TTi TG2511A – 25MHz Function/Pulse/Arbitrary Generator, USB/LXI

• High resolution LCD
• USB Flash drive storage
• With variable delay, rise/fall
• Up to 50mhz sine and square

TGxx11 Series: Function/Arbitrary/Pulse Generators

The TGxx11 Series represents the state-of-the-art in DDS based function generators. The 50MHz TG5011 significantly outperforms other generators in its price range, not just because of its frequency range, but because of its all round performance and features.

The TG2511 incorporates a similar feature set at a still lower cost and represents exceptional value for those with lower frequency requirements. TTi manufactures a wide range of function, arbitrary and pulse generators from lower frequency analog units to multi-channel variable clock arbitrary generators.

The TG5011 out-performs other generators in its price range by offering both sine and square waves up to 50MHz. The lower cost TG2511 operates to 25MHz.

Exceptional frequency precision

The frequency of these waveforms can be set with up to 14 digits or one micro hertz of resolution. The DDS based frequency generation system uses a TCXO time-base oscillator with a stability of 1ppm.

Waveform Quality

The TG5011 and TG2511 generate high purity sine waves with low harmonic distortion and low phase noise. Square waves have a rise time of below 8ns (13ns on TG2511) and low overshoot. Variable symmetry can be used up to 25MHz.

Triangle and Ramp

High quality triangle and variable symmetry ramp waveforms are available up to 500kHz (TG5011) or 250kHz (TG2511). These waveforms are also available at higher frequencies via the arbitrary function but without symmetry adjustment and with reduced waveform quality as the frequency increases.

VLF generation

The high resolution of the DDS system means that very low frequencies can be set. For example, a frequency of around 1mHz could be set with a resolution of 0.1% and a stability of 1ppm.

Both models incorporate a pulse generator mode which provides wide range pulse width and delay independent of period. Rise and fall times (edge speeds) are also fully variable.

On the TG5011, the pulse period can be set between 80ns and 2000 secs. (0.5mHz to 12.5MHz) with a resolution of 14 digits or 1μHz. On the TG2511, the minimum pulse period is 160ns (6.25MHz).

Fully variable pulse Width and Delay

Pulse width and pulse delay can be independently set to a resolution of 10ns. Minimum pulse width is 20ns and duty cycles can be as low as one in two billion.

Independently variable Rise and Fall

The generators offer very fast edge speeds of better than 8ns on the TG5011 or 13ns on the TG2511, but the edges can be slowed down to simulate slower pulses.

Rise and fall times are independently variable in the range 5ns to 40us (10ns to 40us on the TG2511), or can be linked so that both edge speeds are the same.

Trigger, Burst and Gate

As with all other waveforms, pulses can be triggered from an external trigger input (or manual trigger, the internal trigger generator or a Bus command). Burst mode creates a burst of between one and a million pulses in response to each active edge of the trigger. Gated cause pulses to be generated only when the gate signal is true. The gate source can be external or internal exactly as the trigger signal.

Both generators offer DDS generated arbitrary waveforms capability. A number of standard waveforms are included, and up to four user defined arbitrary waveforms can be stored in the instrument at any one time.

Waveforms have a vertical resolution of 14 bits (16,384 amplitude levels). Waveforms can be created using between 2 and 131,072 points (128k). The sampling rate is 125MHz and DDS techniques are used to provide any repetition rate between 1uHz and 10MHz (TG5011) or 6MHz (TG2511) with up to 14 digits of frequency resolution.

Internal and External Waveform Storage

Up to four user defined waveforms totalling up to 256k words can be stored within the permanent internal memory of the instrument. However, a front mounted USB port enables external Flash memory storage of up to 1000 waveforms of any size. This memory stick also provides a quick and convenient method for transferring waveform files to and from a PC. It can also be used for storing instrument set-ups.

Pre-built Complex Waveforms

Commonly used complex waveforms are provided both built-in to the instrument and for loading into the user defined waveform space. These include sin(x)/x, exponential rise and fall, logarithmic rise and fall, gaussian, lorentz, haversine and cardiac waveforms.

Waveform Creation & Editing

Arbitrary waveforms can be created and edited using the simple tools built into the instrument. However, complex waveforms require an external PC based editor.

Both instruments are supplied with Waveform Manager Plus for Windows® which provides the most comprehensive set of waveform tools available including a mathematical expression editor, freehand drawing, waveform libraries, and import of waveforms using the Clip Board. More information is provided on Page 5 of this brochure.

Both instruments incorporate a front mounted USB socket for connection of flash memory disk drives which can store up to 1,000 waveforms and 1,000 setups.

