Thanks, Ivan, for passing along another excellent project by Thomas (N1SPY). I love how simple this project is to put together and the fact that most SWLing Post readers, for example, likely have all of the components already! Great job, Thomas!
This morning, while browsing eBay, I noticed a high-production retailer selling an RTL-SDR package for $300 US! (To add insult to injury, this isn’t even the latest version of the RTL-SDR dongle!)
I post this warning message to those who are new to the world of the RTL-SDR.
You should never pay more than $30 US shipped for the latest version of the RTL-SDR dongle unless you’re buying custom enclosures, filtering, etc. In fact, the RTL-SDR package above retails for about $25 shipped via Amazon (though currently out of stock). The RTL-SDR stick alone retails for $20.95 shipped. You can find a number of models between $10-20 on Amazon and eBay.
The majority of eBay sellers list the RTL-SDR at the proper market price.
The allure of the RTL-SDR is its affordability–don’t fall for sellers on eBay, Amazon or elsewhere who list these at outrageous prices. They’re simply trying to rip you off.
I used the RTL-SDR Quick start guide at RTL-SDR.com/qsg. While I did not see any mention of Version 3, I hoped that the software that was linked would be adequate. As I am using a Windows 7 laptop, I downloaded the Zadig driver installer, along with copies of SDR# and HDSDR.
Getting the dongle going was pretty straightforward. And right away I was receiving VHF and above signals. The I/O driver defaults to Quadrature demodulation and this was what is used to receive VHF. But what about HF?
It took me awhile to figure out that you select Direct Sampling in the setup screen for the driver. In SDR# software this is found by clicking on the gear wheel icon.
Under sampling mode select Direct Sampling (Q branch).
In HDSDR you select the EXTIO icon.
Here you select the Q Input under Direct Sampling.
Note that with both you must use the Q input.
With the telescoping antennas included with the dongle, I received very few signals (of very poor quality). But I had read that the unit can only receive HF with a substantial antenna, so I moved the laptop to my hamshack.
I use an ELAD antenna distribution amplifier for my HF receive antennas.
It was easy to use a spare output from the ELAD ASA15 to drive the antenna input of the RTL-SDR V3.
Wow, what a difference!
First up was international shortwave. Here’s a shot from my Alinco General Coverage receiver on 9955 kHz this morning using my 260′ beverage antenna (pointed toward Europe). S9 on the Alinco S Meter.
And here’s the same signal on SDR#.
There was a delay in the audio coming from the PC versus from the receiver, but other than that, reception was identical. Audio quality was very good.
I then moved to the 20M Amateur Radio band. USB audio demodulation.
The little dongle worked! It is not what I would call my first choice in receivers, but it will demodulate AM and SSB just fine.
I did not try it on CW as I ran out of time.
I also tried the HDSDR software, which worked equally as well (but I think I prefer SDR# for ease of use).
All in all, if you have or can put up a good antenna for HF, the little $25 dongle is in, my opinion, worth trying out.
Thank you, Gary, for not only giving a quick evaluation of the RTL-SDR’s HF performance, but for describing how to setup HF reception via SDR# and HDSDR.
Over the years, I’ve gotten probably hundreds of emails from readers who would like to try their hand at SDRs, but were cautious about investing. For many years, a 3rd generation SDR would set you back at least $300-400. At $25 shipped, the RTL-SDR V.3 is an SDR receiver that is accessible to anyone who can afford a fast food meal or a few cups of Starbucks coffee. My how times have changed!
Once I get a few transceiver reviews off of my table, I might do some side-by-side HF comparisons between the RTL-SDR and a few of my other SDRs.
With Shortwave SDRs (the receiver dongle) now costing less than $20, the time has come for us to set up a global group of receivers that we can all log into at will!
Have a look at SDR.hu – here you can put your SDR dongle on line and share it with anyone and they have full control of the receiver just as if it was in their own shack.
Imagine receivers scatted around the world – South America, Tropical Asia, Africa! The cost is now virtually nothing, all that is needed is the dongle, antenna (doesn’t have to be anything special – even a long wire or whip) and a small low cost CPU (Raspberry Pi for example).
Anyone else interested in this dream? Lets get together, get some receivers setup and then talk about our experience in a kick-ass presentation at the 2017 SWL WinterFest in PA!
Also… I am very soon to receive my KiwiSDR matched to a BeagleBone CPU. It will be online at SDR.hu and four remote listeners will be able to tune the full shortwave bands independently, its like my own Twente setup! Heaps of others are getting receivers online in the next few months with KiwiSDRs, this is going to be totally amazing!
I agree, Mark! While there is already quite a network of remote SDRs and receivers in the world, the barrier of entry keeps getting lower and lower. It’s hard to imagine that $25 can buy an SDR that natively covers the shortwave and mediumwave bands!
