RTL-SDR!!!

This summer I’ve been enjoying a new receiver which has terribly cheaply (for just 16.82€, or $19.20!!!!) joined the rest of my radio material. It is an ezcap ezTV645 DVB-T USB dongle and yes, you’ve read well, it is nothing more than… an USB dongle normally used to watch DVB-T TV broadcasts (DVB-T is an European standard for digital TV) in a computer!!! This highly performing device (specially when one considers its price) is my very first SDR (Software Defined Radio) receiver and has allowed me to have my very first succesful experiences in the SDR world!

The ezcap ezTV645 DVB-T Digital TV dongle.

It seems that USB DVB-T dongles work according to the same principle with which specific SDR USB dongles (the FUNcube Dongle being the only example) work. They use a tuner and an A/D (analog to digital) converter, which samples the output signal of the tuner, converts it to digital and sends it to the computer via the USB port. There, in the computer, a specific software takes this signal and carries out the demodulation task.

(More on SDR will be explained in a future entry; but let me only say that the advantage of SDR equipment is precisely this: to reduce the amount of physical electronic components to a minimum expression, as most of the work is carried out through software and not through “hardware” like “normal” receivers or transceivers).

Well, so what happens is that those (and for the moment, only those) DVB-T Digital TV dongles which contain both the Realtek RTL2832U A/D chipset (which gives this practice of SDR the name of RTL-SDR) and either the Elonics E4000 or the Fitipower FC0012, FC0013 or FC2580 tuners, through the use of special drivers, can be made to work as SDR receivers so as to listen to almost any kind of radio transmission in a vast (very, very vast…) frequency range.

The tuner which provides a wider frequency coverage is the E4000, from approx. 53 MHz to 2200 MHz, with a gap between, approx., 1113 MHz and 1244 MHz. The Fitipower tuners’ range is not as large, but they have an advantage in that they can receive lower frequencies. Also, and the same way it happens with the FUNcube Dongle, an external frequency upconverter can be connected between the antenna and the dongle so that all signals in frequencies below the dongles’ coverage, in bands such as HF and lower (in fact, as low as DC! :D ) are brought into the range of the dongles and can be received with them! Anyway, and using an upconverter or not (and like it happens with all SDRs), all kinds of radio signals can be received: voice (SSB, DSB, AM, FM narrow and wide), CW, even digital transmissions (such as GPS, ADS-B -which is used by aircraft transponders-, POCSAG; and ham digital modes such as APRS/Packet, D-Star, PSK, RTTY…) can be decoded using the proper software. Add to this that it is possible to display, in the SDR software, an in-screen reception spectrum with a bandwidth as large as 3.2 MHz (selecting a sample rate of 3.2 MSPS -Mega Samples Per Second-) and we have an astounding device!!!

A list of RTL-SDR compatible dongles can be found here.

At the beginning of the SDR experiments with these devices, they were used (in Windows) with known SDR softwares such as Winrad, HDSDR, or WRplus, through an external DLL controller, named ExtIO (which can be found here: http://wiki.spench.net/wiki/ExtIO_USRP). In Linux, the GNU Radio or gqrx softwares can also be used.

Recently, a new SDR program for Windows has appeared which adds a native support for RTL2832U-based DVB-T dongles. Its name is SDR# (read SDR Sharp) and it avoids the use of the ExtIO DLL which was pretty troublesome, while offering an excellent performance, and a lot of new functions (such as the demodulation of WFM -Wideband FM; used by the common commercial broadcast stations in VHF- in stereo!!!). It is a new software which is in constant development and including new functionalities, so be sure to check regularly its website (www.sdrsharp.com) for the latest released version. A good practice is to regularly download the newest version from here: http://sdrsharp.com/downloads/sdr-nightly.zip. To carry out the installation of SDR#, and of the driver which transforms the DVB-T dongle into a SDR receiver, detailed instructions can be found here.

Well, so focusing in my experience with RTL-SDR, I’ll say that my specific unit of dongle is, as I’ve already mentioned, an ezcap ezTV645, which contains the RTL2832U chipset and the FC0013 tuner. I bought it for just 16.82€ ($19.20) at dealextreme.com (http://www.dealextreme.com/p/mini-dvb-t-digital-tv-usb-2-0-dongle-with-fm-dab-remote-controller-92096?item=1). And although a small whip antena in a small magmount is supplied with the dongle, I quickly realized that it would provide a very poor reception to me (if I could receive anything with it), so I quickly discarded it. Instead, and to be able to use this dongle with any of the antennas I also use with my IC-R5 scanner (which connect to it through standard ham radio connectors: male SMA or male PL -with a PL-SMA adapter-) I homebrewed a simple antenna connector adapter, which is nothing more than a very short pigtail of RG-58 coaxial cable, with an European TV (“Belling-Lee”, IEC 169-2, or PAL) male connector in one end, and a female PL connector (or SO-239) in the other end. Also, I needed to perform minor surgery to the innards of the dongle. It happens that ezcap ezTV dongles are not supplied with an ESD (ElectroStatic Discharge) protection diode, although its location is clearly marked near the antenna connector in the circuit board. It is just like the factory had forgotten to add those diodes to the dongles… So I had to buy a pack of 10 BAV99 diodes at a local electronics store and carefully solder one of them in its correct location. Without this diode, using an antenna placed outside, which could very possibly be charged with static electricity as a result of the friction with the wind, would have supposed a risk too high of frying the dongle. There have been people who have destroyed their unprotected dongle’s electronics by just touching the antenna connector with a finger. So this ESD protection diode is a must! Thanks to it, I’ve been able to finally stop being forced to keep the antenna inside the house when using the RTL-SDR, and improve my reception conditions with it :)

