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guides:sdr_tracker [2013/03/14 13:09] – Updated - needs screen shots amending will do that tonight upuguides:sdr_tracker [2018/08/21 12:57] (current) – [Decoding the Payload] kevwal
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 The RTL2832U outputs 8-bit I/Q-samples, and the highest theoretically possible sample-rate is 3.2 MS/s, however, the highest sample-rate without lost samples that has been tested so far is 2.8 MS/s. The frequency range is highly dependent of the used tuner, dongles that use the Elonics E4000 offer the widest possible range (64 - 1700 MHz with a gap from approx. 1100 - 1250 MHz). The RTL2832U outputs 8-bit I/Q-samples, and the highest theoretically possible sample-rate is 3.2 MS/s, however, the highest sample-rate without lost samples that has been tested so far is 2.8 MS/s. The frequency range is highly dependent of the used tuner, dongles that use the Elonics E4000 offer the widest possible range (64 - 1700 MHz with a gap from approx. 1100 - 1250 MHz).
 +
 +WARNING : It is unlikely you will be able to use these devices for tracking a real flight unless you have a very good antenna. However for bench testing payloads they are more than adequate.
 +
 +===== Note on Antennas =====
 +
 +For testing all that is really needed is a piece of wire 164mm (1/4 the wave length of a 434Mhz signal) pushed in the end of the dongle. A small 433/434Mhz stub antenna screwed in the end will also suffice. Neither of these will allow you to track real flights unless they are extremely close. 
 +
  
 ===== Compatible Devices ===== ===== Compatible Devices =====
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 Data sourced from http://sdr.osmocom.org/trac/wiki/rtl-sdr. The E4000 is hard to get hold of these days to the one you should be going for are R820T based boards. Some of the earlier boards lacked the anti static protection to allow the use of these with larger antennas.  Data sourced from http://sdr.osmocom.org/trac/wiki/rtl-sdr. The E4000 is hard to get hold of these days to the one you should be going for are R820T based boards. Some of the earlier boards lacked the anti static protection to allow the use of these with larger antennas. 
  
 +**Warning. I don't know if mine is broken but its totally useless at receiving actual in the air HABs. Ok for testing but it drifts badly too. I would appreciate anyone else who has uses these giving some feed back thanks - Upu**
 The [[https://www.cosycave.co.uk/product.php?id_product=288|NEWSKY TV28T RTL 2832U / R820T]] is a extremely cost effective unit that comes with an SMA adaptor.  The [[https://www.cosycave.co.uk/product.php?id_product=288|NEWSKY TV28T RTL 2832U / R820T]] is a extremely cost effective unit that comes with an SMA adaptor. 
 +Older versions of TV Dongles do drift however more recent (2015) versions are much better and are used by many people for tracking.  Dedicated dongles such as Airspy are now much more common and form the basis of very good receivers.
  
 ===== Mac Software  ===== ===== Mac Software  =====
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 The guys at SDRSharp have done a very easy script for installing the dongle. Go to : The guys at SDRSharp have done a very easy script for installing the dongle. Go to :
  
-http://sdrsharp.com/downloads/sdr-install.zip+http://airspy.com/download/
  
 Extract this zip and double click Install. This will create a sub directory called sdrsharp. Within this sub directory double click zadig.exe and you will see the following with an empty list : Extract this zip and double click Install. This will create a sub directory called sdrsharp. Within this sub directory double click zadig.exe and you will see the following with an empty list :
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 Run sdrsharp.exe and you will see the following window: Run sdrsharp.exe and you will see the following window:
  
-{{:guides:sdr_1.png|}}+{{:guides:sdr1.png|}}
  
 Check WFM \\  Check WFM \\ 
-Next to front end drop the box down and select RTL-SDR / RTL2832U\\  +Next to the PLAY button drop the box down and select RTL-SDR / USB\\  
-Next to center type 98,000,000 (enter)\\ +Amend the VFO Frequency to 98,000,000 \\ 
 Press Play\\  Press Play\\ 
  
-{{:guides:sdr_2.png|}}+{{:guides:sdr2.png|}} 
 + 
 +If you have it selected correctly you will see something like the following. Each of those large peaks on the waterfall are commercial FM radio stations. Put your red cursor over one and click. You should be able to hear the station.  
 + 
 +The big spike that's always present in the middle is the [[http://en.wikipedia.org/wiki/DC_bias|DC Offset]] and can be ignored. 
  
