Nav 2000R Software - Aeroflex NAV 2000R Operation Manual

The selected output, direct, divided by two, or divided by four, is passed through an appropriate low pass
filter to reduce harmonics. There are two filters per octave. The approximate corner frequencies of each
filter and the output frequency range passed by each is listed below. For output frequencies of 56.25 to
75.5 MHz a 90 MHz LP is selected. For output frequencies of 75.5 to 112.5 MHz, a 130 MHz LP is
selected. For output frequencies of 112.5 to 155 MHz, a 180 MHz LP is selected. For output frequencies
of 155 to 225 MHz, a 260 MHz LP is selected. For output frequencies of 225 to 310 MHz, a 375 MHz LP
is selected. For output frequencies of 310 to 450 MHz, a through path is selected.
The 400 MHz Loop is used to generate a 400 MHz LO signal for the Low Band Mixer. Applied to this
loop phase detector, are the 10 MHz reference from the REF/CONTROL board and the output of a divide
by 40 RF prescaler. The output of the phase detector is low pass filtered and applied to the tuning line of
the 400 MHz VCO.
The output of the 400 MHz VCO is buffered and applied as the LO of the balanced Low Band Mixer at a
level of 7 dBm. The Main VCO output is padded down and applied to the Mixer RF input. The IF output
of the Mixer is filtered by a 68 MHz low pass filter and amplified. The resulting output is the Low Band
frequency of between 150 kHz and 56.25 MHz.
The 400 MHz VCO may be switched on or off. This VCO operates only during Low Band frequency
generation.
The Main VCO is actually four VCO's, each covering only a part of the Main VCO frequency range. The
output of each VCO is combined, buffered, and split. Only one of the four VCOs operate at one time.
The outputs are split three ways; to the PLL buffer and two, to an output buffer.
All of the possible outputs are combined and then passed through a 500 MHz LP filter. Following this
filter is the leveling loop. The leveling loop is composed of a voltage controlled attenuator, an Amplifier,
and a diode detector and error amp. This loop maintains the output level of the synthesizer at -20 dBm.
4.3.14 REVERSE POWER PROTECTION MODULE
(-50 units with Mod Status 7 only)
The Reverse Power Protection (RPP) module provides a mean for interruption of the RF path between
the unit under test (UTT) and NAV 2000R output. Should a high RF signal be fed to the NAV 2000R
output connector, while testing a transceiver for instance, an internal switch in series with the RF output
will open. In addition to RF protection, the RPP module also contains a DC block, which will prevent
damage to the output stage if connected to a circuit operating at a DC potential.

4.4 NAV 2000R SOFTWARE

Following is a short description of the NAV 2000R basic operating software. The software versions are
displayed upon power up.
The operation software of the NAV 2000R resides on the system computer board. This software controls
all other boards and modules within the NAV 2000R. The display characters and fields are defined by the
software, which writes the display information into Video Ram. Hardware, under software control within
the system computer board, outputs the contents of Video Ram to the display. The keyboard interrupts
the main program. Interrupt handling routines receive and pass the key value to the main program. The
main program processes the new information. Interrupts from the GPIB bus are handled similarly.
NAV 2000R SIGNAL GENERATOR - REV. 0 – JULY 26, 2007 - PG 4-11
Aeroflex Operation Manual