Some pictures follow (click on them to enlarge):

The moment of the unpackaging, right after the arrival of the package at home.

The moment of the unpackaging, right after the arrival of the package at home.

The box containing the ezcap ezTV645 and accessories, right after going out of the package.

The box containing the ezcap ezTV645 and accessories, right after going out of the package.

The unboxing. Also visible is the TV-female PL adapter pigtail.

The unboxing. Also visible is the PAL-female PL adapter pigtail.

The ezcap ezTV645 DVB-T dongle, viewed from its aft end.

The ezcap ezTV645 DVB-T dongle, viewed from its aft end.

Detail of the female European TV connector in the back of the dongle.

Detail of the female PAL connector in the back of the dongle.

Closer detail of the female European TV connector in the back of the dongle.

Closer detail of the female PAL connector in the back of the dongle.

The standard USB port in the front of the dongle.

The standard USB port in the front of the dongle.

The whip antenna, mag-mount, and optional sucker, supplied with the ezTV645 dongle.

The whip antenna, mag-mount, and optional sucker, supplied with the ezTV645 dongle.

The homemade connector adapter pigtail, seen from its back end.

The homemade connector adapter pigtail, seen from its back end.

The homemade connector adapter pigtail, seen from its front end.

The homemade connector adapter pigtail, seen from its front end.

Closer detail of the European TV (IEC) connector in the adapter, which fits into the antenna connector in the ezTV645 dongle.

Closer detail of the PAL connector in the adapter, which fits into the antenna connector in the ezTV645 dongle.

Closer detail of the SO-239 connector in the adapter, where the coax cable from the antenna connects.

Closer detail of the SO-239 connector in the adapter, where the coax cable from the antenna connects.

The supplied antenna, screwed onto the mag-mount.

The supplied antenna, screwed onto the mag-mount.

The ezTV645 dongle with the homemade antenna connector adapter pigtail attached.

The ezTV645 dongle with the homemade antenna connector adapter pigtail attached.

The innards of the ezTV645 dongle. Detail of the FC0013 tuner. Also visible are the location of the missing ESD diode (at the left), and a 28,800 MHz crystal (bottom).

The innards of the ezTV645 dongle. Detail of the FC0013 tuner. Also visible are the location of the missing ESD diode (at the left), and a 28,800 MHz crystal (bottom).

The innards of the ezTV645 dongle. Detail of the Realtek RTL2832U chipset. Also visible are the IR remote sensor (at the left of the RTL2832U, not used in the RTL-SDR config) and the USB port (right).

The innards of the ezTV645 dongle. Detail of the Realtek RTL2832U chipset. Also visible are the IR remote sensor (at the left of the RTL2832U, not used in the RTL-SDR config) and the USB port (right).

The innards of the ezTV645 dongle. Detail of the back end of the European TV connector soldered onto the circuit board, and of the empty location of the ESD diode.

The innards of the ezTV645 dongle. Detail of the back end of the PAL connector soldered onto the circuit board, and of the empty location of the ESD diode.

The innards of the ezTV645 dongle. General view of the dongle's circuitry, with the FC0013 at the left and the RTL2832U at the right, between the IR sensor and the USB connector.

The innards of the ezTV645 dongle. General view of the dongle’s circuitry, with the FC0013 at the left and the RTL2832U at the right, between the IR sensor and the USB connector.

Detail of the female European TV connector, with the dongle uncovered.

Detail of the female PAL connector, with the dongle uncovered.

Comparison between the ezTV645 dongle, its cover, and a ruler.

Comparison between the ezTV645 dongle, its cover, and a ruler.

Comparison between the ezTV645 dongle, its cover, and a 3000 mAh NiMH rechargeable battery (standard AA size).

Comparison between the ezTV645 dongle, its cover, and a 3000 mAh NiMH rechargeable battery (standard AA size).

The innards of the ezTV645 dongle. View of the BAV99 ESD diode, soldered in its place the best way I could do it :)

The innards of the ezTV645 dongle. View of the BAV99 ESD diode, soldered in its place the best way I could do it :)

The innards of the ezTV645 dongle. General view of the dongle's circuitry, with the BAV99 ESD diode installed.

