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Earlier in this issue we told you about ADS-B and how you could monitor aircraft movements on your own computer screen. But how would you like to go one better: receive and display the actual ADS-B signals transmitted by planes as they fly over you? It’s easy – and once again, we’re using those bargain USB DVB-T dongles plus some free software. So it’s very low cost as well! Your oWN LOW-COST AIRCRAFT ADS-B RECEIVING STATION! By JIM ROWE . . . just mix in a PC, USB dongle, antenna, software and stir! B ack in the May 2013 issue of SILICON CHIP, we showed you how to use your PC as a software defined radio (SDR), using a low-cost USB DVB-T dongle plus some freebie software that can be downloaded via the internet. Then in the June issue we described a low-cost ‘upconverter’ which extends the bottom end of the SDR’s frequency range down to almost DC, so it’s able to tune right through the LF, MF and HF bands as well as the VHF and UHF bands covered by the basic PC-plus-dongle setup. 40  Silicon Chip Anyway, just as you may have thought we had exhausted the ‘extra’ uses of those el-cheapo DVB-T dongles, we were made aware of yet another very interesting use by Victorian reader David Padgett. David drew our attention to the way that at least some of the dongles can be used to receive the ADS-B ‘secondary surveillance’ signals we talked about earlier in this issue. And that this could be done very easily and at very low cost, using free software that can once again be downloaded from the internet. siliconchip.com.au One of the USB DVB-T dongles we found on ebay which fits the bill perfectly: it was being offered for the princely sum of $17.66 including postage or “make an offer” so we cheekily put in an offer of $15.00 – which was accepted! Its title on ebay is “DVB-T USB TV FM+DAB Radio Tuner Receiver Stick Realtek RTL2832+R820T” so they are making sure you know what you’re getting. Any dongle with this chipset should be fine for ADS-B (1090MHz) even if in the description it states that the range is only 48.25-863.25MHz. Which DVB-T dongle? Although you can use many different kinds of USB DVBT dongle for SDR (as long as they use a Realtek RTL2832U demodulator chip) you are a little more restricted when it comes to ADS-B reception. That’s because the frequency used by ADS-B, 1090MHz, is outside the range of some of the older dongles –‑ in particular, dongles using tuner chips like the Fitipower FC0012, which only tunes up to around 948MHz. Close, but no cigar! But if you have been using a dongle with one of the Elonics E4000 or Rafael Micro R820T tuner chips, these should be OK for ADS-B as well as SDR since these chips are all rated as tuning past 1090MHz. A dongle using the R820T might well be a bit better than the E4000 though, because the latter chips have a definite ‘gap’ in reception between about 1100 and 1250MHz and some tend to taper off in sensitivity before 1090MHz. Because of this a dongle using the E4000 may turn out to be fine for ADS-B reception, or it may be a bit ‘hard of hearing’. How about dongles using the popular Fitipower FC0013 tuner chip? Well, these can again be fine for ADS-B reception, as they are rated as tuning up to 1100MHz. But some of the FC0013 chips are a bit like the E4000s, with their sensitivity drooping a little before they reach 1090MHz. So dongles using the FC0013 tuner chip are usually well worth a try for ADS-B, but individual units might prove disappointing. Now what if you have not bought a USB DVB-T dongle at all as yet, and want to make sure you buy one now that will give good results for both ADS-B and SDR? In that case I’d suggest that you go for a dongle which uses the Rafael Micro R820T tuner chip, as this one seems to be widely regarded as giving the best results for ADSB. Make sure the dongle also uses the Realtek RTL2832U demodulator chip, though – this is just as important. If you look around on ebay, you’ll find a number of different low-cost dongles now being offered with the R820T/ RTL2832U chip combination specified, for below $30 (some much less). So one of these would be the way to go. There are also dozens of lower-price dongles being offered on ebay – for as little as $6-$7 or so (some including postage!). siliconchip.com.au Most of these don’t specify any particular chipsets (beware – may not work at all for ADS-B!) while many others specify the FC0013 tuner chip (which may be OK, as mentioned above). Because there are so many being offered, you can afford to be very choosey and get that R820T tuner – even if it costs you a little more. Also note that many state that their frequency range is only 48.25-863.25MHz. If it has the R820T tuner, you can be reasonably sure it will go