Архив за 20.12.2017

Comment on Decoding and Listening to HD Radio (NRSC-5) with an RTL-SDR by Anonymous

It didn’t work before but now it does. I was getting some kind of key regeneration error from Mediafire.

В Шарпе обновили плагин подавления шума. По сравнению со старой версией намного лучше работает. https://www.rtl-sdr.com/…

orlexy пишет:
В Шарпе обновили плагин подавления шума. По сравнению со старой версией намного лучше работает. https://www.rtl-sdr.com/sdr-noise-reduction-plugins-updated-sdr-console-testing-deep-learning-noise-redu...
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Широкополосный приёмник из DVB донгла - Страница #533

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Meteor M2 12/20/2017

submitted by /u/jeffreypkelly
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Comparison: Generic RTL-SDR R820T2 vs Nooelec Mini 2


Generic or branded? $8 or $21? Observations after Nooelec sent a brand-new Mini 2 (manufacturer, Amazon) for review (many thanks, disclaimer) and bought a fresh R820T2 off eBay. Identical receiver specs on paper, but are they really the same?



Interchangeable cases:



PCBs look quite similar, click on image for full screen view:



Upon closer inspection, component mounting on PCB, sideview:

Supplied mounts and coax cables: same diameter, same holding power of magnet, discover the difference between coax cables:



Supplied antennas: Mini 2 has more than twice the length and adjustable.



Why does it matter? Signals are received by the antenna, and with a larger / longer antenna you got a fleeting chance of listening to fun action bands below 200 MHz, e.g. airband with generic and silver telescopic, higher peak in the image better (able to understand voice):

Sidenote: receive performance matters primarily on antenna used, location, line of sight, and a host other factors, simply put, the Mini 2 with the supplied antenna will provide more listening pleasure.
Performance with external antenna: indistinguishable on an external discone by ear, tested on ADS-B and totals within three percent. Mini 2 has a less noisy waterfall image:


Try that again:


Don't ask why, only swapped dongles, both were fully warmed up.
Warranty: Mini 2 6 months, generics comes with 30 or 60-day warranty:


Support: close to nonexistent with a generic, Nooelec seems to be staffed with people who actually use what they sell, therefore can intelligently answer questions.
Reliability: Bought a Nooelec dongle more than four and a half years ago after generics failed, and that dongle is still ticking without any hiccups:



Featured in many old posts of yours truly (e.g. Reducing electrical noise) so it wasn't pampered, in fact, I bought my first Ham-It-Up after seeing that a dongle with Nooelec written on them won't let me down.

Conclusion


This or that? Truly believe that a generic RTL-SDR R820T2 is the best value for money in the radio world, and - be realistic - with bills looming on the horizon, $8 is less painful than $21. But with limitations: shoddy antenna, questionable build quality and no long-term support. Feel free to read up how to do a few mods for better performance if you understand the "DIY" moniker.
Which one would I buy? Reliability, warranty and performance are the keywords for me, so I'd go for the Mini 2, better still, spend that extra few bucks and get a Nooelec SMArt or rt-sdr.com v.3.

Comment on Displaying Live Weather and Traffic Data from HD Radio (NRSC-5) Signals by cr08

I’m very curious about this. How much of the above images are sent verbatim vs generated via the python script? Based on a brief view of the github it appears the weather map may just be sending the radar imagery and is overlayed via the script onto the map. The traffic map I’m more curious about though.

Airspy R2 vs professional scanners?

I've been using a RTL-SDR for a while now and I love it, but since there's no filter in my dongle, a lot of interference disturbs the signals - both from my USB and my antenna.

I've a SIRIO 68-78MHz dipole outside, so I should get good signals. Should I buy the Airspy R2 with SpyVerter R2 or a "real" scanner like Ericsson C602, C62 etc? How can I make my reception better and remove the interference?

Hope I explained it well, radon-n

submitted by /u/rado-n
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Antennas • Re: SDR Antenna Analyzer

Good point!

Per the product website, the noise source "generates a wide spectrum of white noise up to several hundred MHz." One could probably use the SDR to see at what frequency the source output gets too close to the noise floor of the system to give meaningful characterization of the antenna. Maybe this could be done by intentionally imbalancing the bridge with a >100Ω dummy load on the antenna connection. I don't see why leaving it open would not work. If there's a hard limit on the max frequency, it's probably where the toroid gets too leaky.

I'd have to think about how to do it, but the idea here is to basically get a frequency response function of the system using the random excitation of the source as the input and the reflected noise as the output. Normally I would think of it the opposite way; the output is what's leaving the antenna, not what's being bounced back. But by conservation of energy, anything that doesn't come back must have left through the antenna.

One of the parameters of a frequency response test like this is the coherence, which is a characterization of the linearity and time invariance of the system's response to the input. If the input is too low relative to the noise floor of the input or output, then the response will not cohere with the input. The frequency where the coherence starts rolling off would be where the source is not giving enough power to give meaningful analysis.

I will test this when I get the source kit up and running.

Thanks again for the excellent thoughts.

Statistics: Posted by apl — Wed Dec 20, 2017 2:49 pm


Comment on Video Tutorial: Installing GQRX and RTL-SDR on a Raspberry Pi by Anonymous

sudo apt-get

Комментарий к записи Приемник RTL-SDR.COM V3 — обзор новой версии (Александр)

Прозвонил входные цепи, замыканий нет, выпаивал защитные диоды, дроссель который на 5 вольтовый стабилизатор, ничего не изменилось.

Comment on A Video Tutorial about Receiving HRPT Weather Satellite Images by Tysonpower [Manuel]

Oh right…wow i really missed that? xD

Then it should be possible, but the RSP2 has some more filtering as it seems and is quite a bit more expensive. Curious if it also works with a Airspy Mini.

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