Архив за 22.07.2018

Complete noob considering buying a second SDR

I'm sorry if this is a complete noob question, but I don't know what I don't know. I bought one of the $10 rtl_sdr's from aliexpress and got it on Friday. It's already proven itself to be ridiculously helpful for a few of my arduino projects. The only issue is that I find myself switching it around from machine to machine. I'm not a radio geek. I don't know what I'm doing yet, but as I'm looking for a second one, I'm seeing a chunk of them in the $40 range with names such as

Best RTL SDR receiver USB SDR dongle with Realtek RTL2832u SDR and Rafael micro R820t2

and

New RTL SDR RTL2832U R820T2 HF TXCO SMA in SDR#, HDSDR, GQRX or SDR Touch

They are boxes instead of dongles and have bigger antennas. Is this going to get me anything that blue plastic one doesn't? It's 4x the price.

Secondly, are there any particular aftermarket antenna people like with these plastic units?

submitted by /u/mudmin
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Кто подскажет как сканировать частоты на моторолла GM660…

Кто подскажет как сканировать частоты на моторолла GM660

User Projects • Re: TETRA Trunk Tracker for use with SDR# and TETRA Demodulator plug-in

I'm not sure how I fixed it (probably a reboot or hide encrypted data option) but I don't hear the encrypted voice on low volume anymore. :)

Something else I noticed: TTT is setting the WFM bandwidth to 26 kHz, while I see people around the internet mentioning or advising 25 kHz, 40 kHz, 48 kHz, etc. Either of those setting work for me but sometimes when the frequency drifts a little bit decoding weak signals becomes more difficult. What about making it a little bit wider or customizable?

Statistics: Posted by Remon — Sun Jul 22, 2018 10:36 pm


Help with antenna choice (small wideband?)

Hello everyone,
I am new to this RTLSDR thing, and I'm for now enjoying to capture ADS-B, FM, and some other strong bands around.
I'd like to make a standalone system with a "server" raspberry so that I can leave the antenna a bit higher, and for this I would like to have a better antenna.
My question comes because I am not sure what there are in terms of small wideband antennas, small enough and not ugly enough so my parents won't kill me :)
I leave here both potencial spots where I'd like to install the antenna.
Location 1
Location 2
I'd like to keep capturing said bands, and since it appears interesting would a small wideband antenna be able to capture Weather satellites or this requires different polarizations and direction?
Something similar to a whip antenna would be enough "camouflage" I would say. What kind of sizes are we talking about here?
Also, when should one play/worry with a motor to turn the antenna? I guess it's oriented for high directional antennas?
Regards

submitted by /u/sorama2
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Antennas • Re: Balanced antenna for direct sampling

WIth a 1/2 wave dipole you only get resonance at multiples of the dipole. e.g. if it's 40m in diameter (1/2 wave for 80) m then its more or less in resonance 40m 20 m 10 m wavelength, but the antenna pattern will vary with frequency and height above ground level.

Since you said you don't want to transmitt, why worry about missmatch of the antenna or getting it in resonance. A more or less long thin cooper wire, e.g. unwound from an old discarded transformer is easyer to install. I used for years a thin cooper wire that I stuck through a potato and then threw into trees or on roofs. With such a potato wire antenna you cannot damage anything, except glass. With a homebuilt transverter and my 2m transceiver I was able to receive signals from 77.5 kHz (DCF-77) upwards to 10 m. With an antenna matcher it also worked as transmitt antenna. I would rather look for a preselector to reduce the bandwidth you sample.

Statistics: Posted by snn47 — Sun Jul 22, 2018 7:38 pm


Comment on Tutorial on Setting up OP25 for P25 Phase 2 Digital Voice Decoding by AD5NL

Digital is definitely rolling out though. I’m in rural-ish Maury County TN and I believe both Spring Hill and Columbia (the two largrst cities in the county with about pop 40,000) are on digital now for the police. The County Sheriff and Fire/EMS are migrating but still have an analog simulcast.

Austin TX was on Phase I P25 when I left about six months ago. Ironically it might be harder to move larger systems than smaller ones.

GOES-16 setup help

I'm trying to put together a setup to recieve GOES-16 full disk and CONUS imagery, following pretty much every tutorial there is out there. My current setup consists of an rtl-sdr v3 dongle, NooElec SAWBird LNA, and 2.4Ghz grid antenna. Right now I'm picking up absolutely nothing, and while I have a few theories, I would definitely appreciate some help.

My first thought is that I should be using a 1.9Ghz antenna, not a 2.4. I'm not sure how I messed this up, but given this post by usa_satcom, it seems a 2.4 won't work. Is there any way to modify the antenna I have, or should I just return it and get a 1.9? I thought maybe adjusting the distance of the reflector might work, but so far that hasn't done anything. I also considered making a waveguide out of a can.

I also noticed in most posts that the feed antenna looks like 4 rectangular bars (secondary reflector?), where as mine looks like a cylinder. Now I know a little bit about antennas but it honestly isn't my forte, so I have no idea if this is important or not. What I do find interesting is that the picture of the antenna I purchased has the rectangular reflector... so I didn't really get what I ordered. Perhaps another reason to make a return.

(http://www.provantage.com/premiertek-ant-grid-24dbi~7PREK014.htm) is the one I bought, and this is what mine looks like.

The other thing I thought of is that maybe I'm too far north to get a signal, although I should see something, right? I'm in central Massachusetts, if that helps. As I understand it, farther north = bigger antenna required.

Anyway, thanks for giving this a read and if anyone has any tips I'd be very grateful!

submitted by /u/badcomponent
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Для радиохулиганов 21 века — …

Arduino — микромощный передатчик радиовещательного АМ-диапазона
Для радиохулиганов 21 века -
https://habr.com/post/415333/

Reverse Engineering a 2.4 ghz signal?

Hi I have a raspberry pi b+ that can act as a 2.4 GHz SDR. I want to use it to program the altierre electronic price tags used at Kohl's. How would I begin to find what I need to transmit to program them?

submitted by /u/rg422
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Troubleshooting Help • Re: ggrrr no Radio Sonde Decode

Why the Sound normal? :D
Sure if I stay wake I will record it tonight.

Statistics: Posted by Username — Sun Jul 22, 2018 3:02 pm


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