарт dvb-T предусматривает ширину полосы пропускания = 8 МГц, должна быть и соответствующая частота дискретиза...
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Широкополосный приёмник из DVB донгла - Страница #568

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Comment on Tutorial: Replay Attacks with an RTL-SDR, Raspberry Pi and RPiTX by søren

piam command also not found for me. rpitx seems to be able to transmit a WAV file anyway, but it doesnt appear to unlock my car. I know it could be because of rolling codes, but it is a very old car so i doubt it

KerberosSDR • Re: Update rate not showing

So I'm definitely leveraging enough power for the sdr - I highly doubt that's the issue here.

Statistics: Posted by stasia327 — Mon Jun 17, 2019 1:18 pm


Comment on An RTL-SDR Based Ground Penetrating Radar & Metal Detector by Celalettin Uçar

A deep learning for gpr but ofcourse it is not real. Rtl sdr sampling rate capability is not enough to create a real gpr. Its only 2.8 mbps 🙂 a real gpr least sampling rate requirement is approximately more than 300 times. so i call it as a gpr simulation… on the other hand, if you use an enhanced sdr, it is possible with same method. Thank you

Comment on An RTL-SDR Based Ground Penetrating Radar & Metal Detector by Belayet H.

Understood the fact over your comment-conversations. Now it is more clear about principle of operation and capabilities are more like a Metal Detector. Thanks so much for everything.

My best V-Dipole so far!

Hey guys,

After lots and lots of trial and error regarding reception of NOAA-signals with a V-dipole, I really was about to create a DCA or QFH. That was until I got in contact with an amateur astronomer who published some of his captures of NOAA-sats with a quality I only could've dreamt about, done with a V-dipole as well.

So, I want to disclose some information so it should become easier for every beginner to start capturing NOAA-signals.

- In the basis one just needs to build the all-famous V-dipole by Adam. I've used a 1.25m long plastic pipe sold for waste water with a diameter of 32mm as a mast.

- Connect the elements with coax using a simple choc-bloc. I've inserted the coax on the same side of the choc-bloc as the elements. So, I'm only occupying one side of the bloc. Just to attempt lowering the resistance, since I suck at soldering.

- Create an air choke balun of 6 windings.

- 27.25cm below the elements, you'll create 3 reflectors of 2 elements each. That means, 3 choc blocs and each reflector has it's elements installed at about 60 degrees.

- The size of the elements for the reflector are 54.5cm. So, 1.1cm longer than the elements connected to your coax.

The result of the antenna should be something like this: https://i.imgur.com/la76QKV.jpg (my reflectors got moved a little mounting it on the roof, I have to adjust it but the captures are stunning already).

I've mounted it on top of my house, so that's at an altitude of about 10 meters and it's survived hurricane-like wind speeds.

I had an enormous gain boost, causing less noise and bigger surface of the capture.

After that I put back my BPF and LNA and I've managed to receive captures from Spitsbergen to Tunesia (depending on the pass, not all in 1 capture).

Image result with BPF + LNA: https://i.imgur.com/bXCvzs5.png (pity something went wrong in the transmission of the signal, or at least the capturing of it for 10 seconds or it would've been near perfect. The audio got completely silent.)

Good luck people!

.... for those curious what the vertical little antenna is for: it's to receive signals on 433mhz and turned out to work superb as well for ADS-B. Receiving airplanes at a distance of up to 350km.

submitted by /u/theakito
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(META) We need to talk about self promotion.

A few users keep on spamming every thread with links to their websites with vague and often outright untrue information.

This is almost every post they make. Its annoying.

It's really frustrating to see someone being rude and jabbing a link in random posts without actually helping. The links are so random that they dont address the issue. In a few he lies about what will happen and links to the website anyways.

Can we consider ensuring a user is giving a certain level of helpful advice if they want to spam their website?

/u/on1bes

submitted by /u/sillyinvesterinpx
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Power Supply Interference

Power Supply Interference

I'd recently hit some issues with receiving NOAA images and had made the mistake of making multiple changes all at once (I was too eager to do more and more), so I had a hard time figuring out what I'd done wrong to go from reasonably good images to poor images.

I then tried to go through everything, trying to work out what was the root cause of images like the one shown on the left when I was able to get ones like the one shown on the right which shows some winter weather about to hit New Zealand in a day or so.

https://i.redd.it/31p2vqkp0v431.jpg

Just about every option seemed to make no real significant change until for about the 15th time I took the QFH down from it's mast and was using it to get good images when it was on a table and connected directly to my laptop so I could see the QFH / downlink cable / FM block / SDR / USB cable combination really did work to produce images and there was nothing obvious when viewing the waterfall output from SDR# when it was connected to my laptop.

Nothing seemed to make sense until I tried what I thought wouldn't impact it when I swapped out the power adaptor that came with the Raspberry Pi and instead used the charger for my mobile phone. The results are as shown. Clearly the original power supply is putting out a huge amount of interference which is swamping the signal I'm picking up.

So if nothing makes sense, try changing your power supply!

submitted by /u/KiwiEntropy
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Comment on SignalsEverywhere Podcast: Satcom Piracy Interview by Greg

No thanks. I’m not going to listen to an idiot who doesn’t even know that “underground” is one word.

wxtoimg To Determine Which Sensor Used?

I am continuing development of my scripts and adding features to them, but I've come into a bit of an issue. I found that on some passes, certain sensors weren't activated on the NOAA sats, so certain enhancements could not be applied. For this reason, I'm curious to know if there's a way to determine through wxtoimg or other means, which sensors were active for the pass, so I know which enhancements to apply.

I've poked about in the man pages for wxtoimg, but none of the verbose options really produce just that output. One option is to process the signal to make an image and capture the printout, as that has the channel a/b sensor number displayed, but I'd rather be able to do it more simply. Beyond that, is there a comprehensive table of which images require which sensors? Any help is appreciated!

submitted by /u/tgyk
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