271 DDS Function Generator with ARB

The 271 is a high performance function generator using Direct Digital Synthesis techniques.

 

High performance function generator

  • High stability 10 MHz DDS function generator
  • Arbitrary capability with storage for five user defined waveforms
  • Multiple standard and complex waveforms recalled from internal memory
  • Extensive modulation capabilities include sweep, AM, Gating, Trigger/Burst, FSK and Hop
  • GPIB and RS-232 interfaces

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.

Direct digital synthesis for accuracy and stability

Direct digital synthesis (DDS) is a technique for generating waveforms digitally, using a phase accumulator, a look-up table and a 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.

A wide range of waveforms

The Fluke 271 generates high quality sine, square and pulse waveforms over the full frequency range of 0.1 mHz to 10 MHz. Triangle waveforms, ramp waveforms and multi-level square waves can also be generated, subject to some limitations in the maximum useable frequencies. Variable symmetry/duty-cycle is available for all waveforms.

Arbitrary waveform capability

Arbitrary waveforms can be loaded via the digital interfaces and then used in a similar way to the standard waveforms.

Up to five arbitrary waveforms of 1024 10-bit words can be stored in non-volatile memory. The waveform clock is 27.48 MHz maximum. This facility considerably expands the versatility of the 271, making it suitable for the generation of highly complex waveform patterns.

In addition, the 271 offers numerous “complex” waveforms pre-defined in ROM. These include commonly used wave shapes such as sine x/x, decaying sinewave, and exponential rise and fall.

Locked generators

The signals from the Clock In/Out socket and the Sync Out socket can be used to phase lock two or more generators. This feature can be used to generate multi-phase waveforms or locked waveforms of different frequencies.

Powerful modulation modes

Sweep.

All waveforms can be swept over their full frequency range at a rate variable between 10 milliseconds and 15 minutes. The sweep is fully phase continuous. Sweep can be linear or logarithmic, single or continuous. Single sweeps can be triggered from the front panel, the trigger input, or the digital interfaces.

Two sweep markers are provided, which are adjustable while sweep is running. The markers can provide a visual indication of frequency points on an oscilloscope or chart recorder.

AM.

Amplitude modulation is available for all waveforms and is variable in 1 % steps, up to 100 %.

FSK.

Frequency shift keying provides phase coherent switching between two selected frequencies at a rate defined by the switching signal source. The rate can be set from dc to 50 kHz internally, or dc to 1 MHz externally.

Trigger/Burst.

All waveforms are available as a triggered burst, whereby each positive edge of the trigger signal will produce one burst of the carrier, starting and stopping at the phase angle specified by the start-stop phase setting. The number of cycles in the burst can be set between 0.5 and 1023.

Gated.

The gated mode turns the output signal on when the gating signal is high and off when it is low. Both triggered and gated modes can be operated from the internal trigger generator (0.005 Hz to 50 kHz) or from an external source (dc to 1 MHz).

Waveform hop.

The generator can be set up to ‘hop’ between a number of different waveform setups, either at a pre-determined rate or in response to a manual or bus trigger. Up to 16 different hop waveforms can be defined in terms of frequency, amplitude, function, offset and duration, which is variable in 1 ms steps up to 60 seconds.

Noise generation.

The Fluke 271 can be set to simulate wide band random noise with adjustable amplitude and offset.

 

 

 

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 above the frequencies indicated in the following section.
Range: 0.1 mHz to 10 MHz
Resolution: 7 digits or 0.1 mHz
Accuracy: Typically < ± 10 ppm for 1 year, 18 °C to 28 °C
Tempco:. Typically < 1 ppm/°C outside 18 °C to 28 °C
Sinewave
Distortion: < –60 dBc to 20 kHz, < –50 dBc to 300 kHz, < -35 dBc to 10 MHz
Spurii: Non -harmonically related spurii typically <- 60 dBc to 10 MHz
Squarewave
Rise and fall times: < 22 ns
Triangle
Linearity error: < 0.5 % to 30 kHz
Positive and Negative Ramp
Linearity error: < 0.5 % to 30 kHz
Positive and Negative Pulse
Rise and fall times: < 22 ns
Multi-Level Squarewave
Up to 16 steps available per cycle, each step selectable for amplitude (10 bit resolution) and duration (1 to 1024 samples). Above 27 kHz a 36 ns edge uncertainty is introduced.
Rise and fall times: < 22 ns
Arbitrary (and complex)
A number of “complex” waveforms are pre-programmed in ROM . A further five, user defined, waveforms may be loaded via the digital interfaces and stored in non-volatile RAM. Frequency range: All waveform points can be continuously output up to 27 kHz, beyond which 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,
20 % to 80 % to 10 MHz
Resolution: 0.1 %

