NOVATECH INSTRUMENTS

PC Compatible 12 MHz Direct Digital Synthesizer

Model DDS3pc

Photo
Last Modified January 10, 2001

The DDS3pc Direct Digital Synthesizer is a 12 MHz Signal Source on an ISA Bus Card compatible with PC AT and later computers. It provides both sine and clock output signals from 2 Hz to 12 MHz in 2 Hz steps. The DDS3pc comes with a C-language program that makes it easy for the user to set frequency and attenuation. The user can automatically sweep through a set of frequency, attenuation and dwell time settings stored in a text file using the supplied software.

Specifications

OUTPUT

TYPES: Sine and HCMOS/TTL Simultaneously
IMPEDANCE: 50 ohms
RANGE: 2 Hz to 12 MHz in 2 Hz steps with internal
clock (to 16 MHz with degraded specifications)
SINE AMPLITUDE: +20 dBm (6.3 Vpp) into 50 ohms,
+26 dBm (12.6 Vpp) into open circuit (no attenuation)

SINE OUTPUT ATTENUATION

0 to 70 dB in 10 dB steps , ▒ 5% (+20dBm to -50dBm output, approx. 2.2 V to 707 ÁVrms into 50 ohms)

CONTROL

Output frequency, sinewave attenuation and clock source are set by four bytes of data in I/O address space starting at the base address set by an on-board switch (0338 Hex default). A C-language program is provided as an example. Both compiled and source code files are included. This program allows control of up to 1000 frequencies and amplitudes in the Command File mode or allows interactively setting frequency and amplitude.

SPECTRAL PURITY

PHASE NOISE: < -90 dBc at 1 KHz offset
SPURIOUS: Typically < -55 dBc below 5 MHz, < -45 dBc from 5 to 12 MHz
HARMONIC: < -50 dBc below 5 MHz, < -40 dBc below 12 MHz

ACCURACY AND STABILITY

Accurate to < ▒ 5 ppm at 25 ▒ 2 C, 24 hrs
Stable to ▒ 10ppm/year, 20 to 30 C

EXTERNAL CLOCK INPUT

The DDS3pc contains an internal 33.554432 MHz quartz crystal oscillator. It also accepts an external TTL/CMOS clock input of up to 40 MHz. The supplied program allows users to select the external input as the DDS3 PC system clock. An external clock will change the DDS3 PC step size in proportion to its ratio to the internal system clock. External output filtering may be needed when using an external clock lower than 33.55 MHz.

SWITCHING TIME

NOVATECH supplied software allows frequency to be set in nominal 1 mS time increments and automatically adjusts for PC system speed. Attenuation changes in 10 mS maximum, with maximum of 10 changes per second.

POWER REQUIREMENTS (From Slot)

Uses <250 mA @ +5 V, <100 mA @ -5 V and <50 mA @ ▒ 12V.

CONNECTORS

BNC's provided for Sine Output, HCMOS Output and External Clock Input.

PRICING

Click here to see our price sheet.


Novatech Instruments , Inc.

P.O. Box 55997
Seattle, WA 98155 USA
206.301.8986, novatech@novatech-instr.com, FAX 206.363.4367
Return to Homepage: http://www.eskimo.com/~ntsales.html
Technical Questions: novatech@novatech-instr.com