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LOCAL OSSILATOR - drop of data with sytnhesizer

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romiyo123

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LOCAL OSSILATOR

Hi ,

Here is my situation.

In my system if I used my synthesizer I can see drop data.If I replace synthesizer with signal generator I can not see any data drop.

Is there a possiblity that LO loose it syncronization?

Some power line at 220V AC is in same area as power line for synthesizer. Is this create a problem?
 

vfone

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Re: LOCAL OSSILATOR

Not only frequency instability (or PLL un-lock) affects the data transmission.

In data transmissions using modulations as QPSK, QAM, OFDM, etc, also the Phase Noise of the LO could affect the throughput of the data.
 

romiyo123

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Re: LOCAL OSSILATOR

vfone said:
Not only frequency instability (or PLL un-lock) affects the data transmission.

In data transmissions using modulations as QPSK, QAM, OFDM, etc, also the Phase Noise of the LO could affect the throughput of the data.



Thanks for your reply but I think modulation scheme should be a problema as I just replaced my synthesizer with signal generator . modulation scheme was same for both texperienments.

I am not sure about Phase noise that affects me because I already measure phase noise and itwas good though.
 

Element_115

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Re: LOCAL OSSILATOR

romiyo123 said:
vfone said:
Not only frequency instability (or PLL un-lock) affects the data transmission.

In data transmissions using modulations as QPSK, QAM, OFDM, etc, also the Phase Noise of the LO could affect the throughput of the data.



Thanks for your reply but I think modulation scheme should be a problema as I just replaced my synthesizer with signal generator . modulation scheme was same for both texperienments.

I am not sure about Phase noise that affects me because I already measure phase noise and itwas good though.
VFone was not saying you have a Mod problem,just that some modulation schemes
are impacted more by phase noise.

One thing you can do (if possible) is look at your LO on a Spectrum Analyzer,
make the Span = 50kHz and press the Max Hold option. If your LO moves
a lot then it's your LO stability. Then do the same for the sig-gen see what's the
difference and then fix it.
Cheers
 

saulbit

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I think maybe your impedance match is poor, and you can simply adds a 51 Ohm resistor as a parallel part.
 

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