The innards of the ezTV645 dongle. General view of the dongle’s circuitry, with the BAV99 ESD diode installed.

The innards of the ezTV645 dongle. Detail of the back part of the circuit board, with the BAV99 ESD diode installed.

The innards of the ezTV645 dongle. Detail of the back part of the circuit board, with the BAV99 ESD diode installed.

Well, so after finishing these dongle-related operations, how well does it work? Well, I can say that all the times I’ve used it it has performed flawlessly. Running the great SDR# software (which lacks an S-meter in my opinion, something that would be a great addition) in a HP Pavilion dv6-3182es laptop PC originally intended for flight simulation (CPU: Intel I7 720 @1.60GHz; RAM: 4.00GB; OS: W7 Home Premium 64-bit) it flows fantastically: as smooth as silk. As long as I don’t select a sample rate value higher than 2.048 MSPS, which provides me with a displayed spectrum almost 2 MHz wide (with a higher sample rate value the audio starts stuttering), the operation of the software is very stable, and there are no stutters, no cuts in the audio, nothing strange at all. As far as the reception is concerned (and setting the gain at its maximum position), this cheap RTL-SDR dongle has demonstrated to me to have a surprisingly good sensitivity (not like my IC-R5′s acute “ear”, but close…). Another point to highlight would be the really great stereo audio quality when listening to a common VHF broadcast station. Also, I had never had before the ability to have all the activity in the entire 2m amateur radio band in view at the same time, or to simultaneously monitor the activity in all the LEBL (Barcelona-El Prat airport) approach (or ground, or radar…) frequencies in the air band. I also had never had before a receiver which by default came with the capacity to demodulate SSB signals, and this is very important to me, as it means that I’m able to, for the first time, listen to SSB satellites. I’m not restricted anymore to only picking the AO-27 and SO-50 LEO FM satellites, as well as the ISS; now I can also listen to the downlink of VO-52 at 145.900 USB!!! It is awesome to think of all the things that can be made with such a small (and cheap!) device…

Listening to the local VHF broadcast station RAC105.

Listening to the local VHF broadcast station RAC105. The traces of adjacent stations can be seen, as well as the huge bandwidth these stereo signals have. It is also possible to observe how the software is trying to decode the RDS information contained in the transmission. The discontinuity in the waterfall (where, in the moments of silence, the unmodulated stereo carriers can be seen) corresponds to the typical time signals (“beeps”) most stations use. (Click on the image to enlarge).

Monitoring the air band. LEBL (Barcelona-El Prat airport) Approach and TWR (Tower) sector communications.

Monitoring the LEBL (Barcelona-El Prat airport) Approach and TWR (Tower) sector communications in the air band. 118.100 is TWR for landings; 118.325 is TWR for takeoffs; 118.650 is the ATIS (Automatic Terminal Information System) for landings; and 119.100 is the Approach frequency. (Click on the image to enlarge).

Listening to a local QSO in the 2m ham/amateur radio band.

Listening to a local QSO in the 2m ham/amateur radio band. (Click on the image to enlarge).

Decoding the ISS Packet/APRS stream on 145.825!!!

Decoding the ISS Packet/APRS stream on 145.825!!! (+/- the frequency shift due to the Doppler effect) The Packet decoder software used is the UZ7HO Soundmodem available here. (Click on the image to enlarge).

Decoding the local terrestrial Packet/APRS signals, also with the UZ7HO Soundmodem software.

Decoding the local terrestrial Packet/APRS signals, also with the UZ7HO Soundmodem software available here. (Click on the image to enlarge).

Listening to the downlink of the ham/amateur radio satellite VO-52 as it makes its pass!!!

Listening to the downlink of the ham/amateur radio satellite VO-52 as it makes its pass!!! (Click on the image to enlarge).

The SDR nature of this receiver makes me able to see things I had never been able to see before!!!

The SDR nature of this receiver makes me able to see things I had never been able to see before!!! In this case I can actually take a look at the shape of a local and unidentified interference which appears in the afternoons. How cool is this. (Click on the image to enlarge).

There are some minor drawbacks, though: in a first place, a small impedance mismatch at the antenna connector of the dongle (which has the standard impedance for all commercial radio and TV equipment of 75 ohm, vs the 50 ohm impedance used in all ham radio equipment), which in theory causes a signal loss (however, this loss is very small, so it is not a big issue; and if necessary, I could solve it through the use of an 1:1.5 unun). Secondly, there’s a small delay in the sound, about half a second or so, in comparison to a conventional receiver such as my IC-R5 (which is the time taken in the process of converting the signal to a digital format, and transferring it to the computer via the USB port; it is not a big problem if I don’t listen to the IC-R5 and the RTL-SDR at the same time on the same frequency!). And in third place, it happens that a very strong signal in one frequency easily inhibits the reception in the rest of the displayed spectrum, this is, this receiver becomes easily saturated (even if the gain is at the minimums); again not a big problem, as strong signals, at my location, appear only sometimes; and it its something I can live with.