There’s only one other requirement for an online SDR that Mark didn’t mention: a decent Internet connection. Sadly, this is the only thing keeping me from hosting a remote SDR here at my home. I considered purchasing a KiwiSDR like Mark, but my upload speed (0.2-0.3 mbps) is so terrible and so unreliable that I could only host one listener at a time at best. You can bet that as soon as my ISP upgrades our service, I’ll launch a web SDR as well.
Of course, I’m willing to bet that most SWLing Post readers have more than enough bandwidth to host a $25 remote receiver! Let’s make Mark’s vision a reality!
Many thanks to SWLing Post contributor, Ivan Cholakov (NO2CW), who shares the following video review of the new RTL-SDR dongle on the shortwave and mediumwave bands.
This is daytime reception comparison. Nighttime could be a different picture. [The RTL-SDR dongle] tunes and frequency is 100% on spot.
Using SDR Sharp you have several AGC settings to play with and find the best combination. The best setting seems to vary with band and signal strength.
The [SDR receiver] comes with a short (20 cm) and long (120cm) telescopic antennas. Neither one is usable for HF or Medium wave.
When ordering the radio you have to get a USB extension cord for the dongle. When plugged in directly into a laptop and then antenna coax it can become bulky. You also will most likely need an SMA adapter to BNC and SO 238.
Many thanks for sharing your video, Ivan! For a $25 SDR, I’m pretty impressed so far! I’m also very curious how it will hold up to stronger nighttime signals and, especially, adjacent signal interference. I imagine it may be prone to overloading as well. Please keep us posted!
Have any other Post readers tested the new RTL-SDR dongle on HF? If so, please comment!
I wanted to run SdrDx, and other SDR apps on my Mac with an RTL SDR Dongle. So I wrote this server app, that makes it appear like a networked SDR.
No need to install any RTL libraries, or compile any code.
Just run the app on your Mac, configure it and your SDR app, and you’re all set.
The app is free, and should work with Mac OS X 10.6 through 10.11.
Chris has kindly allowed me to share his full post here on the SWLing Post below–you can read the original at RadioHobbyist.org:
Running an RTL SDR USB Dongle On Your Mac The Easy Way With Cocoa RTL Server
I’ve had a few of the RTL radio tuner dongles for a while. These are USB devices that were originally made for use as TV tuners overseas, but it turns out that you can access the I/Q data stream, and turn them into an SDR (Software Defined Radio). They can be tuned roughly over a range of 25 to 1700 MHz, and sometimes even higher, depending on the tuner IC chip inside the particular dongle.
Fast forward to the present day. I got a new Mac running OS X 10.11 El Capitan, and I wanted to be able to use the RTL dongles with my favorite SDR software on the Mac,SdrDx. Enter Cocoa RTL Server.
Cocoa RTL Server is a stand alone app that interfaces with an RTL dongle. It does not require you to build or install any drivers or libraries. It just works. It’s based off of an open source app called SoftShell, that I heavily extended. Cocoa RTL Server also acts like a networked SDR, following the RF Space protocol. That means it works with SdrDx, as well as any other SDR app on the Mac that supports RF Space SDRs like the netSDR. You can download a copy of the app from the Cocoa RTL Server page. Source code is included, however I am not offering any support for the project or final app.
Here’s a screenshot of the app running:
Getting up and running is easy:
1. Plug in your RTL device
2. Run CocoaRTLServer 2.0
3. Select the device from the popup menu (usually it is already selected)
4. Change the rtl_tcp or tx_tcp port values if needed
5. Click Open
6. Configure your SDR app (set the correct TCP port) and run it
I’ve run it under Mac OS X 10.6, 10.10 and 10.11, It should run under 10.7-10.9 as well.
Using SdrDx, I can tune a large portion of the FM broadcast band, click to view full size:
In this case I am tuned to 97.9 MHz. To the left of the signal meter, you can see it has decoded the station ID from the RDS data. Yes, SdrDx decodes RDS.
If you look at the lower right corner, you see the scope display of the demodulated FM audio. There are markers for the portions of interest:
You can see the main audio above the green marker to the left.
The stereo pilot at 19 kHz (red marker).
The stereo subcarrier (aquamarine)
The RDS data (orange)
The 67 kHz SCA subcarrier (purple)
The 92 kHz SCA subcarrier (yellow)
Cocoa RTL Server also includes a server that emulates rtl_tcp, so it works withCocoa1090 which decodes aircraft transponders that transmit on 1090 MHz. It should also work with any other app that gets data from rtl_tcp. Here’s a screenshot of Cocoa1090 running:
Thanks so much for developing this app, Chris!
I think I might go ahead and pull the trigger on an RTL-SDR as it would be great to run one on my Mac. I think your app will make the process much easier.