significantly higher than this so is suitable for ADS-B reception. The antenna for ADS-B Choosing an antenna for ADS-B reception is a little different from what you need for SDR. That’s mainly because with ADS-B we are only interested in reception at one specific frequency (1090MHz), whereas with SDR we wanted to cover a wide range of frequencies. ADS-B signals from aircraft in your area – those you can see – are also fairly strong, so a modest antenna can give surprisingly good results – even indoors, near a window. But bear in mind that ADS-B signals are vertically polarised, so whatever antenna you use needs to be orientated to suit. Since a wavelength of 1090MHz is very close to 275mm, this means that you could go for a half-wave dipole (or ‘bow tie’, or bi-conical) antenna with an overall length of 137.6mm, or a quarter-wave whip just 69mm long. And many people seem to advise that whichever antenna you use, it should be located outside and as high as possible, away from trees and buildings. However, since I had on hand a couple of those ‘toy’ whip antennas that come with the el-cheapo DVB-T dongles, I decided to try cutting one of these down to an effective length of 69mm, just to see how it went. As supplied, these whips seem to have an effective length of about 130mm, so adapting them for ADS-B reception is basically cutting them down to about half-size. I did this by pulling off the small plastic ‘bumper’ at the top, sawing the rod to length with a small jeweller’s hacksaw and then pushing the plastic bumper back onto the cut end. So how did this ‘cut down quarter-wave toy whip’ go? Surprisingly well, as it happens, although I must admit that my location is only about 3km from Sydney KingsfordSmith airport (yes, they shake my place as they come in to land!). This 100-3300MHz “discone” antenna from Icom Australia (Cat AH8000) would be perfect for use at 1090MHz, the frequency used by ADS-B on all aircraft. It’s priced at about $100 and is available from Icom dealers around the country. (www.icom.net.au) August 2013  41 You can see the kind of results I was able to achieve using this very modest little antenna in the screen grab. Some of them were taken while I was using the ‘toy’ antenna inside, near my office window. Others show the results I got when I took the dongle and laptop outside into the back yard, with the ‘toy’ mini-whip placed up on the top of the rotary clothesline. Pretty impressive, wouldn’t you say? I also tried using my VHF/UHF discone antenna, as shown in the May article on SDRs (page 13). The results with this one for ADS-B were also fine, although possibly not quite as good as the cut down mini whip. So a cut down mini-whip antenna is likely to give you quite good results for ADS-B, even inside (as long as it’s fairly close to a window). I suspect the only way you’d get better ADS-B reception would be to make up a vertical half-wave dipole or ‘bow-tie’ antenna, mounted up fairly high - like at the top of your TV antenna mast. Even better, and something we are looking at for a future issue, is a “collinear” antenna for 1090MHz. The beauty of these is that you can keep adding sections for higher gain – and by definition, they are vertically polarised. You’ll find the web links for downloading each of these applications in the data box accompanying this article. Note that the ADS-B decoding applications just do the decoding, so you need to use one of the processing and display applications to complete your ADS-B receiving setup. Luckily you can ‘mix and match’ to a large extent, using either ADSB# or RTL1090 for the decoding and then either ADSBScope, Virtual Radar Server or PlaneSpotter for the processing and display. If you have two or more PCs on a network you can even have the dongle and decoding application on one computer and the processing and display application on another computer, with the decoded ADS-B data stream passing over the network. In the space available here we’re really only going to be able to cover the installation of the RTL-SDR driver together with one of the ADS-B decoding applications and one of the processing and display applications. The particular ADS-B decoding app we’ll be covering is ADSB#, and we’ll be coupling it to the ADSBScope app for processing and display. The all-important software Not surprisingly, the RTL-SDR driver must be installed before you can move on to install the application software. So if you haven’t previously installed the driver for SDR work (as described in the May article), you had better do this now. To help you, we’ll repeat the instructions given in the May article: The easiest way to install the RTL-SDR driver is by using an open source driver installer program called Zadig. Developed a couple of years ago by