These drives can be used both to store waveforms permanently and to transfer waveforms from or to a PC. Arbitrary waveform storage within the instrument is limited to four waveforms. Each flash drive can store up to 1000 waveforms which can be accessed using the instruments file handling utilities.

Up to nine complete set-ups of the instrument can be stored within its own non-volatile memory. Up to 1000 further set-ups can be stored on each flash drive.

Both generators offer a comprehensive set of digitally based modulations. The internal modulation source can use any of the standard or arbitrary waveforms currently within the generator (including noise) thus removing the need for an external modulation source.

A modulating frequency between 1μHz and 20kHz can be specified. An external modulation input enables any external waveform source to be used when required. The external bandwidth is DC to 20kHz.

Sine, square, ramp or arbitrary waveforms can be modulated using amplitude, frequency or phase modulation. Amplitude depth is variable from 0.0% to 120.0%, frequency deviation from zero to Fmax/2, and phase deviation from -360.0 to +360.0 degrees.

PWM

Pulse width modulation is available for the pulse function using any standard or arbitrary waveform including noise. Pulse width deviation is variable between 0% and 100%.

FSK

Frequency shift keying between any two frequencies is available for sine, square, ramp or arbitrary waveforms using the internal trigger generator or an external trigger signal. The internal trigger generator is variable between 2mHz and 1MHz with nine digit resolution.

Sweep, Burst and Gated modes of operation are available using either an external trigger signal or the internal trigger generator.

Phase continuous sweep is available for all standard and arbitrary waveforms except for pulse. The sweep range is from 1μHz through to the maximum for the chosen carrier waveform. Start and stop frequencies can be set independently.

The sweep can be linear or logarithmic, triggered or continuous with a period between 1ms and 500s. The sweep trigger can be manual or internal from the trigger generator or external from the trigger socket or from a remote interface command. A marker is provided that outputs an edge synchronous with any frequency point within the sweep.

Triggered Burst

In Burst mode, each active edge of the trigger will produce one burst of the waveform. The number of cycles in a burst can be set between 1 and 1,048,575 (or infinite). The burst starts and ends at a waveform phase angle settable between -360.0 to +360.0 degrees.

Trigger signal

The trigger signal can be manual from the front panel key, internal from the internal trigger generator, external from the trigger-in socket, or remote via a bus command.

The trigger-in socket has a nominal TTL threshold and can be set to +ve edge or -ve edge triggering. The minimum trigger pulse width is 50ns. The internal trigger generator is variable between 2mHz and 1MHz with 9 digit resolution.

Gated

In Gated mode the waveform runs only when the gate signal is true. The start point of the waveform is settable from -360.0 to +360.0 degrees and a the last cycle is completed after the gate signal goes false. All of the options available for triggering are available for gating. The trigger-in socket can be set as high or low for true.

Both models can generate gaussian white noise to a -3dB bandwidth of 20MHz. The noise generation algorithm achieves a high crest factor (peak to rms ratio) of 5.27.

Adding Noise to a waveform

Noise can be added to any waveform except pulse. The amount of noise added can be specified as 0% to 50% of the amplitude of the carrier waveform.

Modulating with Noise

Noise can be used as the modulating waveform for AM, FM, PM or PWM modulations using any of the carrier waveforms allowable for that modulation type.

Both the models include external reference and phase locking as standard, unlike some competitor products for which they are an expensive option.

External Frequency Reference

The generators use a high quality TCXO crystal as the internal frequency reference providing 1ppm accuracy and stability. If a higher accuracy or stability is required, an external 10MHz reference signal (from an off-air standard for example) can be applied to the Ref. Clock input.

Phase Locking Two Generators (or more)

Two generators can be synchronised together to provide outputs at the same frequency (or at harmonics) and with a phase difference. The amplitude and phase of these outputs can also be modulated providing the capability to perform QAM and QPSK respectively.

Any waveform other than pulse can be used, and the phase difference is adjustable between -360.0 and +360.0 to a resolution of 0.1 degrees. Skew is better than 5ns. It is also possible to synchronise more than two generators but the resulting precision is not specified.

All functions of the generators can be controlled from the digital interfaces. Arbitrary waveform data can also be loaded using these interfaces.

An IVI driver for Windows is supplied. This provides support for common applications such as LabView*, LabWindows* and HP-VEE*.

G versions of the products are fitted with a GPIB (IEEE-488) interface. They retain both the other interfaces, giving them even greater flexibility.

