• Search
  • Member List
  • Help
  • Random Thread

  • Tech Discussion Software Defined Radio
    Today I received the software defined radios that I ordered on eBay before Christmas.
    They were just $10 each, plus $2 shipping from China, so I bought three of them.

    [Image: sku_170541_7.jpg]

    Similar radios are available from Amazon for less than $20.

    They are elegant and simple.
    A USB dongle with an antenna connection
    The detachable antenna is included.

    Then you load SDR radio software on your PC, and you have a very fancy radio.
    The frequency range of the RTL2832U is roughly from 24MHz to 1860MHz.

    I installed the free SDRsharp (SDR#) software.
    You can download it here: --> http://sdrsharp.com/downloads/sdr-install.zip

    It looks like this:

    [Image: bad-image.png]

    The device driver installation instructions are available here: --> http://rtlsdr.org/softwarewindows

    The radios come with a tiny install CD and a remote control.
    Those are only for use with the digital TV system that is implemented in Europe, so do not install the software on the CD unless you live in Europe and wish to use it as a TV receiver for your laptop computer.

    I installed my first radio dongle and software on a Windows 7 Pro 64 bit laptop, but there are drivers and software radio apps available for these radio dongles for Linux and Mac OS X as well.

    So how do they work?
    The radio dongles basically contain two large scale integrated chips and a reference crystal oscillator.
    The first chip is a Rafael Micro model R820T.
    It is a crystal controlled radio tuner.
    The second chip is a Realtek RTL2832U.
    It is a programmable demodulator with a USB 2.0 interface.

    Under software control, the radio dongle presents a hunk of radio spectrum to the PC via the USB bus, and then the software does the rest.
    Which allows for such nice features as spectrum display and fast Fourier transform (FFT) waterfall plots of the observed spectrum over time.

    Since the low end cut off frequency of these radio dongles is around 24 or 25 MHz,
    you can not use them to listen to AM radio, or to the 160 meter through 14 meter ham radio bands.
    But you can listen to broadcast FM and all the VHF and UHF radio channels, including those used by aircraft.

    Never underestimate the power of human stupidity.
    - Robert A. Heinlein
    Some additional information regarding the software installation for this radio.

    When I first installed on my Windows 7 Pro 64-bit laptop, I had some problems.
    The SDRsharp radio software is 32-bit code, and needs to work with a 32-bit high level driver for the radio dongle.
    The Windows 7 OS is 64-bit, and will only work with a 64-bit version of the high level driver.
    This represented an apparently unsolvable problem.

    I found the following workaround:
    First use Zadig to install the low level Windows driver.
    Download the rtl_tcp software. Their web page is here: --> http://sdr.osmocom.org/trac/wiki/rtl-sdr
    Run the 64-bit version of rtl_tcp
    It will run in a command prompt DOS box, and creates a server for the radio dongle on TCP port 1234.
    Configure SDRsharp on the top drop-down menu to connect to RTL-SDR / TCP
    Click Configure. Host should be (local host) and Port should be set to 1234.
    Then the SDRsharp radio will work as soon as you click on Play.

    On machines that are running a 32-bit version of Windows, you won't encounter this driver incompatibility issue, and the instructions at the links provided in the top post will work like a no-brainer.
    The SDRsharp software lets you create a list of your favorite radio stations, so that you can return to them by just double clicking on their list entry.

    On my 32-bit Windows XP Pro office computer I now have the following software working with the radio dongle:

    HDSDR <-- radio software
    SDRsharp < -- radio software
    RTL1090 <-- 1090 MHz driver for receiving aircraft transponders
    ADSBsharp <-- 1090 MHz driver for receiving aircraft transponders
    ADSBscope <-- plotting software for plotting position of aircraft within radio range
    TVsharp <-- TV receiver for the now obsolete analog NTSC TV system that was used in North America

    These radio dongles lack sufficient bandwidth to decode the current ATSC (Advanced Television Systems Committee) digital TV signals used in North America.
    They typically only decode a 2 MHz hunk of the radio spectrum at a time. 3.2 MHz is their theoretical maximum.
    That is sufficient for the digital TV signals used in Europe, but not enough to meet the higher bandwith requirements of ATSC.

    There are special ATSC USB dongles available, but they are sold by the Americans, not by the Chinese, and they are three to 10 times as expensive as the inexpensive Chinese made Mini DVB-T + DAB+ + FM USB dongles that I bought.


    If you wish to connect the radio dongle to your Android tablet or phone, instead of to a computer, so that you can carry the radio around with you, then that is real easy to do.
    First, you need to get a USB OTG (On-The-Go) adapter cable. They are available from China on eBay for a couple of dollars.
    [Image: bad-image.png]

    You can also get them from Amazon for around $10 --> http://www.amazon.com/Electronics-Micro-...B005GGBYJ4
    You plug the cable into your phone or tablet, and plug the radio into the other end.
    Then you download and install the SDR Touch software for Android. You can get it here: --> https://play.google.com/store/apps/detai....androsdr2

    This is how it looks:

    [Image: F-givCIIUKyl3VtkCECUMfqx-MGKH4q1D9DvMseD...N021v=h310]
    (This post was last modified: 01-12-2014, 03:44 PM by velvetfog.)

