User's Manual

Page 48
E Series Data Radio – User Manual
© Copyright 2005 Trio DataCom Pty. Ltd.
There are two methods for setting the power.
• Using Factory Calibration
To use the factory calibration of the radio the desired power
is set immediately using the OK button in the dialogue box.
This method permits the transmit power to be set without
energising the transmitter. Note that although the transmit
power has been adjusted it must be written to NVRAM using
the modem “Write” function to ensure it is retained after a
power on reset.
• Using a Power Meter
To overcome manufacturing variations in the power setting
a more accurate setting of power can be achieved by the
selecting the “Test With Meter” button in the dialogue box.
This displays another dialogue box warning the user that the
transmitter is about to be energised and that the power meter
used should be able to handle at least 10 Watts from the
modem.
Selecting OK in this warning dialogue box will energise the
transmitter which will also be indicated by the red transmit
LED on the unit. The power is adjusted using the up/down
keys until the required power level is obtained. Selecting OK
will retain the power setting and turn the transmitter off.
Note: Although the transmit power has been adjusted it must
be written to NVRAM using the modem “Write” function to
ensure it is retained after the modem is rebooted.
Selecting “stop test” will stop and leave you in power adjust
box. “Cancel” will stop test and take you back to the main
window.
Receiver
The receiver can be configured for receive frequency and mute
level.
Frequency
The required receive frequency in MHz can be entered in the
display field. The programmer checks that the selected frequency
is in the range for the particular model of radio and provides
warnings if not.
Mute Adjust
The currently selected mute level is displayed in the main window
below the button in dBm. The mute level can be adjusted by
selecting this button which displays a dialogue box. The up/down
keys, or a typed in value, can be used to select the required mute
level in dBm steps. Whilst a session is in progress with a unit the
mute level adjustment is live. Selecting OK will retain the mute
level setting. Note that although the mute level has been adjusted
it must be written to NVRAM using the modem “Write” function to
ensure it is retained after the modem is rebooted.
Whilst the modem is capable of receiving extremely weak radio
signals, and successfully extracting the data content from the
waveforms the mute level should be set to assist the modem in
filtering out unwanted signals. Unwanted signals can be the result
of background noise or interference. The mute level should be set
at a level above these unwanted signals and at a level low enough
to detect the wanted signal. Detection of a received signal above
the mute level is indicated by the “RxSig” LED on the unit.
Setting of a correct mute level at a base station is critical if collision
avoidance is operational in a point to multipoint system. In this
situation detection of “noise” instead of a valid transmission from
the remote modems will effectively “lock out” all of the remote units
from accessing and using the channel.
Due to normal manufacturing variations the actual mute level
may vary by several dBm to that selected. If a more accurate
adjustment is required an unmodulated signal of the correct
frequency and desired threshold level can be applied to the radio
modem’s antenna connector.
Modulation
The radio modem utilises a DSP to control the modulation of
transmit signals and de-modulation of received signals. This
provides greater flexibility in the ability of the radio modem to
support new modulation schemes whilst maintaining compatibility
with existing modulation schemes.
The currently selected modulation scheme is displayed in the main
window below the select button. The modulation scheme can be
adjusted by selecting this button which displays a dialogue box.
The desired modulation scheme can then be selected from the
pull-down menu in the dialogue box and retained using the OK
button.
In the case of 12.5kHz channel radio modems the presently
Part I – TVIEW+ Management Suite - Programmer