Orban OPTIMOD-FM 8700, Operating Manual

Page: 287 / 390

OPTIMOD-FM DIGITAL MAINTENANCE
4-11
I) Disconnect the oscillator and THD analyzer from the 8700i.
6. Test Digital Sample Rate Converter (Receiver).
A) Verify 8700i software controls are set to their default settings. (Refer to page
4-7.)
B) Be sure you are still in
BYPASS
mode [see step (3.F)].
C) Navigate to
I
NPUT
/
OUTPUT
. On screen
I
NPUT
/O
UTPUT
> I
NPUT
,
S
ET
I
NPUT
T
O
:
D
IGITAL
.
D) Connect the digital source generator to the AES3 Digital Input XLR connector
of the 8700i.
E) Set the frequency of the digital source generator to 400 Hz and its output lev-
el to 6 dB below full scale.
F) Inject the Digital Input with a sample rate of 32 kHz, 44.1 kHz, 48 kHz, 88.2
kHz, and 96 kHz. Use 24-bit words.
G) Listen to the analog outputs of the 8700i and verify that the output sounds
clean and glitch-free regardless of the input sample rate.
H) Leave the digital source generator connected to the 8700i.
7. Test Digital Sample Rate Converter (Transmitter).
A) Set the sample rate of the digital source generator to 48 kHz.
B) Navigate to Screen I
NPUT
/O
UTPUT
> O
UTPUT
1 .
C) Connect an AES3 analyzer (like the Audio Precision System 2) to the 8700i’s
AES3 digital output #1.
D) Change the S
AMP
R
ATE
to 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, and 96 kHz, and
verify that the frequencies measured at the 8700i’s AES3 output follow the
chart below within given tolerances:
Sample Rate Tolerance (PPM) Tolerance ( Hz)
32 kHz 50 PPM ±1.60 Hz
44.1 kHz 50 PPM ±2.20 Hz
48 kHz 50 PPM ±2.40 Hz
88.2 kHz 50 PPM
±
4.41 Hz
96 kHz 50 PPM
±
4.80 Hz
E) Navigate to Screen
I
NPUT
/O
UTPUT
> O
UTPUT
2
and repeat steps (C) and (D) for
AES Output #2.
F) Disconnect the digital source generator from the 8700i.
8. Test the 8700i’s stereo encoder.
A) Connect an accurate stereo monitor like the Belar FMMS-1 (“Wizard”) stereo
demodulator to the 8700i’s
COMPOSITE OUTPUT 1 . This is labeled
OUTPUT
and appears on a BNC connector on the 8700i’s rear panel.