    Never underestimate the power of human stupidity.
    - Robert A. Heinlein
    The inside of the dongle looks like this:

    [Image: SyeA5w8.jpg]

    The LSI chip on the left is the Rafael Micro T820 tuner and quadrature demodulator chip.
    Below it is a 28.8 MHz crystal in a metal can. This provides the frequency reference for the tuner.
    The other LSI to the right of it is the Realtek RTL2832U chip which contains the USB interface
    and the two high speed 8-bit analog to digital converters used for sampling the I and Q quadrature signals coming from the tuner.
    Next to the large USB connector is a 3-pin voltage regulator chip
    The other two chips are simple interface chips facilitating the interconnection between the two LSI chips.
    Then there is an electrolytic filter cap, and some discrete surface mount resistors and capacitors.
    To the left of the antenna connector is transistor to drive the LED above it. The clear plastic LED puts out blue light.

    The antenna connector is a gold plated MCX female coaxial socket.
    Inexpensive adapters are available on eBay to adapt this miniature connector to the more common antenna connector types.
    This makes it very easy to connect a different antenna to the radio than the little whip antenna supplied with it.

    [Image: bad-image.png]

    [Image: g1WPbjP.jpg]

    [Image: images?q=tbn:ANd9GcRQO4VlrQP1EukesBtM2ZZ...rNQHkwbWur]
    European type PAL/IEC connector used for cable TV

    [Image: bad-image.png]
    North American F type connector used for cable TV
    (This post was last modified: 01-12-2014, 06:04 PM by velvetfog.)

    Never underestimate the power of human stupidity.
    - Robert A. Heinlein
    I am very surprised they are not rip-offs of some kind or another.

    But I'm happy for you that you seem to have managed to buy an electronics product from China and did not get ripped off!

    That is not an easy thing to do these days.
    I have bought close to 300 separate items on eBay during the 14 years that I have had an account with them.
    The Chinese vendors that I have dealt with have all been courteous and prompt, and the items that they shipped me were exactly as advertised.
    The vendors that I have had problems with have all been located in the United States.
    The world has changed over the years. The Chinese have now become the world's foremost mail order suppliers.

    Shipping from China takes a while, usually three to six weeks.
    That is because most of the parcel volume from China arrives in shipping containers on the west coast.
    But their shipping charges are very reasonable, and often included in the item price.
    The Americans trading on eBay very often grossly overcharge on their shipping cost, trying to make extra profit on their items that way.
    I feel much safer dealing with the Chinese mail order houses in Hong Kong, Shanghai and Shenzhen, then I do dealing with individual American eBay vendors.

    In any case, when you have an eBay and a PayPal account, and pay for your eBay purchases via PayPal, you are fully protected.
    If the seller tries to cheat you, you just have to inform eBay and PayPal.
    They will resolve the dispute, and PayPal will refund your money if that is required.
    (This post was last modified: 01-12-2014, 11:42 PM by velvetfog.)

    Never underestimate the power of human stupidity.
    - Robert A. Heinlein
    (01-12-2014, 05:44 PM)velvetfog Wrote:  To the left of the antenna connector is transistor to drive the LED above it. The clear plastic LED puts out blue light.

    My mistake. The black item to the left of the antenna connector in the picture is not a transistor, although it kind of looks like one.
    It is the infrared receiver for the wireless remote control supplied with the unit.

    Never underestimate the power of human stupidity.
    - Robert A. Heinlein
    I found a web page with additional plugins that can be added to the SDRsharp radio software.
    I downloaded and installed most of them, which souped up the features of the software considerably.
    The link is here: --> List of SDRSharp Plugins

    Here is a video tutorial on installing and using SDR dongle radio software:

    Additional SDRsharp video tutorials are found here: --> http://www.youtube.com/results?search_query=SDRsharp

    I also downloaded the Orbitron software, which, when used in conjunction with the SDRsharp software radio, provides for reception from a large number of satellites.
    Orbitron can be downloaded here: --> http://www.stoff.pl/

    It looks like this:
    [Image: 4f1hnRF.gif]

    Here is a video tutorial for getting Orbitron to work with SDRsharp:

    I got it up and running last night. It is very neat.
    (This post was last modified: 01-25-2014, 03:29 PM by velvetfog.)

    Never underestimate the power of human stupidity.
    - Robert A. Heinlein

    Users browsing this thread: 2 Guest(s)
    Rant Central
    Speak Your Mind