5 files changed, 91 insertions, 0 deletions

diff --git a/host/docs/dboards.dox b/host/docs/dboards.dox
index 5993501c9..0ab5927a6 100644
--- a/host/docs/dboards.dox
+++ b/host/docs/dboards.dox
@@ -370,6 +370,23 @@ Notes:
   reduce the daughterboard clock rate to 20 MHz to achieve phase
   synchronization and best RF performance (see \ref config_devaddr).
 
+\subsection dboards_twinrx TwinRX
+
+Features:
+-  2 super-heterodyne frontends (2 receive, 0 transmit)
+   - Digital IF of +/- 50 MHz
+- Supports sharing one channel's LO to the other or the use of an external LO
+   - Allows multiple channels and daughterboards to be frequency and phase synchronized
+
+Frequency Range: 10 MHz to 6 GHz
+
+Receive Antennas: **RX1** and **RX2**
+
+Receive Gain: 0-93dB
+
+More information:
+\li \subpage page_twinrx
+
 \subsection dboards_tvrx TVRX
 
 The TVRX board has 1 real-mode frontend. It is operated at a low IF.
diff --git a/host/docs/devices.dox b/host/docs/devices.dox
index 3b4f57b76..f17c15b7d 100644
--- a/host/docs/devices.dox
+++ b/host/docs/devices.dox
@@ -45,6 +45,7 @@ unless stated otherwise, they will still work with this version of UHD.
 ## Daughterboards
 
 \li \subpage page_dboards
+\li \subpage page_twinrx
 
 ## OctoClock
 
diff --git a/host/docs/res/TwinRX_Block_Diagram.png b/host/docs/res/TwinRX_Block_Diagram.png
new file mode 100644
index 000000000..365a524e9
--- /dev/null
+++ b/host/docs/res/TwinRX_Block_Diagram.png
diff --git a/host/docs/res/TwinRX_photo.png b/host/docs/res/TwinRX_photo.png
new file mode 100644
index 000000000..f4043b1f9
--- /dev/null
+++ b/host/docs/res/TwinRX_photo.png
diff --git a/host/docs/twinrx.dox b/host/docs/twinrx.dox
new file mode 100644
index 000000000..c85b78b4c
--- /dev/null
+++ b/host/docs/twinrx.dox
@@ -0,0 +1,73 @@
+/*! \page page_twinrx TwinRX Daughterboard
+
+\tableofcontents
+
+\section twinrx_dboards TwinRX Properties
+
+
+The TwinRX is a two-channel superheterodyne receiver designed for high performance spectrum monitoring and direction
+finding applications. The receiver is tunable from 10 MHz - 6 GHz and has 80 MHz of instantaneous bandwidth per
+channel, providing the versatility necessary to analyze a variety of signals in multiple bands of interest. Each
+channel has an independent RF signal chain with preamplifiers, preselectors, and two mixer stages for superior
+selectivity. Users can tune the two channels independently to simultaneously monitor uplink and downlink
+communication with a combined bandwidth of 160 MHz. The ability to share the LO between channels across multiple
+daughterboards enables the phase-aligned operation required to implement scalable multi-channel phased-arrays.
+The receiver is capable of fast frequency hopping to detect frequency agile emitters.
+
+\image html TwinRX_Block_Diagram.png "TwinRX Block Diagram"
+
+\subsection twinrx_frequency_bands Frequency Bands
+
+The receive filter banks uses switches to select between the available filters. These paths are also dependent on the
+antenna switch settings. Incorrectly setting the switches generally results in attenuated input / output power. Receive
+filters are band pass (series high & low pass filters).
+
+Source code related to controlling the filter band and antenna switches resides in twinrx_experts.cpp. Specifically,
+refer to the `twinrx::twinrx_freq_path_expert` class. Generally, these methods set the switches depending on the state
+of the receive streams.
+
+The following sections provide switch setting tables for antenna and filter selection for frontend's receive paths. For
+further details refer to the schematics.
+
+|  Band  |  Range        |
+|--------|---------------|
+| LB1    | 10 - 500 MHz  |
+| LB2    | 500 - 800 MHz |
+| LB3    | 800 - 1.2 GHz |
+| LB4    | 1.2 - 1.8 GHz |
+| HB1    | 1.8 - 3.0 GHz |
+| HB2    | 3.0 - 4.1 GHz |
+| HB3    | 4.1 - 5.1 GHz |
+| HB4    | 5.1 - 6.0 GHz |
+
+\subsection twinrx_lo_sharing Local Oscillator Sharing
+
+The TwinRX has the ability to export the two Local Oscillator (LO) signals from one channel to the companion channel
+on the same daughterboard and/or to one or more other TwinRXs in order to form a phase-synchronous multi-channel
+receiver.
+
+|  Connector  |  Description |  Min     |  Nominal  |  Damage      |
+|-------------|--------------|----------|-----------|--------------|
+|  J1         |  LO2 Export  |  0 dBm   |  3 dBm    |  NA (Output) |
+|  J2         |  LO2 Input   |  0 dBm   |  2 dBm    |  20 dBm      |
+|  J3         |  LO1 Export  |  -12 dBm |  5 dBm    |  NA (Output) |
+|  J4         |  LO1 Input   |  -10 dBm |  -5 dBm   |  10 dBm      |
+
+\subsection twinrx_antenna_routing Antenna Routing
+
+The TwinRX has two external antenna connectors (RX1 and RX2) which can be switched internally to either
+receiver channel. By default RX1 is connected to the first channel and RX2 to the second.
+
+When routing the antennas in any configuration other than the default there are some behavioral changes to be aware of.
+As can be seen in the block diagram above the signal path from each antenna can be switched into a resistive divider
+and then to either or both of the receive channels. If the divider is in use the incoming signal will be slightly
+attenuated when compared to the direct passthrough. If both receive channels are configured to use the same antenna
+the first two amplifiers and are a variable attenuator are shared. The effect of this is that the first channel's gain
+settings for those amplifiers will override the second channel's. If both channels are tuned to the same frequency band
+and at similar gain settings the effect will be minimal, but if the frequency or gain difference is large the resulting
+gain on the second channel could be significantly lower or higher than expected. Additionally the signal path length
+will increase in comparison to the direct antenna mapping so the phase of the received signal will be different
+depending on the antenna mapping.
+
+*/
+// vim:ft=doxygen: