Difference between revisions of "Pulsar radiowave reception"

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(Modelling a yagi antenna)
 
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== Goal of a project ==
 
== Goal of a project ==
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 +
== Pulsar frequencies ==
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According to [http://www.jb.man.ac.uk/distance/frontiers/pulsars/section4.html] the strongest signals received from pulsars are around 400 MHz which is close to 70 cm radioamateur band.
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They have wider spectrum and can be received at higher frequencies just the signal will be weaker.
  
 
== Modelling a yagi antenna ==
 
== Modelling a yagi antenna ==
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=== Antenna materials ===
 
=== Antenna materials ===
  
== radio equipment setup ==
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== Radio equipment setup ==
=== schematic block ===
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=== Schematic block ===
 
=== Filtering out frontend overload from unwanted radio stations ===
 
=== Filtering out frontend overload from unwanted radio stations ===
 +
We have access to a crystal 70cm bandpass 430-440MHz Filter, that can attenuate FM stations a bit.
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Without this filter, there is a problem with reception of weak signals using any software defined radio.
 +
If any problem arises, coax notch bandstop filters can be used to attenuate nearby problematic radio stations.
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After all passive filtering, signal from antenna can be amplified using cca 20dB LNA modules from china.
  
== software setup ==
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== Software setup ==
=== searching for signal buried in noise ===
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=== Searching for signal buried in noise ===
 
According to reception by G0JLO, signal needs to be integrated for 2 to 3 hours to be recognisable in radiowave noise background [http://www.neutronstar.joataman.net/sites/g0jlo/index.html]
 
According to reception by G0JLO, signal needs to be integrated for 2 to 3 hours to be recognisable in radiowave noise background [http://www.neutronstar.joataman.net/sites/g0jlo/index.html]

Latest revision as of 01:08, 16 January 2020


Goal of a project

Pulsar frequencies

According to [1] the strongest signals received from pulsars are around 400 MHz which is close to 70 cm radioamateur band. They have wider spectrum and can be received at higher frequencies just the signal will be weaker.

Modelling a yagi antenna

This is an antenna we want to build but we don't have dimensions: [2] The boom yagi antenna has 43 elements and is 12m long. We want the antenna to be portable with a ladder rope structure, that can be hanged on a tree.

Next, this is an antenna with model, nice characteristics and known dimensions: [3]

There was a problem with characteristics from 4nec2 model after calculating the 43 element antenna. The characteristics chart did show, that gain was inconsistent just by changing angle a little, there was no smoothness in a beam facing to the front of an antenna. Problematic modeled design: [4]

Software to calculate the antenna: [5]

Online yagi antenna calculator: [6]

Building an antenna

Antenna materials

Radio equipment setup

Schematic block

Filtering out frontend overload from unwanted radio stations

We have access to a crystal 70cm bandpass 430-440MHz Filter, that can attenuate FM stations a bit. Without this filter, there is a problem with reception of weak signals using any software defined radio. If any problem arises, coax notch bandstop filters can be used to attenuate nearby problematic radio stations. After all passive filtering, signal from antenna can be amplified using cca 20dB LNA modules from china.

Software setup

Searching for signal buried in noise

According to reception by G0JLO, signal needs to be integrated for 2 to 3 hours to be recognisable in radiowave noise background [7]