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PTS offers one of the most complete lines of frequency synthesizers
available in the industry. Our models all use our own direct synthesis
systems. Their advantages over competitive designs include excellent
specifications with low phase noise, fast switching speed and low
spurious outputs along with low complexity.
Each model is a direct frequency synthesizer capable of providing
signals for many uses requiring stable and accurate sine-wave signals
with low spurious outputs, low phase noise and fast switching between
selected frequencies. Typical applications include wireless communications,
precision clock sources, radar and surveillance systems and automatic
test systems (ATE) with both narrow and wide-band coverage. Options
based on a modular design concept permit a high degree of adaptation
to a customer's specific needs.
To learn more about our product specifications and pricing, request
a catalog today. If you have questions about applicability or
performance detail, contact
PTS; demonstrator models are available for evaluations. |
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INTRODUCTION
TO PTS SYNTHESIZERS
PTS
frequency synthesizers are precision frequency generators. They
transfer the accuracy and stability of a frequency standard operating
at 5.0 or 10.0 MHz, either built-in or external, to a selectable
output frequency.
Each model is a direct frequency synthesizer capable of providing
signals for many uses requiring stable and accurate sine-wave signals
with low spurious outputs, low phase noise and fast switching between
selected frequencies. Typical applications include communications,
spectrum analysis and surveillance, radar and automatic test systems
(ATE) with both narrow and wide-band coverage. Options based on
a modular design concept permit a high degree of adaptation to a
customer’s specific needs.
Up to ten significant figures and resolution to 0.1 Hz are available;
custom higher resolution is also available. All output frequencies
are coherent with the standard frequency and reflect its stability
and accuracy. Any frequency within the instrument’s range may
be selected by manual dial or by remote control. The output from
the levelled system is +3 to +13 dBm (for most models) into 50 ohms
and may be adjusted manually by the front panel control or remotely
by analog voltage.
PTS synthesizers offer a choice of the two most widely-used
remote interfaces. Instruments may be equipped with either
the BCD-parallel (buffered) or the GPIB (IEEE 488) interface. In
addition, PTS now offers the industry's fastest GPIB list-processing
capability; this enhanced interface features full IEEE 488.2 and
SCPI capability.
The PTS systems of synthesis drastically cut complexity and parts
count. The attendant reduction of primary power input and dissipation
(less than 50% of that of competitive designs) is a major factor
in the reliability, which is further enhanced by a packaging system
maximizing mechanical integrity and stability while keeping weight
low. For ease of service, most modules are of plug-in design and
used in all models.
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REMOTE CONTROL INTERFACES
For remote-control or computer-controlled
applications, all PTS synthesizers are equipped with either a standard
parallel BCD interface, or an optional GPIB-compatible interface.
(Lower cost remote-only units are available which include no manual
control capability.) With both interfaces, output signal frequency,
output signal level, and remote/local mode control are programmable.
Parallel
BCD Interface
The
parallel BCD interface employs a 50-pin Amphenol 57-40500-compatible
connector on the equipment, and requires an Amphenol 57-30500-compatible
connector for control.
In the standard parallel BCD interface, output signal frequency
programming and remote/local mode control programming use TTL-level
negative true logic. Output signal level programming uses a DC control
voltage.
The programming format for frequency control is parallel, 4 bit
BCD coding for each digit (decade). All frequency programming connects
to, and can be driven by, industry standard 74HCT-type ICs. By default,
all frequency control lines are internally pulled to a high (false)
state; to program a specific frequency the appropriate pins must
be brought to the low (true) state.
Data latches are included which provide storage when a "latched"
or "buffered" mode of operation is required. By default,
all Latch Enable (LE) pins are internally pulled to a high (false)
state, disabling the latches. To store remote frequency programming
input, the LE pins are brought to the low state. To operate in a
"transparent" (i.e., non-latched) mode, the LE pins may
be left unconnected. A separate LE line is provided for each digit
pair (8 bits) so that operation with serial frequency programming
data bytes is possible.