So what’s the conclusion? Considering its high performance, its wide frequency coverage, its reduced price and the new reception capabilities this brand new SDR receiving rig has personally provided to me, and also given the small relevance, in my personal case, of the drawbacks it presents, I’ll say that it is an outstanding device, very versatile and with a lot to explore. I extremely recommend it. Get an RTL-SDR dongle. It’s an awesome receiver!!! :)

raptor22stealth :)

About raptor22stealth

Aviation, space and radio listening enthusiast!!!
This entry was posted in Receivers & Radio Equipment. Bookmark the permalink.

38 Responses to RTL-SDR!!!

  1. David says:

    It was a very useful article for me. Thank you , David

  2. Jan Langevad says:

    Very useful for me too. Thanks.
    OZ8MS

    P.S. Can’t wait to get my DVB-T stick :-)

    • Thanks! As a student, these days I’m a bit busy so I can not update the blog as frequently as I would like, but I’ll say that these Christmas holidays I’ve received a brand new HF upconverter from CT1FFU… This and a homemade wire dipole will be the source for a lot of fun in the upcoming days!!! I’ll try to write an “RTL-SDR update entry” as soon as I can ;)

      (I also have to write some kind of a review for the Tecsun PL-600 receiver that has come these holidays too!!! :) )

      Rgds! David :)

  3. SV5BYR Mike says:

    Hello David,
    its a beatiful article. Can I use some comments and Pics for an article tha write for my Ham Magazine 5-9 Report ?? ( http://www.5-9report.gr )
    I will put you on the sources.
    73s de SV5BYR

    • Thanks for the comment! And of course you can, provided you mention me as the source for what you take from here. Feel free to use what you need! :)

      Rgds, David :)

      • Ken says:

        David,
        Thanks for the great site. I have (I think ) downloaded all the necessary stuff to make the dongle run. However, I still am unable to make the software work. When I click on the ExtIO button on the tuning display, it says it can’t find the dll file. I hav downloaded everything I ccan find and have put the dll file into the SDR install file. Can you point me to the resources on the web that are the most straighforward? Any help is appreciated, as I would really like to get this working. I’ve downloaded everything once – it wouldn’t work. Then I uninstalled everything and re-installed it.

        Also, the waterfall display is picking up ambient noise from the room, so the sound card isn’t configuring, either.

        Thanks,
        Ken/WB4EJZ

      • Hi Ken, sorry for the delay,

        First of all, what SDR software are you running? I don’t see any ExtIO buttons in SDR# or SDR Console, which are the two programs I use right now with my dongle…

        For the RTL-SDR dongles to work, you need the following “add-on” files:

        -For SDR Console (SDR-Radio) >>> http://v2.sdr-radio.com/Portals/0/Kits/SDR-RADIO-Pro_RTLDongleSupport.zip
        -For SDR# >>> http://sdrsharp.com/downloads/sdr-nightly-rtlsdr.zip

        Perhaps you are trying to run the dongle with the ExtIO dll using HDSDR or some similar software… I’ve got absolutely no experience with this combination, but what I can say is that as far as I know this is an older setup or a solution of compromise that was used before other software offered native support for RTL-SDR.
        If you install SDR# or SDR Console (or both :) ) you should be able to get the dongle running soon and with a better performance than when using the HDSDR-ExtIO.dll combination.

        Rgds,

        David – raptor22stealth

      • Ken says:

        HI,
        Thanks for the reply regarding the downloads. I re-downloaded SDR# and it all sprang to life! What a neat piece of technology! A lot of bang for the buck to boot!
        After having familiarized myself with amateur radio astronomy some years ago, I can see a definite application here – it easily covers the prime listening spot called “the watering hole” at about 1.42 ghz.
        Has anyone seen much traffic on blog posts or user groups on the use of the dongle for amateur RA?
        Thanks again.
        Ken

  4. S Frady says:

    What program would you use for digital modes such as PSK?

    • Hi, for the moment I’ve been trying the Digital Master software in the Ham Radio Deluxe set of applications. A couple days ago, I tried to decode some PSK-31 transmissions in the 20 meter band from a WebSDR receiver located in Andorra and I succeeded. Then, I connected the headphones output of my Tecsun PL-600 receiver to the microphone input in my laptop computer and, despite the noise that the laptop put on the receiver, the software did a nice job on decoding quite well the same signals. So a nice piece of software that, as far as I’ve been able to appreciate, works well.

      Also, there’s a whole lot of other software for decoding digital modes. One good page I came across about it is this: http://www.qsl.net/rv3apm/ . Check it out! One of these days I’ll have a try on some other software from this page to see how it works too.

      I’ve still not tried to decode from my RTL-SDR but I suppose that if it worked with the WebSDR it should work well too with the RTL.

