Stanford Research Systems DS345, Manual

Page: 87 / 139

Performance Tests
5-9
PHASE NOISE
This test measures the integrated phase noise of the DS345's output in a 15
kHz band about carrier. This test is performed at 10 MHz to minimize the
contribution of discrete spurs to the measurement.
specification: < -50 dBc in a 15 kHz band centered about the carrier, exclu-
sive of discrete spurious signals.
1) Connect the equipment as shown in the diagram below. The 1 MHz filter
removes the sum frequency mixer output, and the 15 kHz filter sets the noise
bandwidth of the measurement.
2) Set the DS345 to sine wave, 10.001 MHz, +13 dBm. The frequency stan-
dard should be 10 MHz, > +10 dBm.
3) Record the AC voltage reading.
4) Set the DS345 to 10.0 MHz. Measure the DC signal from the mixer. Use
the DS345's PHASE control to minimize the DC voltage value.
5) Set the voltmeter to AC and measure the mixer output. Calculate the ratio
of this voltage to that obtained in step 3 ( dB = 20 log (V
5
/V
3
)). Add -6 dB to
this value to compensate for the mixer. This value should be less than -55
dB. Record the result.
OUTPUTS
FUNCTION
SYNC
REM SRQ
ACT ERR
EXT ERR
ARB
NOISE
BURST
Φ
FM
AM (INT)
LOG SWP
LIN SWP
m
TRIG'D SINGLE
ARB
MOD/SWP SHIFT
Hz dBm
DEG Vrms
% Vpp
FREQ AMPL OFFS PHASE TRIG STEP SPAN RATE MRK STRT f STOP f
ON/STBY
SRS
STANFORD RESEARCH SYSTEMS MODEL DS345 30MHz SYNTHESIZED FUNCTION GENERATOR
TIMEBASE
STATUS
50 Ω 40V max.
TTL
ECL
TTL
REL=0
TRIG SWP CF
BRST CNT
STOP f
MRK START
GPIB
TRIG SOURCE
MRK STOP
SRQ
TRIG RATE
ARB EDIT
MRK CF
RS232
MRK=SPAN
DEFAULTS
MRK SPAN
DATA
SPAN=MRK
CALIBRATE
LOCAL
AMPL
FREQ
OFFST
PHASE
RATE
SWEEP
ON/OFF
SPAN
(DEPTH)
START
FREQ
SHIFT STO RCL CLR
DEG
%
MHz
dBm
kHz
Vrms
Hz
Vpp
STEP
SIZE
0
.
+/-
1
4
7
2
5
8
3
6
9
FUNCTION MODULATION
FUNCTION SWEEP/MODULATE MODIFY ENTRY
DS345
10.000000000 MHz
Frequency Standard
RF
IF
LO
Mixer
1 MHz Lowpass
Filter
11.0 k
Ω
1%
0.0015
µ
F 5%
15 kHz Lowpass
Filter
50
Ω
1.23 V
AC/DC Voltmeter
Figure 6-1. Phase Noise Measurement
10