Technical Manual

ATLAS 4500 Multimode Station Technical Manual December 2016 A-13
Controller Board Appendix A - UHF Circuit Descriptions
• I2C bus for exciter serial flash and FPGA ARM communication from the
Controller
• TXVCO volts monitor line. Exciter PTT line from the Controller,
• The main data stream using 3 x I2S data communication lines from DSP, 2 Serial
data lines from the Controller board for diagnostic use.
• 1 pps line to FPGA for similcast.
• FPGA PTT, FPGA TP G line, FPGA TP H line (initially used).
• The Controller can sense the presence of external 10 MHz reference
(>approximately0 dBm 0.5 Vpp) using Ex ref line. The Controller can select
External reference using Ext osc sw line. This is done by software control to
allow correct handover.
A.4.2.3 RX Interface
There are RX interfaces for 2 receivers. This allows a second diversity RX option.
The RX connector is a 30-pin connector. Most lines are common for both. This
includes 12-V and 3.3-V supplies, I2C bus for the serial flash used for synthesizer
band selection and PLL gain.
The Controller sets the channel frequency through the common PLLDAT and
PLLCLK and RX1 EN and RX2 EN lines. Each of the 2 VCO bands is selected by
means of 2 VCO band lines. Each RX VCO control voltage can be monitored on
each RX1VCO and RX2VCO line.
A.4.2.4 DSP Interface
The DSP overall controls the base station.
The DSP control serial data (RS232) communication is sent to the Controller using
a protocol. This controls modulation mode, channel frequency, power etc. The
Controller then sends I2C to the Exciter and logic for PTT, sets PA power etc.
The DSP TX modulation data is sent synchronously through the I2SCLK, I2SDAT,
ISFRM lines to the Exciter FPGA. The FPGA controls the clock and frame timing
of this interface, where DSP provides raw data. A 1-pps signal from the DSP can be
provided for precise simulcast timing.
The DSP RX IF comes from the RX to DSP. The main RX1 and optional RX2 90
MHz IF signals are fed directly from the receivers to the DSP section RX sub board
through coax cables from CN2.