Fluke 271 User Manual

271 DDS Function
Generator with ARB

Function
Generators

High performance function generator

n

High stability 10 MHz DDS
function generator

n

Arbitrary capability with
storage for five user
defined waveforms

n

Multiple standard and
complex waveforms
recalled from internal
memory

n

Extensive modulation
capabilities include sweep,
AM, Gating, Trigger/Burst,
FSK and Hop

n

GPIB and RS-232
interfaces

Tech Tip

Direct digital synthesis
(DDS) is a technique for
generating waveforms
digitally using a phase
accumulator, a look-up
table and a digital-to­analog-converter (DAC).
The accuracy and
stability of the result­ing waveforms is
related to that of the
crystal master clock.
The DDS generator
offers not only excep­tional accuracy and
stability but also high
spectral purity, low
phase noise and excel­lent frequency agility.

The 271 is a high performance function generator using
Direct Digital Synthesis techniques. A wide variety of
standard waveforms are provided and an arbitrary
waveform capability allows it to be used to generate
non-standard and user-defined waveforms. Extensive
modulation capabilities make this a highly versatile
signal source.

Waveforms

Standard waveforms are sine, square, positive pulse,
negative pulse, triangle, ramp up, ramp down. Addi­tionally arbitrary waveforms, multi-level squarewaves,
waveform hopping and pseudo-random noise can be
generated.

Signal Sources

225

271 DDS Function
Generator with ARB

Function Generators

Waveforms

Frequency

All waveforms are available up to 10 MHz. However, the purity of triangle, ramp, and multi-level square wave waveforms is not specified

ove the frequencies indicated in the following section.

ab
Range 0.1 mHz to 10 MHz
Resolution
Accuracy Typically < ± 10 ppm for 1 year, 18 °C to 28 °C

empco. Typically < 1 ppm/°C outside 18 °C to 28 °C

T

Sinewave

Distortion < –60 dBc to 20 kHz, < –50 dBc to 300 kHz, < -35 dBc to 10 MHz
Spurii

Squarewave

Rise and fall times < 22 ns

Triangle

inearity error < 0.5 % to 30 kHz

L

Positive and Negative Ramp

inearity error < 0.5 % to 30 kHz

L

Positive and Negative Pulse

Rise and fall times < 22 ns

Multi-Level Squarewave

6 steps available per cycle, each step selectable for amplitude (10 bit resolution) and duration (1 to 1024 samples). Above 27 kHz a

Up to 1
36 ns edge unc

Rise and fall times < 22 ns

Arbitrary (and complex)

A numb
interfac
they are sampled.

No. of samples 1024 10 bit samples
Noise Wideband noise with variable amplitude and offset.

Symmetry

Range Sine — 1 % to 99 % at all frequencies; Other waveforms — 1 % to 99 % to 30 kHz,

Resolution 0.1 %

ertainty is introduced.

er of “complex” waveforms are pre-programmed in ROM . A further five, user defined, waveforms may be loaded via the digital

es and stored in non-volatile RAM. Frequency range: All waveform points can be continuously output up to 27 kHz, beyond which

7 digits or 0.1 mHz

Non -harmonically related spurii typically <- 60 dBc to 10 MHz

20 % to 80 % to 10 MHz

Main Output

Output impedance 50 Ω or 600 Ω switchable
Amplitude 5 mV to 20 V pk-pk open circuit (2.5 mV to 10 V into 50

(open circuit value) or V (Voltage into the characteristic impedance) in pk-pk, RMS or dBm. Note that in

positive or negative pulse modes the amplitude range is 2.5 mV to 10 V pk-pk O/C.
Accuracy Typically ±3 % ±1 mV at 1 kHz into 50 Ω/600 Ω
Flatness ±0.2 dB to 500 kHz; ±1 dB to 10 MHz
Pulse aberrations <5 %+ 2 mV
DC offset ± 10 V from 50 Ω/600 Ω offset plus signal peak limited to ± 10 V from 50 Ω/600 Ω
Resolution 3 digits or 1 mV for both amplitude and offset

Ω/600 Ω). Output can be specified as V-H: 2

Modulation

Amplitude Modulation

Carrier frequency 0.1 mHz to 10 MHz
Carrier waveforms All
Depth 0 to 100 %, resolution 1 %
Internal source 1 kHz fixed sinewave or 0.005 Hz to 50 kHz square wave
External See “VCA In” section

Frequency Shift Keying (FSK)

Phase coherent switching between two frequencies at a rate defined by the switching signal source
Carrier frequency 0.1 mHz to 10 MHz
Carrier waveforms All
Switch repetition rate dc to 50 kHz internal, dc to 1 MHz external
Switching signal source Internal from keyboard or trigger generator. External from EXT TRIG input or remote interface.

226 Signal Sources