Re: [Discuss-gnuradio] Find and look to center frequency and phase of bandwidth with help of stored original version of that

[Cinaed Simson]

Maybe use TDMA - multiple time slots.

-- Cinaed



On 08/21/2017 05:52 AM, mohammad nejati wrote:
> 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 :
> http://www.newtec.eu/frontend/files/leaflet/bwc0900-bandwidth-canceller.pdf
> 
> 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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