[hpsdr] Xilinx Coregen DDS

[Robert McGwier]

ABSOLUTELY.   The halfband will give a much flatter response than the 
CIC and it just plain works.  GnuRadio code is there for the stealing.  
Steal it with everyone's GPL blessing.

Bob





Eric Blossom wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> On Thu, Jun 15, 2006 at 09:32:07AM +0800, pvharman at arach.net.au wrote:
>   
>> Hi Eric,
>>
>> No offense taken :).
>>
>> In fact Bill KD5TFD and I had exactly this discussion recently. At the moment 
>> I'm very much in the 'cobble it together as quickly as possible to see if it 
>> works' phase.  As such I tend to use all and any short cuts available. As an 
>> example I'm using MatLab to develop the Verilog code for the CIC filter used 
>> in Mercury. Also Phil C has written a very nice CORDIC NCO based on the USDR 
>> open source code to allow me to get signals from the LT2208 into PowerSDR. 
>>     
>
> Understood.
>
> FYI, there's an implementation of a 31-tap halfband that executes in
> 8-cycles using a single multiplier in the USRP fpga code.
> See usrp/fpga/sdr_lib/hb/halfband_decim.v
>
> There's also code for a 4th order CIC with a maximum decimation factor
> of 256.  We've been down this path before, and use this code every day ;) 
>
> Eric
> K7GNU
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>   


-- 
AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman
Laziness is the number one inspiration for ingenuity.  Guilty as charged!


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