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PSM-500/500L/500LT SCPC Satellite Modem
Installation
2.9.3 Sample Configuration Setting
The following procedures are used to set each of the modem's parameters using the front panel.
Assuming the modem is to be used in the SCPC mode for a point-to-point link with another PSM-
500, the following sample configuration is representative of the required procedures:
For easier entry we can first set the entry mode to "Quick". Go to <Unit: Keybrd – Entry> and
set the "Quick" mode. This is the default setting.
The desired transmit operating mode is 81.275 MHz, QPSK, 56 kbps, Rate 1/2 FEC, and receive
at 81.550 MHz, BPSK, 128 kbps, Rate 1/2 FEC. This example uses different transmit and receive
parameters to illustrate several points. The other end of the link would naturally have the opposite
transmit and receive parameter settings.
The transmit parameters will be set first. With the unit powered on, press the "Mod" function
button. Next, press the left or right arrow keys until the "IF" identifier is in the upper left line of the
LCD display indicating that we are in the Modulator IF column of the parameter matrix. Now scroll
down (or up) until the upper right of the LCD display indicates "Frequency". The value displayed
in the lower line is the current setting for the transmit frequency. A new frequency can now be
directly entered by using the numeric keypad. First indicate that a new entry is desired by
pressing the "Edit" key, which will display the current setting with the cursor set on the first
available digit. Enter a frequency in MHz not including the decimal point, entering all digits
required to specify the shown frequency, then press the "Enter" key to apply this new parameter
value. In this first setting we did not use the quick entry mode, but the following will use that
mode. Note that when not using quick entry the frequency edit function skipped over the decimal
point. Late you might try returning to the frequency setting and enter the frequency directly using
quick entry and the decimal point.
Next scroll down to the "Modulation" entry and press the "1" key to request QPSK, then press the
"Enter" key to apply this new parameter value. Scroll right to the "Data" column and down to the
"Bit Rate" parameter and press "56" and "Enter". (Without Quick entry we would have to press
"Edit", "0", "0", "5", "6" and "Enter". Note that if digits other than "0" had been set in positions after
the last "6" of the valid entry, then they must be overwritten with "0"s.) Last, scroll down to the
"Code Rate" parameter and press "Edit", "0" and "Enter".
To set the receive parameters, press the "Demod" button and the right arrow key until the "IF"
identifier is in the upper left line of the LCD display indicating that we are in the Demodulator IF
column of the parameter matrix. Now scroll down (or up) until the upper right of the LCD display
indicates "Frequency", and press the "Edit" key. Then edit the displayed frequency to 81.55 MHz
and press "Enter". Note that if digits other than "0" had been set in positions after the last "5" of
the valid entry, then they must be overwritten with "0"s. Scroll down to the "Modulation" entry and
press the "Edit", the "0" key to request BPSK and press the "Enter". Scroll right to the "Data"
column and down to the "Bit Rate" parameter and press "Edit", "0", "1", "2", "8" and "Enter". Last
scroll down to the "Code Rate" parameter and press "Edit", "0" and "Enter". Next scroll left and
down in the IF list to the "Sweep Range" parameter and set the value to 30 kHz.
This configuration example has illustrated how to "navigate" through the available parameter
matrix and has shown two modes of entry for numerical and list selected values. If the Unit
keyboard Entry had been set to "Quick" then all of the parameters shown above could have been
set directly without pressing the "Edit" key first. This mode also does not require that existing
characters be overwritten when entering new data.
Using the front panel or terminal command mode, set all modem parameters as necessary for the
type of service intended. This should prepare the unit for operation. If the modem is to be
controlled by an external command controller, set the modem address properly as described in
the next section. The modem should now be ready for service in an operating satellite system.
PSM-500/500L/500LT - Rev. 0.91
Page 2-19
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