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problem with the spectrum analyser in rotation case

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ings

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Hello,
plz i have an antenna in rotation and i would like to detect the receiveing power of signal in fuction of the rotation angle
the rotation velocity of our transmiiter is very heigh so it is possible to do this with the spectrum analyser and another software like Labview .
thanks in advance
 

volker@muehlhaus

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This should be easy by setting time sweep (zero sweep bandwidth). For linear polarization, you should get something like cos(angle) dependency.
 
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so i can do this withous using labview, i can do that with the spectrum analyser?
 

volker@muehlhaus

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so i can do this withous using labview, i can do that with the spectrum analyser?

Yes. Set the sweep to zero (=constant frequency) and the spectrum analyzer will show the center frequency over time.
 
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and how can i know the value of rotation angle exactly for each power
 
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The spectrum analyzer sweep has to be triggered by an index signal from antenna drive.
 

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Is this for azimuth detection or maximum signal tuning or what?

A scope can easily output X axis linear ramp for limited radial sweep of RSSI signal or a continuous RF 360 deg rotation with a synchronized index as FvM indicated, then fast retrace on scope or analyze with radial encoder to PC input or a sawtooth generator signal to ADC with a tiny deadband between retrace or 360 and 0 deg into ADC synchronized to antenna index.

Depends on results desired ; scope scan or precision digital result. When I did Doppler design, I chose two antenna and fast time interval counter or measure phase.
 

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Can someone plz gives me the step to visualize the power of received sigal in function of rotation angle with the spectrum analyser because it is not clear for me. in my case i ise the spectrum anlyser agilent, and two antennae 2.4GHz.In the statotionnary state the power of received signal is -36dbm using max hold.
thanks in advance
 

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Too many unknowns.
servo motor V control vs rotation position?
SA sweep voltage output range?

I would use a Scope Y axis out selected bytrigger source to adjust Spectrum Analyzer gain and offset to match a servo motor rotary turntable Vcontrol input. Then use DC to create position markers and match with time base voltage on slow sweep of Spectrum Analyzer.

Then tilt antenna with a compass or guage and repeat to get full 180 deg radiation patterns with zero f sweep in time base mode centred on carrier, while capture and dumping data to PC.

- - - Updated - - -

If not a servo motor but just high RPM motor, then slow it down and use PLL to adjust V to match SA frequency e.g. 10 Hz to control RPM 600 and phase with an optical index marker on shaft.

now geterdone
 

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and how can i know the value of rotation angle exactly for each power

Maximum signal when polarization planes are aligned, minimum signal when polarization planes are 90° different.
And the rotation angle should change linearly over time, so this is rather trivial.
 

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i m trying with the sweep and i chosse 10ms but i can't detect the value of the angle and i m not find cos(angle)
 

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Add optical reflector chip and black Sharpy index mark, run at same speed requires servo loop with index sweep pulse from SA.

The best answer depends always on details missing in your question.
Do not repeat questions without details to my questions. Please.

include all model numbers interfaces and your capability.
 

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Quite obviously, the sweep duration should be set equal to the antenna rotation period.
 

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RPM can be any multiple of sweep speed preferably 2x but must be PLL synchronized. Do you know CD4046 chip and any MOSFEt drivers?

What power is used by motor? Model of SA is mandatory.
 

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You don't necessarily need a PLL if you use a sweep trigger. Any industry standard SA should have it.
 

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my antenna is fixed in motor with an auto transformer 50V; it is necessary to use a sensor of position to detect the position of antenna and also find the value of rotation angle because i m sorry i can't understand your response
 

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This should be easy by setting time sweep (zero sweep bandwidth). For linear polarization, you should get something like cos(angle) dependency.

i find the relation betwenn the angle rotation and the time, so when i put the sweep value of the spectrum analyser equal to the antenna rotation period , the spectrum analyser will detect the value of power of signal each the sweep time and store it in spectrum analyser ie. when the sweep time =1s, it will detect the value of receiving power each 1s
 

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it will detect the value of receiving power each 1s

If you set the spectrum analyzer to zero span, it will show a continuous curve of receiving power over time (like oscilloscope).
 
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If you set the spectrum analyzer to zero span, it will show a continuous curve of receiving power over time (like oscilloscope).

it will show the value of receiving power in real time in function of time or in function of frequency
 
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it will show the value of receiving power in real time in function of time or in function of frequency

If you set the span to zero, it will receive at fixed frequency and show results over time.
You can change the time scale by changing the sweep time.
 
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