      Hope that helped! :)

      David / raptor22stealth ;)

  5. JerryJ says:

    WOW! You know, if you sold pigtails like that, it may just be a lucrative little business. I haven’t been able to find one on the internet yet. Seems easily done, but TIME consuming. Lets put it plainly…I’d buy a couple from ya! Great article/post. Keep it up. Thanks

  6. sare says:

    Y por que no un Ezcap con el sintonizador E4000 o r820T? Tienen mejor rango que el FC0013 y

    • Era el sintonizador con el que me llegó cuando lo compré en Dealextreme, de todas formas y tras un tiempo usando un conversor para escuchar la HF (con más densidad e intensidad de señales que en VHF o UHF) con el “pincho” tampoco he notado que el FC0013 vaya excesivamente mal… sí, hay veces que se satura, pero eso yo lo atribuyo a señales fuertes en la banda y al hecho de que el bicho no tiene filtros…

      De todas formas, ya estoy pensando en comprar un “pincho” con el R820T, y así poder hacer pruebas y comparar…

      Saludos!

  7. aqkhan007 says:

    Can you plz tell me how to start with sdr#? Mine is showing RTL-SDR/ TCP but no usb option even I installed zadig. I’m using lastest nightly buid

    • Hi, sorry for the late reply and the general lack of blog activity, I’m a busy student and I still don’t have holidays… :)

      If you have installed the Zadig drivers now all what you need to do is to go to the “downloads” section in the SDR# website and download the “SDR# RTLSDR Plugin”. Overwrite the files in the folder where you’ve placed your SDR# with the ones in the zip file you’ve just downloaded (do not copy the “config” subfolder you will also find in the zip). Use the Notepad to open the “SDRSharp.exe.config” file located in your SDR# installation folder and do the following:

      In the “frontendPlugins” section, remove the marks that are disabling the line where the following text is present:

      add key=”RTL-SDR / USB” value=”SDRSharp.RTLSDR.RtlSdrIO,SDRSharp.RTLSDR”

      Now you should see an “RTL-SDR / USB” option in your device selection menu.

      Hope that helped!

      David / raptor22stealth :)

  8. Jaime says:

    Hola David: voy a recibir en breve el Terratec RTL2832U + E4000. ¿Qué conversor HF me recomiendas?. Se conectaría entre la entrada de antena y el Dongle, ¿no?.
    Saludos

    • Hola, exacto. El conversor se conecta entre la antena y el “pincho”, de manera que lo que éste ultimo vea no sean las señales de HF en sus frecuencias reales sino que, por decirlo de alguna manera, las vea “aumentadas” tantos MHz como aquellos con los que oscile (valga la redundancia) el oscilador local (OL) del conversor.

      Yo personalmente uso el conversor que vende CT1FFU, el de dos entradas. Me parece muy útil, ya que lleva un relé que, al quitarle la alimentación al conversor, conecta directamente una de las entradas con la salida de manera que no sea necesario desconectar dicho conversor de la línea de antena, para recibir señales en las bandas de VHF y superiores en dónde el “dongle” ya puede recibir por sí mismo. Simplemente es desenchufar el conversor del puerto USB que le esté dando los 5V, y listo. Además, esto posibilita el tener conectadas dos antenas simultáneamente, una para HF y otra para VHF y/o superiores, y commutar entre ellas con tan solo alimentar o no el conversor.

      Saludos!

  9. Herman L. Pickens says:

    I live in the US. Can I use the KWorld UB435-Q USB ATSC TV Tuner Stick?

  10. Nik says:

    Hi all, and very good article David!
    In hope to help some newcomer who would like to give it a try, here is some more useful info:

    - The best software to use IMHO is SDRSHARP, (http://sdrsharp.com/) . Here is a “magic” script from their website which will auto-download it and do the most part of setup for you:
    http://sdrsharp.com/downloads/sdr-install.zip .
    Unzip it in a folder then launch “Install.bat”. After that, don’t forget to run the “Zadig” utility to install the USB driver to complete your setup, or it will never work. You will find zadig.exe in “sdrsharp” folder after the script have finished setup, but FIRST read the easy explanation that you will find here:

    http://rtlsdr.org/softwarewindows

    - There are many RTL2832U’s based dongles, carrying several kind of tuners. The most famous combination is the RTL2832U + E4000 tuner, which seems to be able to tune the largest band (with a gap, as David already told). They are harder to find because the E4000 tuner is no more in production. BUT… I’ve tried many other tuners/USB dongles and I’ve found that the RTL2832U + R820T based dongles are far better than the E4000 based dongles. They are MORE sensibles vs faint signals, really. The reverse side is that they don’t cover frequencies over 1600 Mhz (but they starts around 22 Mhz, even if at that frequency there are many “dirty” signals coming -perhaps- from the pc. Need some filtering…).
    You can find many **cheaps** RTL2832U + R820T based dongles on ebay, coming mostly from China. They all works well, the only disadvantage is that they carry an MCX connector and so you will need some kind of adapter to connect it to an external antenna. Lately some seller will use to add some adapter to the bid, take a look for it. Or you can try cutting in the middle the cable of the mini antenna sold with the USB stick, and solder a BNC or a common TV or some other kind of connector to the other side of the cable connected to the MCX plug. Keep in mind that this will be a good solution for testing, but this cable doesn’t seems to be shielded so it will easily pick up some interference.