The output signal level is programmed via a DC control voltage.
The RMS RF output voltage is one-half (0.5) the DC analog voltage
present on the output-level control pin (0.63 to 2.0 VDC, corresponding
to 0.315 to 1.0 Vrms output into 50 ohms).
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GPIB Interface
The GPIB interface employs an
IEEE-488 24-pin female connector on the equipment, and requires
an IEEE-488 24-pin male connector for control.
PTS offers two versions of the GPIB interface:
-a fast-switching legacy version which is IEEE 488.1(1987)-compliant.
It allows the synthesizer to act as a basic listener device (no
talk capabilities), and provides control of the two device-dependent
functions output signal frequency and level. Output signal frequency
can be programmed in 30 µseconds or less to the instrument’s
full resolution; signal level is programmed from + 4 dBm to +13
dBm in 1 dB steps.
-a fully IEEE 488.2/SCPI-compliant interface. It allows complete
control over all instrument functions and status. Switching speeds
are 5 - 10 mseconds, or less than 250 µseconds in the LIST
mode of operation.
The PTS GPIB can be controlled via special-purpose GPIB controllers.
Alternatively, a number of manufacturers provide low-cost board-level
products for microcomputers which implement the IEEE-488 interface.
The PTS GPIB remote-control interface is compatible with such products.
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FREQUENCY
SWITCHING BEHAVIOR
In
all PTS synthesizers, the most significant digits down to 1 MHz
(all produced by direct analog technology) have phase-coherent frequency
switching.
For applications requiring high-speed, phase-continuous frequency
switching, PTS offers the Direct Digital Synthesis Table Look Up
(DDS-TLU or DDS) option. With this option, the standard direct analog
low-resolution subsection of an instrument is replaced with a direct
digital subsection capable of generating the required low-resolution
frequency increments. The DDS can provide phase-continuous frequency
switching, and less than 1 µs switching time (with 2 µs
delay). The following versions are available:
- Version H – DDS option replaces
the 100 KHz through 0.1 Hz subsection. Phase continuity can
be maintained during frequency switches involving the 100 KHz
through 0.1 Hz digits. Spurious outputs are -60 to -70 dBc.
- Version K – DDS option replaces
the 10 KHz through 0.1 Hz subsection. Phase continuity can be
maintained during frequency switches involving the 10 KHz through
0.1 Hz digits. Spurious outputs are -65 to -75 dBc.
The DDS option is available for PTS
models 040, 120, 160, 250, 500 and 620. (DDS high speed, phase-continuous
switching is standard in the PTS model 310, 1600, 3200, 6400, x10,
D310 and D620.) Note that the spurious specifications for the versions
differ, reflecting the tradeoff between bandwidth coverage and spurious
output; consult instrument specifications for details.
In instruments using the analog mix-and-divide technology for steps
from 100 KHz down to 0.1 Hz, frequency switches have limited, though
arbitrary, phase discontinuities. In principle, a frequency switch
using the 100 KHz digit may have at most a 180° phase jump,
a frequency switch using the 10 KHz digit at most an 18° phase
jump, 1 KHz at most 1.8°, 100 Hz at most 0.18°, 10 Hz at
most .018°, 1 Hz at most .0018°, 0.1 Hz at most .00018°.
For all practical purposes, frequency switches of 100 Hz or less
may be considered phase-continuous in these instruments.
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FREQUENCY STANDARDS
The output frequency of a PTS synthesizer reflects directly the
accuracy of the controlling frequency standard, either internal
or external. PTS offers a choice of two internal standards: a high-stability
oven-controlled crystal oscillator (OCXO), or a moderate-stability
temperature-compensated crystal oscillator (TCXO).
All quartz crystal oscillators are secondary standards which require
a primary reference for calibration. PTS oscillators are set to
within 1x10-7 of nominal at the time of delivery from the factory.
Thereafter, these oscillators are subject to the time-drift and
temperature-drift given in the specifications. Both PTS oscillators
include field-adjustment capability for up to five years of aging.
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