THE REASON OF AN IMPORTANT STRATEGICAL CHOICE

 

THE REASON OF AN IMPORTANT STRATEGICAL CHOICE

 

While I am fond for the excellence of the measuring systems , after long  thinking,  I have recently decided to push on the use of some and cheap tools as an alternative way to make our daily work .

What changed my idea was mainly some things :

- Covid limitation to bring big strange tools , like intruments on airplanes

- Starting to give some intermediate tools to people that doesn’t have any professional instruments

- Advantage that they can start practically to play with something  that we teach on our training at a very low cost

Nevertheless , I have to stress that this is only an intermediate step to professional instruments that luckily in this year cost one tens of the same instruments of let’s say 10 years ago and have same or better performances .

There are NO MIRACLES  : performances are always related to costs .

But at the end I have decided to put together small boxes that , with a PC that you own ,and you always have to bring with you and you are allowed to bring  on an airplane , could help in many cases .

The first small box is a so called RTL USB KEY ( or DONGLE ) .




It is a very small SDR ( Software Defined Radio ) , that connected   to a PC trough an USB 2.0 ( or higher ) port ,and software can allow spectral analysis , demodulation and other measurements from 25 to 1760 MHz .

In this respect I have produced already some video showing how we can point for instance our satellite dishes , or check on air the FM band or a signal from an STL .

The software HDSDR that I have choose for this purpose can be downloaded from here :

https://www.hdsdr.de/

The ExtIO.dll file to use the RTL Dongle , by put it into del HDSDR folder can be downloaded here :

http://hdsdr.de/download/ExtIO/ExtIO_RTL2832.dll

Here you have the links :

Pointing a satellite dish with the use of an RTL USB key  with the software HDSDR

https://www.youtube.com/watch?v=oo-jXJY2zfE

Using an RTL USB Key in the FM BAND with the software  HDSDR

https://www.youtube.com/watch?v=xYK_e_iaJDA

 RTL SDR USB KEY  FOR SAT BEACON MEASUREMENTS with the software HDSDR

https://youtu.be/XtG-YFIKks4

 

Of course there are big limitations due to the Range of Visualization  that an RTL KEY ( that works with 8 bit ) can handle ( around 40dB) respect a professional  Spectrum Analyzer ( 100dB) and also the RTL KEY receive spurious signals and images .

See for instance signals displayed  with a range of 100dB and the range of 40 dB in evidence .



 

The reason why 8 bit correspond to around  40dB can be found here :

https://fte.com/WebHelpII/AES/Content/Documentation/AudioExpertSystemReferenceGuide/PrecisionAndDynamicRange.htm 

where this picture was extracted :


Claudio Re

 

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