FireFox Synthesizer User Manual
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© 2006 Jackson-Labs
1.4.10.3 Sys Config
This menu item will show various FireFox system parameters.
The first item in the LCD is the FireFox Signal Generator Firmware version. SCPI commands are
available with Firmware Version 3.0 or later.
The GPS type is displayed. The M12+ or M12M receivers are used in the FireFox Signal Generator.
The MTI OCXO version is displayed in this menu item. The single oven default OCXO is
MTI230-0827. The double oven OCXO option is MTI270-0269
The last display item is DDS Resolution. The DDS resolution is the internal resolution limit due to
the 48 bit DDS setup. The smallest DDS step size is 1.7764microhertz, and the highest step size is
14.2109microhertz, depending on the output frequency. The system will generate an output
frequency closest to the desired frequency, with a step size displayed in the LCD.
1.4.11 Using the External Mixer
The FireFox Signal Generator includes a general purpose mixer accessible from the front panel. A
mixer is used to generate a signal consisting of the difference of two input signals. Mixers can be
used to shift high-frequency signals into lower frequency bands, or vice versa.
As an example, the FireFox Signal Generator can be used to modulate baseband video signals to RF
channel frequencies. Analog or Digital signals such as DVB-T baseband signals can be upconverted
to RF frequencies up to about 400MHz. To RF modulate an I/Q baseband DVB-T video signal to an
RF carrier of 61.25MHz, simply set the RF output of the FireFox Signal Generator to 61.25MHz,
feed the RF output into the LO Mixer input (set the RF output amplitude to 0dBm, making sure not
to exceed the Mixer input damage level of +10dBm), and feed the DVB-T baseband signal into the
mixers RF input. The Mixer output will now contain a DVB-T modulated signal with a 61.25MHz
carrier. A VSB filter may have to be used to properly format the signal.
The mixer is also useful when trying to receive high frequency signals; see the following example:
An FM modulated signal at 1.40GHz is to be received using the FireFox and a standard FM radio.
The input signal has to be transformed from 1.40GHz to 100MHz to be receivable by the FM Radio.
For this example, we will select a Local Oscillator (LO) Frequency of 1.50GHz. The LO input is
simply driven by the FireFox RF output signal via a BNC jumper cable, so the FireFox is set to
generate the 1.5GHz. The received RF input signal is then connected to the RF input. Mixing the
1.5GHz LO frequency with the 1.4GHz RF signal will generate a 100MHz mixing product (the
Intermediate Frequency, or IF signal), which is basically the RF signal shifted to 100MHz. The IF
output can now be connected to the FM radio tuned to 100MHz. The received signal will now be
audible by the radio.
UL
The OCXO is not locked to UTC (Unlocked)
BG
The unit is receiving sufficient Satellites for Auto Survey
mode, but the Satellite Geometry is bad and the present
Satellites cannot be used (Bad Geometry)
LCD STAT indicator
Meaning
Table 1-1: GPS Status Indicator Abbreviations
Summary of Contents for FireFox
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