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Re: [Discuss-gnuradio] USRP Delay Measurements
From: |
Thomas Schmid |
Subject: |
Re: [Discuss-gnuradio] USRP Delay Measurements |
Date: |
Thu, 9 Nov 2006 12:42:19 -0800 |
Hi Eric,
I did some calculations and something doesn't add up. As I mentioned
in my last email, I am using usrp.sink_s. Thus, my samples are real
shorts (16 bit). I verified the buffer size by printing out the buffer
allocation size in gnuradio-core/src/lib/runtime/gr_buffer.cc. The
size is 32KB.
If I am using an interpolation factor of 400, then my sample rate
should be 128M/400=320k and thus the USB speed should be
320k*2B=640kB/s. With this number, the estimated delay for a sample to
pass through the buffer should be 32k/640k=0.05s. The problem is, that
I measure about 28ms. I think I shouldn't complain, since in reality
the system is faster than what I calculated. Though I still would like
to understand what's going on ;)
Thomas