USB provides a simple and convenient means of connection to a PC and is particularly appropriate for small system use. USB has effectively replaced RS232 in many applications. The interface uses a standard USB 2.0 hardware connection and is implemented as virtual-COM port. A Windows* USB driver is provided. As well as the rear mounted USB device interface connector, a front mounted USB Host interface connector allows USB Flash memory to be connected.

The LAN interface uses a standard 10/100 base-T Ethernet hardware connection with ICMP and TCP/IP Protocol for connection to a Local Area Network or direct connection to a single PC. This interface supports LXI and is the most appropriate for larger system use because of its scalable nature.

The LAN interface is compliant with LXI (LAN eXtensions for Instrumentation) class C. LXI is the next-generation, LAN-based modular architecture standard for automated test systems managed by the LXI Consortium, and is expected to become the successor to GPIB in many systems.

• LabView and LabWindows are trademarks of National Instruments. HPVEE (now Agilent VEE) is a trademark of Agilent Technologies.
• USB interface is supported for Windows 2000, XP, Vista and Windows 7. Windows is a trademark of Microsoft Inc.

The high waveform quality with its low aberrations is available over a wide amplitude range of 20mV to 20V pk-pk emf (10mV to 10V into 50 W). DC offset is provided independently of waveform attenuation so, for example, a waveform amplitude of millivolts can be combined with a dc level of volts.

Amplitudes can be displayed as peak to peak or as RMS values, with the rms being correctly calculated for the waveform shape. RMS values can alternatively be specified in dBm. If preferred values can be entered in terms of high level and low level instead of amplitude and offset.

The amplitudes are shown relative to the selected load impedance which is 50 W (or High-Z) by default, but can be selected as any impedance between 1 W and 10 kW.

The Sync output provides a logic level signal that can perform a number of functions intended for synchronization with external equipment:

• Normal Waveform
• Sync Modulation Sync
• Burst Sync
• Sweep Sync (with sweep marker)
• Trigger Signal Out
• Phase Lock (for 2nd generator)

The signal type can be selected manually or automatically dependent upon the function in use.

In addition to the digital bus interfaces, the rear panel carries four I/O sockets:

• External Modulation Input – for AM, FM, PM and PWM external modulation.
• Trigger Input – for external triggering of Burst, Gated or Sweep waveforms.
• Reference Clock Input – for use with an external frequency reference or phase locking of two generators.
• Reference Clock Output – a buffered version of whichever clock (internal or external) that the generator is using.

Waveform Manager Plus is a Windows* based application for creation, editing and management of arbitrary waveforms using a PC.

It incorporates a complete suite of tools for waveform creation and editing including standard waveforms, mathematical expressions and freehand drawing. Virtually any waveform can be created using combinations of these tools.

Mathematical Expression Editor

The sophisticated mathematical expression editor allows geometric, logarithmic and pulse functions to be combined to create exact representations of complex signals. Different expressions can be used for different sections of a waveform and can be combined with imported waveforms or drawn waveforms where mathematical representation is not possible.

Import of Other Waveforms

The program offers direct import from .csv files, the most commonly used format for graphical description. Additionally a Clipboard import function supports any waveform that can be described by a set of Y-axis data points regardless of their format.

Any instrument or waveform generating program that can create a list of Y values can therefore be accommodated. This is a highly flexible method which can be used to create arbitrary generator waveforms from signals captured by instruments such as oscilloscopes and network analysers, or from software such as MathCad.

The 3.6″ diagonal panel uses 256 x 112 pixels and provides a large amount of simultaneous information. System connection information is shown on the top line. Below that is a general status screen showing five major parameters. These parameters change depending upon the function being used.

Below the status information is the main editing line which shows the parameter currently under control.

The area the to right of the status section shows a representation of the current waveform. This is more than just a fixed display for each waveform, it is calculated from the waveform parameters and gives a live indication when values such as symmetry, rise time or pulse width are changed. Even user defined arbitrary waveforms are shown (subject to the limitations of the display resolution).

Modulation waveforms and representations of the modulated carrier are shown simultaneously. Burst count waveforms are also shown graphically

Six soft keys below the display provide access and control of the parameters for each function. All numeric parameters can be set directly from the numeric keypad, or can be changed using the spin wheel.

Period entry can be chosen instead of frequency, and amplitude and offset can be changed to Hi and Lo levels. Frequencies can be entered in any units from uHz to MHz, periods from ns to seconds, and amplitudes in mV or V, rms or pk-pk, or in dBm

The currently selected waveform and major functions are also indicated by illumination of the respective keys.

The generators are highly compact and use a minimum of bench space. Protective mouldings guard against knock damage and a multi-position stand angles the instrument conveniently as well as providing a carry handle.