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authorMatthias P. Braendli <matthias.braendli@mpb.li>2018-01-24 06:15:51 +0100
committerMatthias P. Braendli <matthias.braendli@mpb.li>2018-01-24 06:15:51 +0100
commit01aae2e6e9e2b9f3c354ccff62cfba1f79f20f73 (patch)
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parentfb14b0eaf4cc8211b529724e521150643fee2064 (diff)
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Say something about the Ettus GPSDO
Diffstat (limited to 'sfn.tex')
-rw-r--r--sfn.tex23
1 files changed, 17 insertions, 6 deletions
diff --git a/sfn.tex b/sfn.tex
index 87e71e2..8b243c3 100644
--- a/sfn.tex
+++ b/sfn.tex
@@ -123,7 +123,7 @@ t_{transmission} = t_{TIST} + \delta
If this offset is set to a higher value, there will be a bigger delay (measured
in absolute time) between the point in time a frame is multiplexed and the point
in time the frame is transmitted. More frames therefore will be buffered in
-the ODR-DabMod ZeroMQ input, increasing robustness against network latency
+the ODR-DabMod input, increasing robustness against network latency
fluctuations.
The offset already has two functions: it compensates for network delay and
@@ -137,10 +137,11 @@ therefore rewrite the above equation as:
t_{transmission} = t_{TIST} + \delta_{network} + \delta_{planning}
\]
\[
- \delta = \delta_{network} + \delta_{planning}
+ \delta_{offset} = \delta_{network} + \delta_{planning}
\]
-\sidenote{Explain relationship with ZeroMQ max buffer size}
+When using the ZeroMQ input, the \verb+max_frames_queued+ setting must be
+large enough to contain enough ETI frames to accommodate the offset.
\subsection{Using ODR LEA-M8F GPSDO board}
@@ -166,8 +167,9 @@ that the GPSDO is locked properly, and different configuration settings for the
clock management PLL inside the USRP, making the USRP compatible to the
$30.72$MHz reference clock frequency.
-The modified UHD version is available at
-\url{http://www.github.com/Opendigitalradio/uhd.git} and replaces Ettus' UHD.
+The modified UHD version is available on the ODR GitHub\footnote{
+ \url{http://www.github.com/Opendigitalradio/uhd.git}} and is used in place
+of Ettus' UHD.
ODR-DabMod can be configured as follows:
\begin{lstlisting}
@@ -180,7 +182,16 @@ max_gps_holdover_time=600
\subsection{Using Ettus GPSDO}
+When using the GPSDO from Ettus, which is a Jackson Labs Firefly module, no
+special UHD version needs to be installed.
-\sidenote{Give example}
+The configuration is:
+\begin{lstlisting}
+[uhdoutput]
+refclk_source=gpsdo-ettus
+pps_source=gpsdo
+behaviour_refclk_lock_lost=crash
+max_gps_holdover_time=600
+\end{lstlisting}
% vim: spl=en spell tw=80 et