Pierre Batard, Zadig has been upgraded many times and is currently available as version 2.0.1.160 - in two forms, one for Windows XP and the other for Windows 7. They can both be downloaded (in self-installing exe form) from the web address given in the links box. Make sure to get the right one for the version of Windows in the PC you’ll be using for SDR. There is (currently) no version to suit Windows 8 – but then again, we haven’t found any USB dongles suitable for Windows 8 either! Note that both of these files are compressed in ‘7z’ archive format, so you won’t be able to extract the self-installing exe files with WinZip. They can only be extracted using 7-Zip, so you may need to download and install this first. Then you can download the correct (and latest) version of Zadig, after which you can use 7-Zip to extract the Zadig.exe installer file. Then you can run this file to install Zadig itself. Note that with Windows 7, you have to run the installer file as the Administrator – this is very important, as otherwise it won’t install Zadig correctly. With the hardware side clarified, let’s move on to look at the software side of what you need for ADS-B reception. As you might expect, the software is the key to ‘making it all happen’. You may recall from the May article that with SDR, there are two main software items needed: (1) a driver which allows the PC to communicate via the USB port with the Realtek RTL2832U demodulator chip inside the dongle; and (2) the application software which allows the PC to perform all of the necessary processing and display - in that case to perform as an SDR. The requirements for ADS-B reception are quite similar and in fact the first ‘driver’ item is the same. That’s because we again need the PC to be able to communicate with the Realtek RTL2832U demodulator chip. So if you have already installed the RTL-SDR driver for SDR work, there’s no need to install it again for ADS-B reception. When it comes to the ADS-B application software, though, there are a number of options. That’s because there are now two separate functions to be performed: decoding the ADS-B squitts and squitters being picked up by the chips in the dongle, then processing these decoded squitts so all of the aircraft currently ‘in view’ can be displayed on your PC’s screen together with all of their status information. There are several ADS-B decoding applications currently available for free downloading from the web. The two that seem to be the most popular are ADSB# and RTL1090, the first written by Youssef Touil and Ian Gilmour and the second by a group in Germany. If his name rings a bell, Youssef Touil is the same programmer whose team brought us SDR# and in fact ADSB# can be downloaded from the same website as before (see download links box). The alternative RTL1090 decoder can be downloaded from the website shown in the same box. There are quite a few other applications available for processing and display of the decoded ADS-B information. Three of these go by the names ADSBScope, Virtual Radar Server and PlaneSpotter. The first two are freeware but PlaneSpotter is trialware - you can try it for 21 days, but then to continue using it you have to buy a licence for 25 euros. 42  Silicon Chip First, the RTL-SDR driver Fig.1 Once installed, you can plug your DVB-T dongle into the USB 2.0 port you intend to use for ADS-B. Windows will siliconchip.com.au then go through its usual rigmarole, looking for what it thinks is a suitable driver for the dongle. Don’t worry if it does this though, because you’ll be using Zadig to install the correct RTL-SDR driver shortly. Now start up Zadig in the usual way. With Windows XP, you should immediately see a window similar to that shown in Fig.1. With Windows 7, you’ll almost certainly get a User Account Control window first, asking you ‘Do you want to allow the following program to make changes to this computer?’ and listing the Program name (Zadig), the Verified Publisher (Akeo Consulting) and the File Origin (Hard drive). You’ll have to click on the [Yes] button before Windows 7 will let Zadig run, to display the same startup window as in Fig.1. Next click on ‘Options’ in the top menu bar and you should see a drop-down menu like that shown below (Fig.2). horizontal bar, as shown in Fig.4. However at this stage it probably won’t show anything in the text box just to the right of the ‘Driver’ label, or else it’ll be showing whatever driver Windows installed (or tried to install) when you first plugged the dongle into a USB port. Either way you probably will see text items in the two smaller boxes to the right of the ‘USB ID’ label, rather like the text that can be seen here in Fig.4: Fig.4 Fig.2 Click in the blank area just to the left of ‘List All Devices’ and the drop-down Options menu should disappear. But there should now be some text displayed in the main dropdown menu bar, probably for one of your USB devices like a mouse, keyboard or printer. And if you now click on the ‘down arrow’ at the right-hand end of this menu bar, you should get a drop-down list of all of the USB devices that Zadig has been able to find connected to your PC (as shown in Fig.3). Fig.3 Look down through this list to find the DVB-T dongle which you have plugged into one of the USB ports. The only catch here is that depending on the dongle, it will be listed under various different names. Some dongles may appear as ‘RTL2838UHIDIR’ as shown highlit at the bottom of the list in Fig.3, while others may be shown as ‘Bulk-In, Interface (Interface 0)’. Still others may appear as ‘RTL2832U’ or similar. The main things to look for are either that ‘Bulk-In, Interface’ label or one starting with ‘RTLxxxx’. When you spot the dongle in Zadig’s list, click on its entry so that it becomes highlighted. Zadig should now display the dongle’s label in the main siliconchip.com.au Now turn your attention to the large blue rectangular button at the lower centre of the Zadig window, which will probably be displaying the text ‘Reinstall Driver’. If it isn’t, click on the downarrow at its right-hand end to find Reinstall Driver in the drop-down list. Then once the text is displayed in the main part of the button, click on this button to set Zadig to work installing the correct RTL-SDR driver. After whirring away for a few seconds, Zadig should display a ‘Successful Install’ message and then you should see the correct driver name displayed in both the text box just to the right of the ‘Driver’ label and also in the box further to the right, just to the right of the large green arrow. (You can see the driver displayed in this box in Fig.4) Use the same USB port! The driver should now have been installed correctly, and should be called up automatically whenever your dongle is plugged into the same USB port at a later time. So if you always plug the dongle into the same port when using it for SDR, you shouldn’t have to fire up Zadig to reinstall the driver again. But note that Zadig only installs the SDR driver linking to the dongle via that particular USB port; if you plug the dongle into another USB port, you’ll have to run Zadig again to reinstall the driver for that port. Now that Zadig has installed the SDR driver, you can exit from it by clicking on the red button at upper right (the one with the usual red ‘X’). But before you move on to download and install the ADS-B application software, it’s a good idea to go into Control Panel > System and Security > Device Manager to make sure the driver has been installed correctly. Down near the bottom of the list of devices, you should see a subheading ‘Universal Serial Bus Devices’ as shown at lower left in the screen grab overleaf. Then when you click on the arrow to the left of this subhead, you should see a device with the same name as you’ve seen previously in Zadig (it’s shown as ‘RTL2838UHIDIR’ above). This will be your dongle, and if you then right-click on this device name and select ‘Properties’, you should see another small indow open up like that shown on the right in Fig.5. If August 2013  43 Fig.5 you then click on the Driver tab in this window, you should be presented with the details of the driver that Zadig has installed for it. As shown above, the Driver Provider should be shown as ‘libusbx.org’, and the Driver Version as ‘6.1.7600.16385’ (or another number if it has been updated from the current version). If all seems well so far, it’s likely that Zadig has correctly installed the RTL-SDR driver for your dongle, and you’ll be ready to proceed with installing the application software. So you can back out of Device Manager and Control Panel and return to your desktop. ADSB#, the decoding app The next step is to download and install the ADS-B decoding application, in this case ADSBSharp. This can be downloaded from the website shown in the links box, and as you can see it comes in zipped-up form. You then need to create a new subfolder in your Program Files folder (like C:\Program Files\ADSBSharp), extract the files from adsbsharp.zip using Winzip and copy them all to the new subfolder. Then when you use Windows Explorer to look at the files on that subfolder, you should see the list as shown in Fig.6. Fig.7 that will be used to communicate with your processing and display app (the default port number is 47806, as visible in the grab below). This should be left with the default number. Below the main Start/Stop button is a small button with the caption ‘Share with ADSBHub’. There’s no need to click on this button unless you’re