    - To decode digital modes, NOAA satellites and so on you must use appropriate softwares (some of them are free), and another one which is called VAC (virtual audio cables) (not free). The latter one is necessary to create an internal virtual connection from the audio output of Sdrsharp to the input of the decoding software.

    ————

    To Herman L. Pickens: sorry, no. As you can see here, http://www.linuxtv.org/wiki/index.php/KWorld_UB435-Q_USB_ATSC_TV_Stick , that stick is not DVB-T but is ATSC standard based, and it does not use the RTL2832U (which is responsible, along with the tuner, of this “magic” :) ).

    Happy SDR-ing!

  11. Eddie says:

    Hi, and thanks for this very intersting post.

    Thought you and your readers may be interested to hear that, after buying the EzTV645 recently, I opened up the dongle and found that it does have an ESD protection diode (marked A7W).

    The PCB is dated 2012-11-27, about 6 months later than the one you have here, so maybe their Quality Control finally got it together?

  12. Hola! Podrías decirme qué antena usaste para monitorear los canales de LEBL? Has probado diferentes antenas con el RTL-SDR? Qué tipo de antena recomiendas para experimentos varios (ADS-B, 2m, VO57, downlinks de la ISS, etc)
    Estoy ansioso por recibir mi RTL-SDR!!! :) Creo que voy a montar una antena díscona, pero escucho sugerencias! :)

    • Sé que sera un poco tarde, pero una antena tipo MSI ( http://www.pedrolo.com/index.php/antenas/proyectos-sencillos-de-antenas-caseras/49-antena-msi-mas-simple-imposible), cortada para 127 MHz (frecuencia centro de la banda aérea) debería ir bastante bien para escuchar. Como los aviones no vuelan tan alto como los satélites, aunque el lóbulo de radiación sea bajo la mayoría de las señales van a caer en él. Los aviones que pasen justo por encima de la antena caerán fuera de lóbulo pero dado que justamente pasarán por encima la intensidad de la señal cuando transmitan será suficiente como para que se escuchen bien también.

      Para ADS-B, una mini-MSI también, ajustada para los 1090 MHz, y usando un conector de panel tipo N, en lugar del SO-239, ya que este último empieza a rendir muy mal en frecuencias por encima de VHF, presentando pérdidas de señal notables. Yo he tomado la decisión de no usar conectores tipo PL/SO-239 por encima de HF si no es imprescindible.
      Para los 2m/70cm “terrestres” de radioaficionados yo lo que tengo es una antena Diamond SG7900 bibanda, que en teoría es para montar en coche, pero vamos, que por lo larga que es yo sólo la llevaría en movimiento si tuviese un camión xD. Por lo que le compré una base especial con radiales y la quiero instalar como antena de base sujeta a un mástil.
      Y para los satélites, tengo una antena del tipo “Turnstile” autoconstruida. Básicamente son dos dipolos a 90º y enfasados entre ellos de manera que el lóbulo de radiación, que se eleva hacia arriba (por eso es buena para sats) tenga además polarización circular y por ello se adapte lo mejor posible a la polarización cambiante de las señales procedentes de los satélites de radioaficionado (la mayoría de los cuales no dispone de sistemas de estabilización) que no paran de girar y dar tumbos en la órbita terrestre baja o LEO. Puedes leer sobre esta antena en: http://ea4eoz.blogspot.com.es/2012/09/the-turnstile-antenna.html . Yo la hice para VHF, pero sólo con recalcularla no es muy complicada hacerla para los sats que transmiten en UHF (70cm). Además, como hacia el horizonte tiene polarización horizontal y es omnidireccional, también es una antena de compromiso para DX, ya que los radioaficionados, en las bandas de 2m y 70cm y en los segmentos de las mismas dedicados precisamente a DX, usan precisamente la polarización horizontal dado que rinde mejor para propagar la señal si las condiciones atmosféricas lo permiten (esporádica E, conductos troposféricos… son fenómenos por los cuales frecuencias mayores de 30 MHz pueden propagar temporalmente a distancias mucho mayores de lo normal).

      Finalmente, aunque las disconos no son malas antenas, dice el dicho que “quien mucho abarca poco aprieta” y es eso exactamente lo que pasa con estas antenas. Aunque sean capaces de escuchar muchas señales en un margen muy amplio de frecuencias, no son especialmente sensibles ni presentan un rendimiento espectacular en ninguna de ellas. Mi modo de pensar es que es mucho mejor instalar antenas separadas para lo que quieras escuchar, y commutar entre ellas…

      ¡Saludos!

