ACCURATE ELECTRONICS INC
Practice Section 104001C Rev B January 2014
PO BOX 1654 97075-1654 8687 SW HALL BLVD 97008 BEAVERTON OR USA 503.641.0118 FAX 503.646.3903
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6
Transmit Channel:
8.
Set all front-panel XMT LEVEL DIP switches for zero gain or loss,
i.e., to the OUT position.
9.
Arrange the transmit portion of the TMS for 1004Hz tone output at
the CLR-specified transmit input level and for the terminal side
impedance selected on the module (see note above), and connect it to
the module’s XMT IN jack.
10. Request personnel at the distant (facility-side) end of the circuit to
measure and report the level of the received 1004Hz tone.
11. Determine the difference between the actual received level at the
distant end and the desired level at that end.
12. Depending upon whether gain or loss is required to achieve the
desired level at the distant end (as determined in the preceding step),
set the module’s front-panel XMT GAIN/LOSS switch to GAIN or
LOSS as appropriate.
13. Set to IN that combination of front-panel XMT LEVEL DIP switches
which adds up to the difference determined in step 11, as verified by
a proper receive input level at the distant end of the circuit.
Equalization Adjustment
3.14
To adjust the 4001’s receive and transmit active slope equalizers when
prescription equalization settings (i.e., the amount of equalized gain at
2804Hz re 1004Hz required for each channel) are given in the CLR, simply
set the module’s front panel RCV EQL and XMT EQL DIP switches
appropriately, as directed in paragraph 3.015. If, however, prescription
equalization settings are not given in the CLR or if the given settings do not
provide adequate results, it is necessary to perform equalization adjustment
as directed in paragraphs 3.016 through 3.018.
Prescription Receive and Transmit Equalization
3.15
Equalization is introduced via the front –panel RCV EQL and XMT
EQL DIP switches. The specific amount of equalized gain at 2804Hz (re
1004Hz) introduced via each individual DIP-switch position is indicated on
the front panel adjacent to the switch. These switch positions are cumulative;
the total amount of equalized gain (0 to 7.5dB) introduced into a channel is
the sum of that channel’s DIP-switch positions set to in. Because the amounts
of required equalization given in the CLR may be specified to the nearest
0.1dB (while the RCV EQL and XMT EQL IP switches are arranged in 0.5dB
increments), use the following guidelines for rounding up or down when
setting the switches: If, for example, 0.3 to 0.7dB of equalized gain is
required, set the switches to introduce 0.5dB. If 0.8 to 1.2dB of equalized
gain is required, set the switches to introduce 1dB. Similarly, if 1.3 to 1.7dB
of equalized gain is required, set the switches to introduce 1.5dB, and so on
upward through the switches’ range. If no equalization is required for a
channel, ensure that all of that channel’s equal DIP-switch positions are set
to out.
Non-Prescription Receive-Channel Post-Equalization Adjustment.
3.16
To determine the need for receive-channel post-equalization at the local
end of the facility, and to adjust the module’s receive equalizer when
prescription settings are not given in the CLR, proceed as follows:
1.
Ensure that all front-panel RCV EQL, DIP-switch positions are set to
OUT for no equalization. Then remove the module from its mounting
position, ensure that both terminating-impedance switches (S1 and
S3) are correctly set, and reinsert the module into its mounting
position.
2.
Arrange the receive portion of a transmission measuring set (TMS)
for terminated measurement at the terminal-side interface impedance
selected on the module. Connect the receive portion of the TMS to
the module’s RCV OUT jack. (The transmit portion of the TMS must
remain disconnected from the module at this time.)
Note: If the TMS does not provide and impedance setting that matches the
impedance selected on the module, re-option the module as necessary for a
proper impedance match during this procedure. Then, when this procedure
is completed, reset the module’s impedance as required.
3.
Have the distant facility-side end send 1004Hz test tone at the CLR-
specified level. Verify that the TMS reading equals the CLR-
specified receive level; then measure and record the level.
4.
Now have the distant facility-side end send 2804Hz test tone at the
CLR-specified level. Measure and record the received 2804Hz tone
level. Subtract this 2804Hz level from the 1004Hz level measured in
step C.
5.
Set to IN the proper combination of RCV EQL DIP switches that
approximates as closely as possible the measured difference, i.e., the
amount of equalized gain required, as specified in Table 4.
Non-Prescription Transmit-Channel Post-Equalization for
Intermediate Applications.
3.17
In intermediate-repeater applications, transmit-channel equalization is
often used to post-equalize the input to the module’s transmit channel in the
same manner as the module’s receive equalizer. In such applications, to
determine the need for transmit-channel post-equalization at the local end of
the facility interfacing the module’s “terminal” side, and to adjust the
module’s transmit equalizer when prescription settings are not given in the
CLR, proceed as follows:
1.
Ensure that all front-panel XMT EQL DIP-switch positions are set to
OUT for no equalization. Then remove the module from its mounting
position, ensure that both terminating-impedance switches (S1 and
S3) are correctly set, and reinsert the module into its mounting
position.
2.
Arrange the receive portion of a transmission measuring set (TMS)
for terminated measurement at the facility-side interface impedance
selected on the module. Connect the receive portion of the TMS to
the module’s XMT OUT jack. (The transmit portion of the TMS
must remain disconnected from the module at this time.)
Note: If the TMS does not provide and impedance setting that matches the
impedance selected on the module, re-option the modules as necessary for a
proper impedance match during this procedure. Then, when this procedure
is completed, reset the module’s impedance as required.
3.
Have the distant terminal-side end send 1004Hz test tone at the CLR-
specified level. Verify that the TMS reading equals the CLR-
specified receive level; then measure and record the level.
4.
Now have the distant terminal-side end send 2804Hz test tone at the
CLR-specified level. Measure and record the received 2804Hz tone
level. Subtract this 2804Hz level from the 1004Hz level measured in
step 3.
5.
Set to IN the proper combination of RCV EQL DIP switches that
approximates as closely as possible the measured difference, i.e., the
amount of equalized gain required, as specified in Table 4.
Non-Prescription Transmit-Channel Pre-Equalization for Terminal or
Intermediate Applications.
3.18
In both terminal and intermediate repeater applications, transmit-
channel equalization (i.e., pre-equalization) at the local end of the facility is
normally left flat (no equalization) in favor of receive-channel post-
equalization at the distant end of the facility. In such applications, to
determine the need for transmit-channel pre-equalization, and to adjust the
module’s transmit equalizer when prescription settings are not given in the
CLR, proceed as follows:
1.
Ensured that all front-panel XMT EQL DIP switches are set to OUT
for no equalization. If you have not already done so, remove the
module from its mounting position, ensure that both terminating-
impedance switches (S1 and S3) are correctly set, and reinsert the
module into its mounting position.
2.
Connect the transmit portion of the TMS, arranged for the terminal-
side interface impedance selected on the module, to the module’s
XMT IN jack.