Installation Instructions

Hardware Installation
RVP8 User’s Manual
September 2005
2–38
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Command | Data | CMD/DATA
|_______________|_______________________________________________|
Commands #1, #2, and #3 control the 25 output pin levels of the DAFC board. These
transmissions may be interspersed with the PLL-16 format in systems that require both clock
locking and AFC, e.g., a dual-receiver magnetron system using a digitally synthesized COHO.
Note that the entire 25-bits of pin information are transferred synchronously to the output pins
only when CMD=3 is received. This assures that momentary invalid patterns will not be
produced upon arrival of CMD=1 or CMD=2 when the output bits are changing.
CMD=1 Data<0> DAFC output pin 25
Data<6> Fault Input is active high
Data<11:7> Which pin to use for Fault Input (0:None)
CMD=2 Data<11:0> DAFC output pins 24 through 13
CMD=3 Data<11:0> DAFC output pins 12 through 1
These three digital AFC pinmap commands are recommended as a replacement for the original
AFC-16 format in all new hardware designs. If you only need 12-bits of linear AFC, then map
the AFC range into the –2048 to +2047 numeric span, and select binary coding format (See
Section 3.2.6); the 12-bit data with CMD=3 will then hold the required values. To get a full
16-bit value, use a –32768 to +32767 span and extract the full word from both CMD=2 and
CMD=3. Of course, other combinations of bit formats and number of bits (up to 25) are also
possible.
Command #4 is used to control some of the internal features of the IFD. Bits <4:0> configure
the on-board noise generator so that it adds a selectable amount of dither power to the A/D
converters. This noise is bandlimited using a 10-pole lowpass filter so that most of the energy is
within the 150KHz to 900KHz band, with negligible residual power above 1.4MHz. Each of the
five bits switch in additional noise power when they are set, with the upper bits making
successively greater contributions. Bits <6:5> permit the IF-Input and Burst-Input signals to be
reassigned on the downlink.
CMD=4 Data<4:0> Built-in noise generator level
IF-Input and Burst-Input selection
Data<6:5> 00 : Normal 01 : Swap IF/Burst
10 : Burst Always 11 : IF Always
Data<7> 0 : Normal 1: Swap Pri/Sec IF
Data<8> Downlink IF data stream format
0 : Normal 72MHz single channel
1 : Half-band 36MHz dual channel
Data<9> 0 : Low Half-band 1: High Half-band