      David – EA4998URE SWL – raptor22stealth

  13. Suago says:

    I am interest to wonder if can use these SDR to make fish radar. Does anyone know of project that does fish radar. I prefer not make my own and get already made one but can make it if I have the plans.

  14. Sergey says:

    Thanks for this article! Now i am waiting for my USB dongle too :) It should be RTL2832/R820T, let’s see how this device will work.
    Sergey.

  15. Juan Barrada says:

    Hi. Thank you so much for this really clear and useful article! I’m just starting with SDR and this has been for me, by far, the most clear and useful help that I’ve found.
    I already ordered my USB dongle but, meanwhile, I’ve heard and read a lot about that the antenna that comes with the USB is not good at all. Have you worked on that? Do you have any advice about a good DIY antenna option for my new RTL DSR dongle? Thanks in advance for your help with this matter! Regards.

    Juan David

    • raptor22stealth says:

      Hi,

      Firstly, I need to apologize for not having been able to update the blog in a lot of time. I’ve not had a lot of free time during the past months and this prevented me from maintaining it.

      Secondly… Yes, you are right, the stock antenna that can be found with the dongle is very poor at receiving signals. Even at TV frequencies, for which the antenna is designed. I have to say that almost immediately after taking one of those whips out of the box I left it aside, but one day I decided to test it with my digital terrestrial DVB-T decoder and got no signals. I’ve not used any of them anymore… My advise would be the usage of any standard antenna that was cut for the center frequency of the band you want to cover. For example, in my case, I am currently using a Diamond SG7900 ham radio mobile antenna that is a dual bander designed to cover the amateur 2m (144 MHz – 146 MHz) and 70cm (430 MHz – 440 MHz) bands. I use it for listening to other VHF and UHF frequencies as well, because at the present moment I’ve not been able to install more antennas in my main QTH at Barcelona. For listening in the HF bands, I use an easy DIY antenna (not a great performer but like the ham radio saying, any antenna is better than no antenna at all): 12.6m of standard electrical copper wire, and a 9:1 unun. The unun lowers the high impedance the wire presents at some frequencies, to the 50 ohm impedance of the coax cable. The signals arrive then at an upconverter before being fed into my RTL dongle (the complete HF segment falls out of the coverage of those dongles and so the usage of a frequency upconverter is normally necessary). If for starting you would like to DIY something that is extremely easy and simple, and cheap to do, for bands from VHF onwards, I can recommend the “MSI” GP type antenna. You can find more about it here: http://www.pedrolo.com/index.php/antenas/proyectos-sencillos-de-antenas-caseras/49-antena-msi-mas-simple-imposible . The only materials required are: a SO-239 type connector, conductive copper or aluminum rod, power clamps, an a screwdriver. This is the antenna I made for covering the airband although I’ve not been able to install it yet! I had made it before for the ham radio 2m/70cm bands and it performed amazingly. I could even receive readable signals from ham radio satellites on low elevation passes. Try it!

      Hope it helped!

      David – EA4998URE SWL – raptor22stealth

      • Juan Barrada says:

        Que si me ayudó tu respuesta? … Muchísimo!

        Mil y mil gracias otra vez por tan valiosa información, ahora mismo empiezo a construir mi antena y sigo (des) esperando por mi dongle en el correo! (…hasta estoy pensando en adelantarme y comprar el diodo para mi receptor ahora mismo y así agilizar su muy casi segura reparación…jajaja!)

        Saludos cordiales desde Canadá!

        Juan Barrada

      • Juan David Barrada says:

        Hola, de nuevo Juan desde Canadá. Perdóname si te inoportuno con preguntas que pueden llegar a ser muy básicas para alguien con tantos conocimientos como tú, pero, en aras de intentar empezar a recorrer el mismo camino, me veo obligado a preguntar.

        Primero que todo, gracias por el link de la antena que me enviaste, la cual ya fabriqué por supuesto, ahora, (y esta es mi duda) quisiera saber que tipo de cable coaxial debo usar y cual es la mayor distancia a la que puedo conectar mi USB dongle sin sufrir muchas pérdidas (esto con el fin de alcanzar a poner a antena lo mas alejada posible de mi balcón el cual está rodeado de RFI).

        A modo de dato, pues no sé si esto tenga alguna incidencia sobre el coaxial que debo usar, te cuento que la antena estará conectada directamente al USB dongle, pero que muy pronto, tan pronto como el correo me lo permita, esta estará conectada primero al “Ham It Up” que ya he ordenado y este a su vez al USB.

        Saludos desde Canadá y otra vez mil gracias por tu invaluable ayuda!

        Juan David Barrada

  16. Hola Juan, en referencia a tu ultimo comentario:

    Pues el tipo de cable dependerá de las frecuencias que quieras escuchar, de lo que quieras escuchar en ellas, y de la longitud de la tirada de cable a emplear.

