RE: [Discuss-gnuradio] Decimate by 2 possible?

[Nirali Patel]

Brian,

Thanks for your response. 

> What is your target symbol rate?  

My target symbol rate is 10.76 MHZ (8-vsb ATSC symbol rate). I need only 2x
of this symbol rate, i.e 21.52 Mhz to do down stream processing. 

>Is there a reason you want to play directly with 32Msps?  
Only for troubleshooting interpolation-algorithm problems on the downstream
board. 
If I send a lower rate e.g 8Msps then there is a need for interpolation
first and it appears that there is a bug in the algorithm for cubic
interpolation method on the downstream board that causes sampling offsets.
So it would be nice if there was only downsampling involved in getting to
21.52 Mhz. 
 
> Maybe it would be better if you decimated to 1x or 2x the symbol rate
> and then processed that data on your other board?
Yes, you are right. Ultimately I should only send the decimated data.
If I use both the CIC and HBF then the lowest combined decimation rate is 8,
which gives me 8 Msps output. I might avoid the HBF for now and get a
decimation of 4 in the CIC. I found from an earlier post that the file
4rx_0tx.rbf has only CIC and no HBF. Do you know how this file can be
generated? I need to start at the toplevel in order to make connections to
the debug IO pins. 

> What do you think?  Is this more plausible of a scenario for you?
This definitely makes good sense. Thanks for the suggestions!

Nirali Patel