going to be sharing the output from ADSB# with other PCs on your network, or with sdrsharp.com via the internet. Moving down, you’ll see the caption ‘Decoder’, with two text input boxes labelled ‘Confidence’ and ‘Timeout (sec)’. Inside the input boxes there will be default values for the confidence level that ADSB# will be using for decoding ADSB signals (‘4’ indicates that it will need that many ADS-B packets from a single ICAO ID target, before it recognises that Fig.6   ADSB# is clearly visible at the top with its little ‘radar screen’ icon, with the name ADSBSharp.exe. This is the decoder program itself, and if you double-click on it the program should fire up to display the small control window visible on the left as seen above right in Fig.7. As you can see, the ADSB# window isn’t nearly as ‘busy’ as the one for SDR# which we looked at in the May article. It has a rectangular button at upper left with a blue border, which is clicked on to start or stop the application. Then there’s a text box at upper right showing the IP port number 44  Silicon Chip Fig.8 siliconchip.com.au target as valid); and the time it will allow between packets from a single target before it must pass the Confidence filter again (so ‘120’ means if there are no further packets from that target for 120 seconds, ADSB# will regard it as ‘gone’, and it will have to start all over again to be recognised). Further over to the right you can see a label ‘Frames/ sec’, with a bold numeral (initially zero) underneath. When ADSB# is started up shortly by clicking on the Start button at upper left, this number should build up as the decoder finds ADS-B data frames. Since the number shows how many of these data frames are being received each second, it can be useful for comparing the performance of ADS-B antennas and also for finding the optimum RTL-SDR frequency correction for the dongle being used. More about this in a moment. siliconchip.com.au As you can see, the lower half of the ASDB# window is concerned with controlling and optimising the RTL-SDR driver settings, and consequently ‘tuning up’ the chips in the dongle. At the top of this section is the label ‘RTL-SDR Control’, plus the label ‘Device’ above the left-hand end of the long horizontal text box. Inside the text box there should be the name of the dongle you have installed the RTL-SDR driver for, like the ‘ezcap USB 2.0 DVB-T/DAB/FM dongle’ visible in the box in Fig.7. You may have already noticed that the tuner chip in the dongle is also displayed above the right-hand end of the text box (here it’s ‘E4000’). By the way if the name of your dongle is NOT displayed already in the text box, you need to click on the small ‘down arrow’ at the right-hand end of the box, which should cause a drop-down list to appear. You should then find your dongle’s name in this list. If you click on it, ADSB# should then display its name in the main text box and make it the one being used. Just below the main text box you’ll see two square ‘radio buttons’, one labelled ‘RTL AGC’ and the other ‘Tuner AGC’. Then below these is a horizontal slider bar, labelled ‘RF Gain’. These three controls are all provided to allow you to manage the raw RF gain of the chips in your dongle, and also the way its AGC is operating. You can of course experiment with these controls to see which ‘recipe’ seems to work best, but my suggestion is that you simply drag the RF Gain slider to the right-hand end, and then click in the ‘Tuner AGC’ square button so that tuner chip AGC is enabled. This will cause a small tick to be displayed in the button, as you can see in Fig.7. The one remaining control on the ABSB# window is down at the bottom, labelled ‘Frequency Correction (ppm)’, with a text input box to its right. If you have been using SDR#, this will be familiar to you since SDR# provides exactly the same control. As before the idea is to allow the application to make a correction for any frequency error present in the dongle’s crystal oscillator. Most of these do have a small frequency error, so by correcting for it we can make sure that when ADSB# tunes the dongle for reception at 1090MHz, it really does tune to this frequency. Now if you have already been using your dongle with SDR#, you have probably used SDR# to find the dongle’s frequency correction using the simple technique we discussed in the May article. So before you start up ADSB#, it’s a good idea to type the correction into the text box (with a minus sign if it’s negative). Or you can click on the up or down arrows at the end of the box, to get to the correction figure incrementally. As you can see in Fig.7 the dongle I was using when this grab was taken needed a frequency correction of -67ppm (parts per million). Of course if you haven’t found