RTL-SDR Frequently Asked Questions

Dec 16, 2016

Answers, revelations, advice and recommendations for beginners new to affordable software defined radios.
Links open in a new window, post contains Amazon Affiliate links (you pay the same) and manufacturer review dongles, full disclaimer here.
This post is a work in progress, ask away in the comment section below.


Which is the recommended dongle to buy?


Nooelec SMArt (link to review) or rtl-sdr.com v.3 (link to review) in a bundle.



These two RTL-SDR receivers are purpose-built for radio signal reception, come with usable and quality accessories, good to go out of the box. Comparison between the two here.


Are generic dongles the same? They look the same.


No.



Read more here, in short, for $10 extra, you get a higher quality product with usable accessories and longer warranty.


I have no money


No problem.
If you can read this, you can read the internet, and information will help you to get really good performance for very small money.
You can get a very good RTL-SDR receiver for less than $10 dollars, which will be more than enough.
Wrap a piece of wire, length elbow to fingers around the screw on the small magnetic mount, put the mount on a metal tin, place it outside, and it will be good.

Which is the best software for RTL-SDR?


I find SDRuno has the best audio quality, but it's somewhat hard to learn how to use it - read my guide for beginners.
SDRSharp, also called SDR#, is quite popular due to ease of use, and some folks swear by SDRConsole.
There are many other for various platforms, but I mainly use SDRuno and SDR#.

Can I receive <insert service/frequency here> with RTL SDR dongles?


Google away, if the frequency in use falls between 22 to 1700 MHz, you can. If it's a digital service, you will need a decoding software.

Is <dongle name here> better than <dongle name here> ?


Define "better".
I don't know your preferences, so I can't answer the question. Ferrari or pickup truck? Ask a sports car enthusiast and a farmer, and you'll get two answers.
Dongles built for radio signal reception are better than re-purposed TV tuners, read the RTL-SDR Generations post for more info.


Which is the best dongle for ADS-B / airplane position signals?


FlightAware's Pro Stick Plus, review here.




Is <dongle name here> better performance than <dongle name here> ?


Realistically, the difference between a $10 dongle and a $20 dongle will be small.
All dongles use the same RTL2832U chipset, and the difference between two dongles, both using an R820T2 tuner, will be really small.
If you want a number, I don't think the receive performance difference between a $10 generic and $20 premium dongle will exceed 10%. A noisy shortwave signal will still remain a noisy shortwave signal on a $10, $20, and $40 dongle, but with a more expensive dongle you might have a fleeting chance of actually understanding, copying or decoding that signal.

I'm looking for a decent antenna / please recommend an antenna


Use antennas coming with your dongle, with modifications if necessary.
Alternatively, a discone cost from 60 to 100 dollars, expensive, but a one-time purchase.


Where should I put my antenna?


Preferably outdoors. If not possible, place it as close to a window as possible.


I can't receive anything! It's a ripoff! SDR sucks! etc.


Sentences or variations thereof come up so often it's comical.
" I've just bought an RTL-SDR for $90, comes with a small black probe which I think is the antenna, I've put that next to my screen. I want to receive weather satellites from my basement".
One last time:
- a dongle should not cost more than $40,
- that small black antenna is nearly unusable,
- place antenna outdoors or close to a window,
- weather satellites require a specific antenna,
- you'll only hear rats scurrying around from a basement.
Please read up on how radio works, helps a lot.


Can I listen to shortwave?


Yes, no cash method is called direct sampling, possible with cheap dongles, details here.
rtl-sdr.com v.3 dongle can do the same via software.
For best results, use an upconverter, like the Ham It Up v1.3.


How an upconverter works and how to use it


It adds ("up" in the name) a specific frequency to the received signal, so 10 MHz will be on 135 MHz with a 125 MHz upconverter.
I simply tune to 125 MHz and desired frequency for years when I use an upconverter, which I found easier than adjusting software.

Can I transmit with RTL-SDR dongles?


No.


Where can I buy equipment like adapters and cables?


Nooelec's and  rtl-sdr.com's online shop, Amazon, eBay.


Any secret dongle nobody knows about?


Not a secret, because I reviewed the FlightAware Pro Stick earlier.




