[USRP-users] DDC's Filters in B210

Derek Kozel derek.kozel at ettus.com
Wed Jul 19 07:28:10 EDT 2017


Hello Altug,

The CIC can be programed to decimate by a range of integer amounts. If the
ratio is 20 (50 MHz sampling rate, 2.5 MHz output rate) then both half
bands will be used (divide by 2*2) and the CIC will decimate by 5. Odd CIC
rates have poor filter roll off compared to even rates.

Derek

On Wed, Jul 19, 2017 at 10:52 AM, altuğ kaya via USRP-users <
usrp-users at lists.ettus.com> wrote:

> Dear Martin,
>
> So, CIC's status is a binary one. For example if the ratio is 3, 3%4 = 3
> and because there is a remainder, the CIC is enabled. If the ratio is 20,
> both half-bands will be enabled and CIC is disabled as 20%4 = 0. Did I
> understand correctly?
>
> Regards,
> Altug
>
> On Tue, Jul 18, 2017 at 5:59 PM, Martin Braun via USRP-users <
> usrp-users at lists.ettus.com> wrote:
>
>> Altuğ,
>>
>> per channel, there's 2 half-bands and 1 CIC. The rule is: We try and
>> enable as many half-bands as possible, the rest is done by CIC. So, any
>> ratio of sample_rate to master_clock_rate that is divisible by 4 has 2
>> half-bands, any other even ratio has 1 half-band, and the remainder is
>> done in the CIC.
>>
>> Cheers,
>> Martin
>>
>> On 07/18/2017 07:55 AM, altuğ kaya via USRP-users wrote:
>> > Hello everyone,
>> >
>> > In B210 there are 2 half-band filters and 4 CIC filters. As far as I
>> > know we can select how many filters we would like to use by tuning the
>> > ratio between sample_rate and master_clock_rate. What is the rule of it?
>> >
>> > I am looking forward to your answer,
>> > Altug Kaya
>> >
>> >
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>> >
>>
>>
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>
>
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