-If you have it selected correctly you will see something like the following. Each of those yellow and red lines on the waterfall are commercial FM radio stations. Put your red cursor over one and click. You should be able to hear the station.  
 ===== Listening for a Payload ===== ===== Listening for a Payload =====
  
-Due to the huge bandwidth of the dongles you can seem pretty much the whole frequency range the payloads operate on in one fell swoop, however sometimes this does make locating the payloads in all the noise difficult.Amend the centre frequency of the dongle to 434,500,000 and the mode to USB.+Due to the huge bandwidth of the dongles you can seem pretty much the whole frequency range the payloads operate on in one fell swoop, however sometimes this does make locating the payloads in all the noise difficult.Amend the VFO frequency of the dongle to 434,500,000 and the mode to USB.
  
 You should now see something like this : You should now see something like this :
  
-{{:guides:sdr_3_-_copy.png|}}+{{:guides:sdr3.png|}}
  
 Now turn your payload on. You should see a spike around the frequency of your payload : Now turn your payload on. You should see a spike around the frequency of your payload :
  
-{{:guides:sdr_4_-_copy.png|}}+{{:guides:sdr4.png|}}
  
-Click near to this with your cursor, then zoom in slightly, the reposition your cursor over the top of the peak (in this example I've increased the filter bandwidth to 4000 as well) :+Click near to this with your cursor, then zoom in slightly, the reposition your cursor over the top of the peak  :
  
-{{:guides:sdr_5.png|}}+{{:guides:sdr5.png|}}
  
-At this point you should be hearing the RTTY from your payload. You can zoom in / amend filter bandwidth to get it spot on the frequency. You can expand FFT Display and increase the resolution to make the waterfall and spectrum analyser less blocky.+At this point you should be hearing the RTTY from your payload. You can zoom in / amend filter bandwidth to get it spot on the frequency. You can increase the resolution to make the waterfall and spectrum analyser less blocky.
  
 ===== Decoding the Payload ===== ===== Decoding the Payload =====
  
 For the next step you will need to download and install Virtual Audio Cable or some other such software.  For the next step you will need to download and install Virtual Audio Cable or some other such software. 
 +
 +Some sound cards under Windows support "Stereo mix" which is a built in feature to perform this function for you. Enable it following these instructions: http://www.howtogeek.com/howto/39532/how-to-enable-stereo-mix-in-windows-7-to-record-audio/
 +
 +If not, chose one of the below pieces of software.
  
 Virtual Audio Cable is available here : http://software.muzychenko.net/eng/vac.htm Virtual Audio Cable is available here : http://software.muzychenko.net/eng/vac.htm
 +Virtual Audio Cable demo send some voice over the channel saying "TRIAL" so it's pretty useless now for this use.
 +
 +VB-CABLE Driver: http://vb-audio.pagesperso-orange.fr/Cable/index.htm, (21/08/18 Now moved to here: https://www.vb-audio.com/Cable/index.htm). VB-Cable driver is a donationware. The configuration steps are the same than VAC. You should try this one.
  
 Jack Audio is availble here : http://www.jackaudio.org/ Jack Audio is availble here : http://www.jackaudio.org/
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 You should now be able to click on the payload as normal and decode : You should now be able to click on the payload as normal and decode :
  
-{{:guides:sdr_7.png|}}+ 
 +{{:guides:sdr6.png|}}
  
  
guides/sdr_tracker.1363266579.txt.gz · Last modified: 2013/03/14 13:09 by upu
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