[SOLVED] QPSK Output Freqency

[rawanayyoub]

Hi all,
Please I need to Know what is the output frequency result from QPSK modulator as in Picture below ????



I mean that the result after the summer amplifier which has inputs : the output of balance modulator in Inphase branch , and the output of balance modulator in Quadrature branch, Thanks for any help.

Thanks in advance,
Rawan Ayyoub

 

[Mityan]

The center will be oscillator frequency, the spectrum width will be from -1/bit duration to +1/bit duration beside the center (carrier).

 

[rawanayyoub]

The center will be oscillator frequency, the spectrum width will be from -1/bit duration to +1/bit duration beside the center (carrier).

Dear Mityan ,
Firstly thanks for replay, but please if you can give more explanation at this point , because I need to know how much exactly frequency to calculate Antenna length , and if you can help me with any books or links to get it clearly for me at this situation, thanks for your time.

Kind regards,
Rawan Ayyoub

 

[Mityan]

Your diagram means that you carry your baseband IQ signal from 0 frequency to oscillator frequency.
Then look for antenna calculations on web.
If you are assigned only one channel in any frequency range (according to any communication standard), then estimations supposed to be easier. If there is a range of channels whose total band exceeds several percent of central frequency, you should provide this for antenna design.
There are a lot of amateur radio antenna types and calculations for the very wide range of frequencies.

 

[rawanayyoub]

Your diagram means that you carry your baseband IQ signal from 0 frequency to oscillator frequency.
Then look for antenna calculations on web.
If you are assigned only one channel in any frequency range (according to any communication standard), then estimations supposed to be easier. If there is a range of channels whose total band exceeds several percent of central frequency, you should provide this for antenna design.
There are a lot of amateur radio antenna types and calculations for the very wide range of frequencies.

Dear Mityan,
Firstly thanks for replay, but I'm asking for the specific output frequency from the summer amplifier to make me have ready to calculate the Antenna length, I can't calculate that without the specific frequency , and I used Isotropic Antenna with small distance. So Only I need how I can calculate the frequency of the signal which out from the summer. Please I need your explanation So badly, And Sorry for bad English.

With My deepest thanks,
Rawan Ayyoub.

 

[Mityan]

You dont know your oscillator frequency and ask me?

 

[rawanayyoub]

You dont know your oscillator frequency and ask me?

Dear Mityan,
I know the oscillator frequency on my system, I Asked to be sure about the frequency, because the signal entered the summer, it was the result from the mixer , finally I asked just to know what is the change resulted from mixing and summing on the frequency ????

Kind regards,
Rawan Ayyoub

 

[Mityan]

Be sure.
Each shoulder of your half-wave antenna must have length c/(4*fosc), where c is speed of light, fosc - oscillator frequency.

 

[Positron89]

Hi, maybe these links may help..

**broken link removed**
http://pdfserv.maximintegrated.com/en/an/AN686.pdf

 

[kripacharya]

Be sure.
Each shoulder of your half-wave antenna must have length c/(4*fosc), where c is speed of light, fosc - oscillator frequency.

usually you would put in a factor of around 0.95 for this calculation, since the EM length is thought to be a little longer than the physical dipole antenna length.

 

[Mityan]

usually you would put in a factor of around 0.95 for this calculation, since the EM length is thought to be a little longer than the physical dipole antenna length.

Yes. The tradeoffs between dipole length/width allows to achieve more or less frequency band at lower costs (i.e. parameters degradation), and the thread author will learn all of this if he tries google.