    Si es para VHF/UHF, y como mucho vas a querer escuchar señales locales (por ejemplo, señales en la banda aérea, o QSOs locales de radioaficionados en los 2m/70cm), puedes poner (las longitudes son aproximadas) hasta entre 6 y 6.5m de RG-58 (yo no pondría más, puesto que el RG-58 presenta una atenuación bastante alta) o hasta unos 17-18m de Aircell 5 (que es un cable del mismo diámetro que el RG-58 pero más rígido y con menos pérdidas). A partir de esa distancia sería necesario usar cables mejores, por ejemplo, Ecoflex 10 o incluso Aircom Plus. Son más rígidos y su diámetro es mayor (siendo más complicados de instalar) pero atenúan muy poco. Tengo una tirada de unos 20m de Aircom Plus, que aún está pendiente de instalación, pero un día la probé en la frecuencia local de Packet/APRS en 144.800 y mi escáner IC-R5 y la señal llegaba a fondo de escala, igual que sin esos 20m de cable. Por lo que este tipo de cable es muy recomendable para tiradas largas.

    Si vas a querer recibir satélites de radioaficionado, ten en cuenta que ellos no suelen transmitir con potencias de RF mayores a 5W como mucho (y normalmente con potencias de mW), ya que la potencia eléctrica a bordo es limitada (una excepción a ello es la ISS, que sale con unos 15W cuando se usa el transceptor Kenwood TM-D700 en el módulo ruso “Zvezda”). Por lo que la mayoría de las veces la señal que puede llegar a nuestra antena, especialmente si no es directiva (para hacer el seguimiento del satélite en su pase) es muy débil, y claro, no interesa perderla por el camino. Entonces, lo mejor es “curarse en salud” y directamente no usar RG-58 si no es para longitudes muy cortas de hasta unos 4m, y para tiradas de más de 13-14m pasar a Ecoflex o Aircom.

    Para HF, las pérdidas son mucho menores y cables como Ecoflex solo tienen sentido para tiradas muy largas, de quizás 25m o más.
    A la inversa, para SHF y microondas, lo mejor sería usar Aircell 5 sólo para tiradas cortas, y en cuánto al RG-58, ni pensar en él.

    O al menos esta es mi experiencia… piensa que no llevo tampoco tanto tiempo en esto de la radio (unos cuatro años y medio aproximadamente) y puede que me equivoque, pero de momento la práctica es lo que me dice ;)

    En el catálogo online de Universal Radio puedes consultar distintos tipos de cable y sus especificaciones: http://www.universal-radio.com/catalog/cable/coax.html .
    También en la página de la española Locura Digital: http://www.locuradigital.com/cables_radio/cables_radio.htm

    En cuánto al tener el cable directamente al dongle o al conversor, no hay diferencia alguna prácticamente. Piensa que la distancia de cable entre el conversor y el dongle es muy corta y prácticamente no atenúa, ¡aunque sea RG-174 que es aún peor que el RG-58!

    ¡Saludos!

    PD: Por cierto, si estás en Canadá, te interesará seguir los canales en YouTube de un SWL de Montréal, los cuales son https://www.youtube.com/OfficialSWLchannel y https://www.youtube.com/user/Officialvhfuhfchannel . Para mí, una de las referencias en Internet en lo concerniente a la radio :)

    • Juan David Barrada says:

      Hola David.

      Como en los casos anteriores, tu respuesta me ha sido de muchísima ayuda, me da una idea sobre por donde empezar…intentaré seguir tus consejos al pie de la letra, experimentando con las diversas marcas que me recomiendas, e iré depurando mi escogencia basado en los resultados que vaya obteniendo (al fin y al cabo de eso se trata este hobby!) . Gracias también por el link al canal de YouTube…está muy bien!

      (Y sobra decir que desde ahora…siempre estaré pendiente de tus aportes!)

      Saludos cordiales!

      Juan David Barrada

  17. You’re so cool! I do not suppose I’ve read through a single thing like this before.

    So good to discover someone with a few genuine thoughts on this issue.
    Really.. thank you for starting this up. This web site is one
    thing that is needed on the internet, someone with a little originality!

  18. For most up-to-date information you have to go to see world wide
    web and on internet I found this site as a best website for newest updates.

  19. Ray6K says:

    Hi there, great information! So thanks!
    Should be possible to swap the 50ohm connector of that dongle, with a 75ohm connector. I know 75ohm connectors are bigger, but they should have to fit if the plastic case of dongle is modded…
    what do you think about it? worth it?

    THANKS IN ADVANCE

  20. Wonderful site. Plenty of helpful info here. I am sending it to several pals ans additionally sharing in delicious.
    And of course, thank you in your sweat!

  21. You ought to be a part of a contest for one of the
    greatest blogs online. I will recommend this website!

  22. An intriguing discussion is definitely worth comment.
    I do believe that you should write more on this subject
    matter, it might not be a taboo matter but usually people do not
    discuss these subjects. To the next! Kind regards!!

  23. Hi there colleagues, how is everything, and what you desire
    to say concerning this post, in my view its actually
    remarkable in support of me.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s