Doppler correction, SatCom channel.

Hi,

I am looking at a Goldcode transmitted from a LEO satellite and want to perform a matched filter on it. The problem is there is a significant amount of doppler (20kHz) which degrades the performance of the matched filter significantly.

If I have a chunk of this signal (quadrature sampled) what would be a good approach to negate the affects of the doppler?

Any input will be much appreciated. Thanks.

ZZ

On Tuesday, February 20, 2018 at 10:22:31 AM UTC-5, Zoul Zubazz wrote:
> Hi,
> 
> I am looking at a Goldcode transmitted from a LEO satellite and want to perform a matched filter on it. The problem is there is a significant amount of doppler (20kHz) which degrades the performance of the matched filter significantly.
> 
> If I have a chunk of this signal (quadrature sampled) what would be a good approach to negate the affects of the doppler?
> 
> Any input will be much appreciated. Thanks.
> 
> ZZ

This might be a dumb question, but don't you have a way of getting the LEO's orbit parameters?

On Tuesday, February 20, 2018 at 10:22:31 AM UTC-5, Zoul Zubazz wrote:

> I am looking at a Goldcode transmitted from a LEO satellite and want
> to perform a matched filter on it. The problem is there is a significant
> amount of doppler (20kHz) which degrades the performance of the matched
> filter significantly.

> If I have a chunk of this signal (quadrature sampled) what would be a
> good approach to negate the affects of the doppler?

You can try a suitably large set of possible doppler values and see which
one best allows extraction of the signal.

(Yes, it is sometimes done this way.)

Steve

On 21.02.2018 7:27, Steve Pope wrote:
> On Tuesday, February 20, 2018 at 10:22:31 AM UTC-5, Zoul Zubazz wrote:
>
>> I am looking at a Goldcode transmitted from a LEO satellite and want
>> to perform a matched filter on it. The problem is there is a significant
>> amount of doppler (20kHz) which degrades the performance of the matched
>> filter significantly.
>
>> If I have a chunk of this signal (quadrature sampled) what would be a
>> good approach to negate the affects of the doppler?
>
> You can try a suitably large set of possible doppler values and see which
> one best allows extraction of the signal.
>
> (Yes, it is sometimes done this way.)
>
> Steve
>

You might want to read Chapter 5 of Kaplan's "Understanding GPS" -- 
"Satellite signal acquisition, tracking and data demodulation".

It might be useful or not, depending on the specifics.

Gene.