NOVATECH INSTRUMENTS
40 MHz Lockable Digital Synthesizer Module
Model DDS5m
Photo
Last Modified January 10, 2001
The DDS5m Lockable Digital Synthesizer Module is a Precision
40 MHz Signal Source on a small circuit board. The DDS5m can be locked
to an external frequency standard to provide accuracy and stability
equal to the standard. It provides both Sine and Clock outputs from
100 Hz to 40 MHz in 0.025 Hz steps. The RS232 serial interface makes
it easy to set the output frequency and save the settings in EEPROM
memory. Rotary switches also aIlow for setting the frequency
manually. The DDS5m has excellent spectral purity and contains a
quartz crystal oscillator with better than 5 ppm accuracy. Multiple
DDS5m can be locked together using an external clock and the phase is
programmable in 11.25 degree increments.
Specifications
OUTPUT
Types: Simultaneous Sine, ACMOS (TTL compatible) and unfiltered Sine
Impedance: 50 Ohms
Frequency: 100 Hz to 40.000 MHz in 0.025 Hz steps
OUTPUT AMPLITUDE
Sine: Approx. 1 Vrms into open circuit, 0.5 Vrms into 50 Ohms
ACMOS: (TTL Compatible) Vol: 0.5 V max, Voh: 3.5 V min into 30 pF, <5 ns rise and fall times
FREQUENCY CONTROL
Manual: Rotary switches allow setting in 0.1 Hz steps up to 40.000 MHz.
Serial: RS232 interface allows setting of frequency to 0.025 Hz. Fixed at 9600 baud. Internal (default) or external frequency update input can be used to synchronize frequency change.
PHASE CONTROL
Serial interface allows setting phase in 11.25 degree increments. An unlimited number of DDS5m can be phase synchronized together using an externally supplied CMOS level sync pulse. (When used with 1 MHz external standard.)
SPECTRAL PURITY (Typical)
Phase Noise: <-130 dBc @ 1 kHz offset @ 5 MHz out
Spurious: <-55 dBc below 10 MHz
<-45 dBc below 40 MHz
Harmonic: <-55 dBc below 10 MHz
<-40 dBc below 40 MHz
ACCURACY AND STABILITY (Using Internal Clock)
Accurate to < +/- 5 ppm @ 25 C +/- 5 C, 24 hrs
Stable to +/- 10 ppm per year at 25 C +/- 5 C
EXTERNAL STANDARD
The DDS5m will lock to and track an external standard of 1, 2, 5 or 10
MHz to + 2 ppm minimum. The locked accuracy and stability is
dependent upon the accuracy and stability of the external standard.
Jumper selectable. 50 W input impedance. The external standard can be
0.5 to 3 Vrms, sine or square wave.
CONNECTIONS
SMB for ACMOS out, Sine out and External Standard input. Five pin Molex # 22-23-2051 for power. DE9F for RS232.
POWER
+5 Vdc +/- 0.1 Vdc @ <350 mA
-5 Vdc +/- 0.1 Vdc @ <50 mA
< 50 mV noise and ripple
ENVIRONMENTAL
Operating Temperature: 5 C to 40 C
Humidity: 80% to 31 C, decreasing linearly to 50% at 40 C
SIZE
4.5 in by 5.5 in (11.4 cm by 14 cm)
SERIAL COMMANDS
F XX . XXX XXX XXX Sets frequency in MHz. Software sets to
nearest 0.025 Hz setting. 1 MHz default.
Decimal point required.
E D Disables echo.
E E Enables echo.
R Reset. Same as cycling power.
P N N is integer 0 to 31. Phase is set to
N*11.25. (N*Pi/16 radians)
A E Enables ACMOS/TTL output.
A D Disables ACMOS/TTL output.
Output is set low. (Lowers system
noise for critical applications)
SAVE Save current setting in EEPROM. Used
as default upon power up.
QUE Return current setting
PRICING
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Novatech Instruments , Inc.
P.O. Box 55997
Seattle, WA 98155 USA
Return to Homepage: http://www.eskimo.com/~ntsales.html
Technical Questions: novatech@eskimo.com