the dongle’s frequency correction using SDR# and don’t even have it installed on the PC you’re going to be using for ADS-B reception, you can’t feed a correction into ADSR# at this stage. So leave the correction figure set to the default ‘0’, and then you can change the setting later when ADSB# is running, to achieve the highest Frames/sec reading (at centre right). This is the ‘trial and error’ approach to correcting for the dongle’s frequency error. At this stage you should be ready to click on ADSB#’s Start button at upper left, to set it running. If all is well so far, you should see the Frames/sec figure start to build up at centre right as ADSB# decodes the ‘squits’ and ‘squitters’ August 2013  45 Downloading ADS-B software To install the RTL-SDR driver, you’ll need Zadig (available in two versions, to suit Windows XP or Windows 7). Download these (as self-installing exe files) from: sourceforge.net/projects/libwdi/files/zadig Note however that whichever of the two versions of Zadig you get, it will be compressed in the “7z” archive format. Since this means they have to be extracted using 7-Zip rather than Winzip, you may need to download and install 7-Zip first (unless you have already done so previously). 7-Zip can be downloaded either from either sourceforge.net or www.7-zip.org, but note that it too comes in two versions – one for Windows XP and the other for Windows 7. ADSB decoding applications: ADSB# can be downloaded from http://sdrsharp.com/downloads/adsbsharp.zip A Quickstart guide for ADSB# written by Henry Forte can be downloaded as a pdf file from: www.atouk.com/wordpress/?p=247 RTL1090 can be downloaded from http://rtl1090.web99.de/ ADS-B processing and display applications: ADSBScope can be downloaded from http://www.sprut.de/electronic/pic/projekte/adsb/adsb_en.html #downloads Virtual Radar Server can be downloaded from www.virtualradarserver.co.uk PlaneSpotter can be downloaded from www.coaa.co.uk/planespotter.htm from aircraft in the surrounding sky. (If the figure doesn’t seem to be building up, you may either have an antenna problem or else you’re going to have to play around with the dongle’s frequency correction at lower right, because it isn’t tuning close enough to 1090MHz.) Or it is possible that there are no planes in your area close enough to receive. The buildup in ADSB#’s Frames/sec figure is the only indication you get that the application is running, apart from the legend in the button at upper left changing from Start to Stop. Since this is not all that reassuring, you may want to try firing up Windows’ Telnet utility, which can show you the decoded ADS-B data streaming from ADSB#. This will let you make sure that ADSB# is fully functional before you install and run the ADS-B processing and display application. In case you’re not familiar with Telnet, it’s a simple IP text terminal utility which is included with Windows XP. In the case of Windows 7 it is also present but must be activated before it can be used. To do this, begin by clicking on the Start button and then on Control Panel. Click on Programs, and then click on Turn Windows Features on or off. You may be prompted for administrator confirmation, but if so just do this and you’ll be presented with the Windows Features dialog box. If you select the Telnet Client check box and then click the OK button, Windows 7 will download Telnet from the Microsoft website and install it ready for use. Once you have Telnet available it’s not all that difficult 46  Silicon Chip to use it to display the data stream coming from ADSB#. Here’s the procedure: Click on the Start button at lower left, and then click on the Run... icon. This will open up the Run dialog box, with the label ‘Open:’ followed by a text input box. Type in ‘telnet’ and click on the OK button. Telnet’s command line window will then appear on the desktop, with the title C:\WINDOWS\system32\telnet.exe across the top. There’s then a greeting message in the box itself, followed by a brief explanation of how to leave the program and finally the command line: Microsoft Telnet> Now type this command (note the spaces between the three fields): open 127.0.0.1 47806 and hit the Return/Enter key. If ADSB# is running you’ll see a long listing of the decoded data coming from it, as shown in the right-hand window of Fig.7. The data is displayed in hexadecimal strings, with each string preceded by an asterisk and ending with a semicolon. Ordinary Mode S transponder squits are of 14 hex digits (i.e., 56 bits of data), while the extended squitters from aircraft with an ADS-B transmitter are of 28 hex digits (= 112 bits of data). So if that’s the sort of listing you see, you can be assured that ADSB# is running as it should and decoding the ADSB data being