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Re: [Discuss-gnuradio] Find and look to center frequency and phase of ba

From: mohammad nejati
Subject: Re: [Discuss-gnuradio] Find and look to center frequency and phase of bandwidth with help of stored original version of that
Date: Mon, 21 Aug 2017 17:22:49 +0430

Dear Marcus

There are one 5 Mhz modulated bandwidth centered and transmited on
1ghz . in the cable i add 1 Mhz modulated bandwidth centered in the
same occupied bandwidth for example 1ghz or 1.001 ghz or ..
i want do some thing like this in satellites link :

Thank you .

On Sun, Aug 20, 2017 at 8:41 PM, mohammad nejati <address@hidden> wrote:
> Hi ,
> It is difficult to explain what i need but i want to try it .
> I have a single modulated carrier with 5 Mhz bandwidth i send it throw
> cable and receive delayed version of that with a good SNR like 45dB .
> I store i/q sample in last stage of transmitter ,
> In cable i add one 1 Mhz carrier with lower power into exactly 5 mhz
> equipped bandwidth of carrier (1Mhz carrier is hidden in 5 Mhz carrier
> due to lower signal power) .
> what i want to do is in receiver subtract transited signal from
> received signal in a proper delay and phase and recover 1 Mhz carrier
> .
> I use LMS algorithm for adaption and subtraction and that work only
> when received i/q sample have exactly same center frequency with
> stored transmitted i/q sample which in reality with SDR board and zero
> if architecture it is almost impossible . i don't want find center
> frequency of received carrier with method like costas loop , because
> modulated signal may have difference modulation like 64 QAM , 16 QAM ,
> 32APSK , BPSK ... i want find and lock received center frequency and
> phase with help of that i stored a correct version of that before
> transmit .
> i attached an image of subtracted signal and recovered smaller carrier
> (which is in an ideal condition without frequency drift).
> Thank you ,

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