ZETRON 025-9581M, Installation And Maintenance Manual

Page: 121 / 196

121
Level Setting Procedures
Setting Station Transponder Unit Levels for a VoIP-based System
It may turn out that the factory default settings on the Station Transponder Units in your
system are adequate and you do not need to do any adjustments to the system beyond
adjusting the level at the VoIP Server. If you do need to make level adjustments at the
individual stations, the procedure which follows will provide uniform levels compatible
with most PA systems.
♦
To set Station Transponder Unit levels
1. At the FSA station, set the IP7 intercom Rx gain to mid range (using the two blue
buttons to step up and down):
a. Click the blue button
SW-2 (the one closer to the Ethernet connectors) six
times to go to minimum volume.
b. Click the other blue button SW-1 three times to select medium volume for the
PA.
2. At the FSA stations set the 1-turn pots R87 and R137 to mid range.
3. Set the radio console system output gain so typical voice is 2.2 Vpp (0 dBm)
leaving the console.
4. At the IP-FSA server, set the Windows Control Panel sound mixer’s record settings
to Mic In and set the Mic In gain to half-way.
5. Make a connection from the radio dispatch console and check the voice audio level
from the console entering the Audio and Digital Input Interface (P/N 950-0690) at
the IP-FSA server. It should be 2.2 Vpp (0 dBm). For a 60% deviation sine wave
test tone, this would be a level of 0.77 Vrms. If the level is wrong (too low due to
long cables, etc.), re-adjust the radio dispatch console’s output until the level
entering the IP-FSA server’s Audio and Digital Input Interface is correct.
6. Check the voice audio level at the FSA station PA output pins, J3 pin 11 to J3 pin
9 . It should be 1.13 Vpp +/- 0.5 Vpp (-14.7 dBu rms +/- 3 dBu).
7. If the FSA station output level is too low, try adjusting the Mic In gain at the IP-
FSA server up (from 50% to 100%). Listen for added distortion as some sound
card inputs (like some motherboard audio) will distort when set above the 50%
level. The Zetron-supplied sound card requires a 100%
Mic In gain setting.
8. If increasing the Mic In gain caused audio distortion, set the IP-FSA server Mic In
gain back down to 50% and try adjusting the FSA station PA IP intercom gain up.
This can be done by pressing the blue buttons on the IP7. The button closer to the
Ethernet jacks (
SW-2 ) steps the gain down, the other button ( SW-1 ) steps the gain
up. There are seven IP intercom gain levels. If the IP Intercom gain is set too high
the background noise may become objectionable.
Note The following procedure assumes two things: 1) the VoIP Server
levels have been set, and 2) that there is an external PA amplifier
between the Station Transponder Unit and the loud speakers in the
station.