received by your dongle. You can now stop ADSB# by clicking on the Stop button, whereupon Telnet will report that: Connection to host lost. Press any key to continue... Then if you do press any key, it will return to its command line. All you need do to exit from Telnet and close it down is to type in ‘q’ and then hit the Return/Enter key. You’ll now be back at your desktop, and ready to install the last link in your ADS-B receiving chain: the processing and display application. ADSBScope, the display application The ADS-B processing and display application we’re going to discuss here is ADSBScope, which can be downloaded from the website shown in the Download Info box. When you go to that website and folder, you’ll find there’s a choice of two versions. I suggest that you select and download the file under the heading ‘Regular Version 2.6’, described in the link below the heading as: ZIP-File with all relevant data (13MB) If you click on this link, you’ll begin to download a file called adsb_all.zip, containing not only all of the app’s binary files but also a couple of PDF files, one a ‘Quickstart’ manual and the other a more elaborate manual with more info regarding ADS-B reception with a DVB-T dongle, antennas and so on. The English in these manuals is a bit hairy and ‘Germanic’ but they’re reasonably informative. So when you have downloaded the adsb_all.zip file to a temporary folder, extract all of the files into the same folder. This is a good time to print out the two pdf files, so you’ll have them for reference. Then open the subfolder pc_software, and you’ll see a further subfolder called adsbscope. If you open this you’ll find yet another subfolder called 26, and this contains the application you want and all of its own subfolders. The next step is to create another subfolder in your Prosiliconchip.com.au gram Files folder where ADSBScope is to be installed (like C:\Program Files\ADSBScope\). Then you can copy all of the files and subfolders in the downloaded 26 subfolder into this new ADSBScope subfolder. Now, if you look in your newly created C:\Program Files\ ADSBScope\ folder, you should find two executable files: adsbscope26_16384.exe and adsbscope26_256.exe. These are two slightly different versions of the app, differing only by how many aircraft they can track simultaneously (256 or 16,384). So to get ADSBScope up and running, simply double click on either one and in a few seconds you should see its main window – a bit like the one shown in Fig.8, although at this stage the map shown in the graphical display window on the left will probably show an area around Prague, in the Czech Republic. (This is ADSBScope’s default location.) The other data fields over on the right will probably all be blank as well, although there may be a bit of general information displayed in the small upper text box. By the way before you actually start up ADSBScope, you should start up ADSB# so that it is delivering a decoded ADS-B data stream for ADSBScope to work on. Now the first thing to do when you have started up ADSBScope is to advise it of your actual location (assuming you don’t live in Prague, that is). To do this, click on the Navigation menu heading at the top. This will bring down a drop-down dialog like that shown in Fig.9. You should find then that the centre of ADSBScope’s graphical display will switch from Prague to the centre of your selected city or airport. However it will probably have a black background, so if you click on the eighth button from the left (the one with a small ‘world globe’ icon on it) in the top row above the graphical display window, as shown in Fig.11. ADSBScope will search Google maps and replace the black background with a colour map of your area. Fig.11 You need to make sure that ADSBScope regards this location as your new default location, rather than Prague. So go back to the Navigation menu, and click on the ‘set Receiver Location line at the top (you can see it in Fig.9). You’ll find that ADSBScope will display a ‘WARNING!’ dialog, as shown in Fig.12. But since changing the receiver location is exactly what you do want to do, simply click on the OK button and it will do the job. Fig.12 Fig.9 Then click on the line labelled ‘goto Town or Airport...’, which will open the dialog box shown in Fig.10. Now you need to tell ADSBScope how to establish a link to your source of decoded ADS-B data, which in this case is ADSB#. To do this, click on the ‘other’ menu title on the top menu bar (between ‘Navigation’ and ‘decoder’). This will provide the drop-down menu shown in Fig.13, and if you then click on the ‘Network’ line at the top, another flyout menu will appear at the right (as also shown in Fig.13). Fig.10 This has two long scroll-down lists, one for cities