Theory Of Operation; General Information; Unit Description; Front Panel - Aeroflex NAV 2000R Operation Manual

4.1

GENERAL INFORMATION

The NAV 2000R Theory of Operation is contained in this Section. The General Description section
describes the function of the various parts of the hardware. The Functional Description discusses the
output parameters of the NAV 2000R. The Software section covers the software with respect to how it
affects the hardware.
4.2

UNIT DESCRIPTION

The NAV 2000R has three major sections; the front panel, rear panel and chassis. The front panel
includes the keypads, power switch and display and is used for local operation. The chassis section
includes the housing, power supply, and line power connection. Within the housing is a card cage which
contains the motherboard and slots for the system computer (CPU) board, DSP board, and AM Modulator
Module. The synthesizer module is mounted next to the card cage.

4.2.1 FRONT PANEL

The front panel contains the flat panel electro-luminescent display, the ON/OFF power switch, the mode
select keypad, the cursor control and select keypad, "hot" key keypad, and the numeric keypad. Each of
the keypads are part of one keyboard. The display horizontal sync, vertical sync, clock, and display data
are routed to the display through the keypad board.
The keypads are mapped into two banks. When a key is depressed (after debouncing), its row and
column are latched on the keypad board. Additionally, the row and column is decoded to determine
whether the depressed key is from the upper or lower bank. This bank decoding actually forms part of
the address which the system processor uses to access the latches which indicate row and column.
The display is driven by the system computer board. The video dynamic RAM is written to the display on
a refresh basis. To refresh the display, a DMA of the contents of the video RAM to a parallel to serial
interface is done every horizontal sync period. The parallel to serial interface converts the dynamic video
RAM contents to a two byte row and column address. Although the write to the interface is on one write
cycle, the write to the display is actually on two write cycles; one for the row and one for the column. The
data is then applied to a parallel to serial converter and, along with the generated clock and horizontal
and vertical syncs, is routed through the keypad board to the display.

4.2.2 REAR PANEL

The rear panel provides access to the card cage modules, the power connector, fuse holder and the
synthesizer module. The system computer board, DSP board, and AM module are removable from the
rear panel. The system computer board provides an IEEE-488 interface connector. The external mod
audio input, RF input, and RF output are provided as part of the AM modulator. An audio output is
provided as part of the DSP board. Time base input and output are provided as part of the synthesizer
module.
NAV 2000R SIGNAL GENERATOR - REV. 0 – JULY 26, 2007 - PG 4-1
Aeroflex Operation Manual
SECTION IV

THEORY OF OPERATION