Orban OPTIMOD-FM 8500S Operating Manual page 264

4-12
MAINTENANCE
An analog oscilloscope can be used for a more thorough test. Set the
scope for X/Y operation (i.e., so that it generates Lissajous patterns).
Connect the reference generator to one input and the 8500S's digital
output to the other input. If correct synchronization is occurring, you
should see an essentially stationary (although complex-looking) Lissajous
pattern as opposed to one that precesses slowly either left or right. This
should be true at any combination of input and output sample frequen-
cies and a thorough test will test every permutation.
This test verifies that for non-identical reference and output sample fre-
quencies (for example, locking a 32 kHz output sample rate to a 48 kHz
wordclock), the output and input sample rates are exactly a ratio of inte-
gers. In the example, the output sample rate is exactly 2/3 of the word-
clock frequency.
A digital oscilloscope is unlikely to work satisfactorily for this test.
D) Connect either a source of 1x wordclock (a TTL-level squarewave at the sam-
ple frequency) or a high-accuracy 10 MHz sinewave or squarewave generator
to the 8500S's R
put by ±25 ppm and verify that the 8500S's output sample rate tracks it. See
the comments in step (C) above.
E) Set the 8500S's P
F) Sequentially apply AES3 or AES11 signals having 32kHz, 44.1 kHz, 48 kHz, 88.2
kHz, and 96 kHz sample frequencies to the 8500S's AES3 Digital Input. Using
the oscilloscope technique described in step (C) above, verify that for each in-
put sample frequency, any 8500S output sample frequency (as set via the DO
control) will lock to any reference sample frequency.
R
ATE
G) Disconnect the generator from the 8500S's R
H) Set the P
R
ILOT EF
9. Test the 8500S's stereo encoder.
A) Connect an accurate stereo monitor like the Belar FMMS-1 ("Wizard") stereo
demodulator to the C
NOTE: The recommended Belar monitor is the only instrument we have
encountered that can accurately measure the performance of the 8500S's
stereo encoder. With most older-technology monitors, you will be meas-
uring the performance of the monitor, not the 8500S's encoder. (Of
course, we have not evaluated every monitor on the market.) While we
have not yet tested it, we are confident that the Belar FMCS-1 (a newer
model than the FMMS-1) will also work correctly.
B) On the 8500S, navigate to Setup > T
C) Set the M to T
ODE
D) Set the test tone parameters as follows:
T F ..........................................................................................400 Hz
ONE REQ
T L ................................................................................................ 91%
ONE VL
T C ............................................................................................... L+R
ONE HAN
P ......................................................................................................... On
ILOT
BNC connector. Vary the frequency of the reference in-
I
EF N
control to D
S
ILOT YNC
control to I .
NTERNAL
O
OMPOSITE UTPUT
EST
.
ONE
ORBAN MODEL 8500S
I .
IG N
I connector.
EF N
1 BNC on the 8500S's rear panel.
.