Onboard LNA means a lot and makes the PS excellent value, but it doesn't come with an antenna. A telescopic for it costs a few dollars, so if you can remember that more gain does not equal more signal, go for it. If you can buy one.


Do I need amplification?


Not necessarily, but an amplified system will be better for weak signal reception.


Again, the "Which car?" question.
LNA4ALL is popular. More info on the maker's webpage.
I often use Janilab's LNA because it's easy to power with  micro USB aka smartphone connector.
I also use novakx5's LNA with great success, available on eBay.
LNA or preamp matters a lot if you have the proper antenna to go with it.


I want better receive performance


Everyone does.
Educate yourself, the key is the antenna and antenna positioning.
Receiver matters, but much, much less less than a good antenna for a frequency.
Experiment. Nobody knows what is a "good antenna", because textbooks rely on textbooks and PhD level assumptions.
Humanity has a vague notion of radio technology and physics and electricity, we simply don't know how and why stuff works.


What would be the most useful accessory?


A broadcast FM filter for about $15.



Commercial FM (~85 to 108 MHz) signals are so strong everywhere in the world that they can overload an RTL-SDR dongle, so the latest (and $150) SDRplay RSP2 has a built-in BCFM filter. The next best thing is buying one from rtl-sdr.com for $15, makes a huge difference.


Can I listen to the police / emergency services?



Depends on where you live.
In the US of A, it might be legal.
Rest of the world, it is either illegal, highly complicated, or both. Baby monitors also use the same technology, so I won't go into any more detail for moral reasons.
And I can't - I have no interest in decoding.
Before my local emergency services went digital nearly a decade ago, it was possible to receive them with a handheld comms receiver. The most boring conversations ever, if you want to listen to cops discussing what they did off-duty, like how to plant flowers (not joking) or who the Sergeant met in the pub, spend hours in front of a screen.
If listening to police sounds enticing, go to a striptease/chippendale club, it's more fun.


Portables or software defined radio?


Again, the "Which car?" question.
Portables do not require a computer, and will provide an eternity of signals on cheap batteries.
I use a Ham It Up v1.3 for a while, so confident stating that a 50 dollar portable simply does not compare.
I also have a Tecsun PL-680 and an RSP2, and the SDRplay is a better $150 spent.
Like it or not, traditional radios can not compete with digital signal processing when it comes to receiving a faraway signal. Manufacturers know this, so some of the latest knobs and buttons gear incorporate digital signal processing.
However, a $10 premium dongle can give a $300 traditional receiver a serious run for the money if used correctly.


Is a more expensive SDR better than RTL-SDR dongles?


Yes. Radio equipment is not different from other walks of life, you get what you pay for.
I only have experience with SDRplay's RSP1 and RSP2, and both are much better on many, many levels. For reception, I found that the HackRF performs about on the same level as a dongle, but the HackRF is not designed or marketed as a receiver, it's an engineering instrument.
Is a $150 SDR fifteen times better than a $10 dongle? Hell no.
Is it worth it? If you can afford it, then yes, if you can't, then start saving.

" I can't ..."


Yes you can.
There's a search engine called google. It's really useful if you can read.
There's a video sharing website called YouTube. It's really useful if you don't want to read.
Alternatively,
1. Read this site, there's a ton of information here.
2. Read rtl-sdr.com, there's a ton of information there.
3. Buy my book for $5 if you don't want to google your life away.
Proceeds go to maintaining this free website.

6 comments:

  1. Hey I bought U720 Analog Tv Tuner Geniatech company,I tried to replace the driver using Zadig but failed to replace it.I need to monitor 50 Mhz to 150 Mhz to listen to meteor pings please help

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    Replies
    1. I think that dongle doesn't work, must use RTL2832U chipset.

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  2. Great blog site! A fabulous resource for a newbie like me. I'm a sailor and interested in receiving weather and AIS signals. I live in Canada and I'm looking for the best dongle for monitoring AIS via a Raspberry Pi and viewing on OpenCPN?

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  3. Get a SMArt, 2m cable reaches from galley to cockpit without mods, antenna is usable for 162 MHz. Or a v.3 with bias-T and Uputronics AIS filtered preamp, bit more expensive at $60 shipped

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  4. is it possible to monitor airband using all rtl-sdr..?

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  5. Yes. E4000 chips are better than others on airband.

    ReplyDelete