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

(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 50Ω/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

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

Operating Modes
Trigger/burst
Phase coherent signal keying — each positive edge of the trigger signal will produce one burst of the carrier, starting and stopping at the phase angle specified by the start/stop phase setting
Carrier frequency: 0.1 mHz to 10 MHz
Carrier waveforms: All
Number of cycles: 1 to 1023 (resolution 1 cycle) or 0.5 to 511.5 (resolution 1/2 cycle)
Trigger rep. rate: dc to 50 kHz internal, dc to 1 MHz external
Source: Internal from keyboard or trigger generator. External from EXT TRIG input or remote interface
Gated
Non phase-coherent signal keying — output is On while Gate signal is high and Off while low.
Carrier frequency: From 0.1 mHz to 10 MHz
Carrier waveforms: All
Trigger rep. rate: dc to 50 kHz internal dc to 1 MHz external
Gate source: Internal from keyboard or trigger generator. External from EXT TRIG input or remote interface
Sweep
Carrier waveforms: All
Sweep mode: Linear or logarithmic, single or continuous
Sweep width: 0.1 mHz to 10 MHz. Phase continuous. Independent setting of the start and stop frequency.
Sweep time: 10 ms to 999 s (3 digit resolution)
Markers: Two markers variable during sweep. Available at the TRIG/SWEEP OUT socket
Sweep trigger source: The sweep may be free run or triggered from: keyboard, EXT TRIG input, remote interface
Hop
Up to 16 different “hop” waveforms can be defined in terms of function, frequency, amplitude, offset and duration. Duration setable per step 1 ms to 60 s.
Start/Stop Phase
Carrier frequency: 0.1 mHz to at least 1 MHz
Carrier waveforms: All
Range: –360 to +360 degrees
Resolution: 1 degree
Accuracy: Typically 1 degree to 30 kHz
Trigger Generator Internal source 0.005 Hz to 50 kHz squarewave adjustable in 20 us steps. 3 digit resolution. Available for external use from TRIG/SWEEP OUT socket.
Auxiliary Outputs
Aux Out CMOS/TTL levels with symmetry and frequency of main output and phase of start-stop phase setting
Trig/Sweep Out Multi-function output depending upon mode. Except in sweep mode, the output is that of the trigger generator at CMOS/TTL levels from 1 kW.

In Sweep mode the output is a 3-level waveform, changing from high (+4 V) to low (0 V) at the start of sweep, with narrow 1 V pulses at each marker point.

Inputs
Ext Trig
Frequency range: DC to 1 MHz
Signal range: TTL (1.5 V) threshold; maximum input ± 10 V
Min. pulse width: 50 ns
VCA In
Frequency range: DC - 100 kHz
Signal range: 2.5 V for 100 % level change at maximum output
Input impedance: Typically 6 kΩ

Phase Locking
Clock in/out TTL/CMOS threshold levels; output impedance typically 50 Ω as an output
Sync out TTL/CMOS logic levels from typically 50 Ω. The signals from these sockets are used to phase lock two or more generators.

Interfaces
RS-232 Variable Baud rate, 9600 Baud maximum. 9-pin D-connector.
IEEE-488 Conforming with IEEE488.1 and IEEE488.2

General Specifications
Display 20 character x 4 row alphanumeric LCD
Data entry Keyboard selection of mode, waveform etc.; value entry direct by numeric keys or by rotary control.
Stored settings Up to 9 complete instrument set-ups may be stored and recalled from battery-backed memory.
Size 3U (130 mm) height; half-rack (212 mm) width, 330 mm long
Weight 4.1 kg (9 lb)
Power 100 V ac, 110 to 120 V ac or 220 to 240 V ac +/– 10 %, 50/60 Hz ac by internal adjustment; 30 VA max.
Operating range +5 °C to 40 °C, 20 to 80 % RH
Storage range –20 °C to +60 °C
Options IEEE-488 interface; 19-in rack mounting kit

 

 

Model Name

Description
271 10 MHz DDS Function Generator with Serial Cable

Accessories common to all models:

Accessory

Description
Y200H Rack Mount Kit

 

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