usrp2: added app notes on multi channel RX

1 files changed, 17 insertions, 0 deletions

diff --git a/host/docs/usrp2.rst b/host/docs/usrp2.rst
index 2eb3ee796..904005ce0 100644
--- a/host/docs/usrp2.rst
+++ b/host/docs/usrp2.rst
@@ -393,3 +393,20 @@ they can be queried through the API.
 * mimo_locked - clock reference locked over the MIMO cable
 * ref_locked - clock reference locked (internal/external)
 * gps_time - GPS seconds (available when GPSDO installed)
+
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Multiple RX channels
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+There are two complete DDC chains in the FPGA.
+In the single channel case, only one chain is ever used.
+To receive from both channels,
+the user must set the RX subdevice specification.
+This hardware has only one daughterboard slot,
+which has been aptly named slot "0".
+
+In the following example, a TVRX2 is installed.
+Channel 0 is sourced from subdevice RX1,
+channel 1 is sourced from subdevice RX2:
+::
+
+    usrp->set_rx_subdev_spec("0:RX1 0:RX2");