and towns on the left and the other for airports on the right. Scroll down one or other of these lists, until you find your city or airport. Click on that name or airport code to select it, and finally click the Close button. siliconchip.com.au Fig.13 Now click on ‘Network setup’, at the top of this secAugust 2013  47 ond menu. You will then be greeted by the Network setup dialog shown in Fig.14. There’s no need to worry about most of the options and information visible in this dialog, because ADSBScope’s programmer ‘sprut’ has thoughtfully provided some preset decoder ‘recipes’ down near the bottom of the dialog. There’s a preset provided for ADSB# – so if you click on this preset button, ADSBScope will fetch the preset data for ADSB# and change the settings to those you see in Fig.14: Portnumber 47806, URL 127.0.0.1 and ‘normal’ data format rather than ‘binary’. Fig.14 So if that’s what you see in the lower half of the dialog after clicking on the ADSB# button, simply click on the Close button at the bottom to close the dialog and save the decoder link information. At this stage you should make sure that ADSBScope will ‘remember’ all of this setup information, so that it becomes the default every time you start up ADSBScope in the future. So click on the File menu button at top left, which will produce the drop-down file menu you can see in Fig.15. Then all you have to do is click on the ‘save default’ line, and ADSBScope will save the complete current setup as its default. At this stage ADSBScope has been setup for operation at your location and with your Fig.15 decoder, but nothing much will appear to be happening because it still hasn’t been told to ‘get going’ by linking up to the decoder’s data 48  Silicon Chip stream. Luckily this final step is very easy: all you have to do is click on a button in the top row above the graphical display window – the one with an icon showing five little PC’s in a ring, just below the Navigation menu. If you pass your mouse over this button, you’ll see the clue text as shown in Fig.16 (‘start RAW-data CLIENT’). So click on this button, and you should see ADSBScope spring into life. Within a few seconds, you should see aircraft starting to appear in the graphiFig.16 c a l d i s p l a y, a n d matching information on the aircraft will be appearing in the larger text window on the right. You’ll probably also see the decoded hex information coming from ADSB# in the upper text window, although you may need to click in that window for it to appear. Down in the smaller text window you should also see the fully decoded ADS-B and Mode S data, although if this doesn’t happen (and you don’t even see a lower text window) you need to click on the button at the top of the screen with an icon showing a hand writing in a notebook with a pencil (just to the right of the one with an open book and question mark). If you pass the mouse cursor over this button you’ll see the clue text ‘show decoded data’. But when you click on this button, a lower text window will appear with the decoded data scrolling past. So everything should now look rather like the screen grab in Fig.8, although the details will of course depend on your location and the aircraft ‘in view’. You have now fully installed and set up ADSBScope, and your ADS-B receiving station is fully operational. You’ll find that ADSBScope has many more features than we’ve looked at here, but you’ll have to read the author’s Quickstart manual and his more complete manual, for more information on making use of them. There’s plenty of opportunity for experimenting. Comparing antennas To end up (and hopefully whet your enthusiasm), there are two similar screen grabs shown in this article. The display on the opening page (p40) shows my setup with ASDB# linked to ADSBScope, using a dongle with an E4000 tuner chip and a cut-down mini-whip antenna. The only difference between this screen grab and the one in Fig.8 is that where Fig.8 shows the kind of result I was getting using the laptop, dongle and mini-whip in the office, the opener shows the kind of result with everything out in the backyard and the mini-whip on the top of the rotary clothesline centre pipe. (And you thought that rotary clotheslines were only for kids to swing on . . .) As you can see there are more aircraft visible in the ‘outside’ configuration, but not dramatically so. The other thing to note is that the results with the miniwhip antenna are pretty much as good as you’d expect with any antenna. So depending on your location, this kind of el-cheapo antenna might be all you need for ADSB reception too. So that’s ADS-B – your choice as to whether you view it via the internet or view the actual transmissions from ’planes in your area. SC siliconchip.com.au