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GPS - INTRODUCTION |
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GLOBAL POSITION SATELLITE (GPS) PRODUCTS |
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Teledyne KW Microwave Corporation has been designing and developing state-of-the-art
components for GPS applications since the mid 1980’s. The first application was
a preamplifier, L1 & L2, still in use today, primarily on fighter aircraft pod
mounted renage systems.
The use of GPS for military systems has been mandated by congress . The last of
the GPS satellites has been launched and the system is fully operational. Initial
developments by TKWM were for the encoded Precise Positioning Service (PPS); but,
TKWM has since manufactured components for commercial applications using the GPS
signal.
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PREAMPLIFER VS. LOW-LOSS CABLE |
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In many applications, the GPS receiver must be mounted remotely from the antenna
and the amount of interference is much worse than many systems/receiver designers
initially predicted. To accommodate the remote antenna and associated interference
problems, specialized filters, low-noise amplifiers and preamplifiers are required.
Why should a preamplifier be used when a high quality , low-loss cable can be used?
There are several reasons not to use the low-loss cable:
- Low-loss cables are very large, expensive and hard to handle.
- Low-loss cable degrades the noise figure by at least 0.5 to 1 dB for a 20 foot run.
- The extra weight of a low-loss cable becomes a concern on flight oriented applications.
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INTERFERENCE AND JAMMING |
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Many receivers utilize inexpensive ceramic filters in their front ends . These
filters typically have the first full spurious response as low as 2GHz and a multitude
of responses between 2 GHz and 18 GHz There are a variety of high power radar and
other original signal sources in this band that could effectively block or even
burn out a receiver without adequate filtering. Teledyne KW Microwave’s GPS preamplifier
and low-noise amplifiers are designed to filter out unintentional signals that are
near the GPS band.
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HIGH POWER PROTECTION |
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Teledyne KW Microwave has designed GPS low-noise amplifiers and preamplifiers with special
circuitry that inhibits and protects both the low-noise amplifier, preamplifier
and receiver from damage due to high power inband signals. |
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DESIGN CAPABILITIES |
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TKWM’s GPS engineers are capable of designing preamplifiers and low-noise amplifiers
with gain from 10dB to 40dB. As will be noted when reviewing TKWM’s part number GPS-1-14009
later in this section, TKWM engineers have developed a GPS Preamplifier which handles
313 watts of in-band pulsed power and up to 1 Kilowatt out-of-band.
TKWM GPS engineers have experience in the design of the entire GPS receiver system
and can apply that knowledge in product design.
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