On Wed, Mar 26, 2025 at 10:43 AM Marcus D. Leech <patchvonbr...@gmail.com> wrote:
> On 26/03/2025 06:13, je.amg...@gmail.com wrote: > > > > I'm using timed commands to set the RX gain at a precise moment with > > the following command: > > > > set_command_time(md.time_spec + uhd::time_spec_t(0.02), 0); > > > > However, I noticed that there is a delay between the specified time > > and the actual time when the gain is applied. This delay is > > significantly larger than the component latency responsible for > > changing the gain and appears to depend on the sampling frequency. > > Specifically, the delay is approximately 20 samples. > > > > I’m trying to understand why this delay is much greater than the > > expected component latency and why it scales with the sampling > > frequency. Any insights on this behavior? > > > > Regards. > > Jamaleddine > > > > > A change in signals presented to the head of the DDC chain will take > some number of sample times to propagate through the > finite-length filters in the DDC. They don't (and, indeed, cannot) > have zero group delay. > Hi Marcus, I think that the gain is set from the "radio" block which operates at the master clock rate rather than the downconverted rate. It doesn't make sense to me why the latency of the gain setting would be related to the downconverted sample rate. Rob
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