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Before you make a call, you should set up the identity of the test
set and of the radio you want to call, to avoid calling anyone else
on the system. The test set has default values for group and log-
ical identities of 1.
The radio parameters set-up screen.
Press the [SET-UP] soft key until the screen above appears. The
radio logical ID is the identity of the radio the test set will call. The
IFR ID is the identity that the test set will use when it makes or
responds to calls. The group identity is both the group that the test
set will call, and the group identity that it will respond to.
If you now go back to the Manual test screen, and select [mode],
[individ call] the test set will attempt to make a call to the radio
whose identity is in the RADIO LOGICAL ID field. The mode
should change to WC CONFIRMATION, and then to WORKING
CHANNEL.
The MANUAL TEST screen after a successful individual call.
Selecting [mode], [clear down] will return the test set to the con-
trol channel.
You should now have a working EDACS repeater test system,
ready to go! The system parameters are stored internally in non-
volatile memory, but you may also like to take this opportunity to
save the settings on to a PCMCIA memory card.
Measuring off-air
The IFR 2945B test set has several tests built in to allow monitor-
ing and diagnosis of EDACS repeaters. These are designed to be
used off-air, and on a live system, so that the condition of the
repeater can be continuously monitored, without disrupting the
system traffic, as well as being connected physically to the
repeater RF and audio connections.
Distortion measurements can be performed on a channel with-
out requiring audio access to that channel. Three different dis-
tortion measurements are available - SINAD, signal to noise and
distortion, which should not be used in isolation. The values
returned by these tests should be used to detect degradation in
performance, with relative results being important, and not the
absolute values.
Data deviation tests are provided for both low and high speed
data, with the tests using advanced DSP (Digital Signal Processor)
filtering.
A data performance test is also provided, to allow the receiver on
the control channel to be tested.
All of these tests have test limits and parameters stored in mem-
ory so that you can tailor the test and the limits to your particular
system. The parameters are set up using the AUTORUN PARA-
METERS screen.
Additionally, one of the built in test programs, the QUICK TEST, is
designed specifically for use off-air.
The AUTORUN PARAMETERS set-up screen.
As an example, in order to set up the Quick test, we need to alter
the RF generator levels for all the signalling tests, and set the data
deviations to those in use on the system.
1) Set the RF GEN LEVEL to be +5 dBm for the:
CALL FROM IFR,
CLEAR FROM IFR and
DATA PERFORMANCE tests.
2) To do this, use either the up and down arrow keys, or the rotary
control.
3) Highlight the test required (the DATA PERFORMANCE test in
this example).
4) Now press [select] and a list of the test’s parameters is given.
5) Select the RF GEN LEVEL entry, and press 5.
6)
Then press either the [dBm] softkey, or the orange
[dBm/ENTER].
7) Pressing [return] returns you to the list of tests.
You should also set up the data deviations initially with either a
generous error tolerance (say 30%) or the known correct values
for your system.
Finally, the Tx LEVEL test is of little use in off-air measurement, and
should be turned off. The problem is caused mainly by the vari-
ability of the environment around the antenna (people, vehicles,
and buildings appearing between the antenna and the repeater),