From 4042a319fd29bd5be7b28ce7d3383a2eccaeb7b8 Mon Sep 17 00:00:00 2001 From: Michael West Date: Mon, 7 Oct 2019 16:41:15 -0700 Subject: N3xx: Remove close-in noise on TX Some close-in noise was observed on TX when using external references. This change reduces the noise by changing U19 to select the GPSDO when references are set to external. Also included is a change to properly read and apply settings from the configuration file. This allows the user to further quiet the transmission by adding 'enable_gps=False' to the configuration file in order to power off the GPSDO. Signed-off-by: Michael West --- host/docs/usrp_n3xx.dox | 3 +++ 1 file changed, 3 insertions(+) (limited to 'host/docs') diff --git a/host/docs/usrp_n3xx.dox b/host/docs/usrp_n3xx.dox index 052f20ee9..18a8a023b 100644 --- a/host/docs/usrp_n3xx.dox +++ b/host/docs/usrp_n3xx.dox @@ -664,6 +664,9 @@ and time. auto usrp = uhd::usrp::multi_usrp::make( "type=n3xx,clock_source=external,time_source=external"); ``` +To reduce phase noise, it may be necessary to power down the GPSDO when using +an external reference. To do this, just add `enable_gps=False` to the +configuration file in `/etc/uhd/mpm.conf` (see also \ref page_configfiles). Note: When disabling the GPS with `enable_gps=0` in the configuration file, or -- cgit v1.2.3