Mocomtech CDM-QX Config„Tx Transmit, Tx FEC Mod Code Data Freq On/Off Pwr Scram Clk Inv Txα

CDM-Qx Satellite Modem	Revision 5
Front Panel Operation	MN/CDMQx.IOM

5.6.1.2(Config„Tx) - TRANSMIT

Tx: FEC Mod Code Data Freq

On/Off Pwr Scram Clk Inv Txα

Select FEC, Mod, Code, Data, Freq, On/Off, Pwr, Scram, Clk, Inv, or Txα using the ◄ ► arrow keys, then press ENT. The user will then be taken to a further sub- menu. Each of these choices is described briefly in the table below:

FEC

Mod

Code

Data

Freq

On/Off

Pwr

Scram

Clk

Inv

Txα

(Forward Error Correction) This sub-menu permits the user to select the method of FEC used for transmission (Viterbi, TPC, etc). FEC type takes the highest configuration priority.

(Modulation) This sub-menu permits the user to select the modulation type used for transmission (BPSK, QPSK, 8-PSK, etc.). The available choice of modulation will depend on the FEC type chosen.

(FEC Code Rate) This sub-menu permits the user to select the FEC Code Rate used for transmission (Rate 1/2, Rate 3/4, etc). The available choice of Code Rate will depend on both the FEC type and Modulation type selected.

(Data Rate) This sub-menu permits the user to select the transmit data rate, in steps of 1 bps. The choice of data rate will depend on the FEC type, Modulation type, and Code Rate selected.

(Frequency) This sub-menu permits the user to select the transmit frequency, from 950 MHz to 1950 MHz, in steps of 100Hz for L-Band units, or from 50 MHz to 90 MHz and from 100 MHz to 180 MHz for 70/140MHz units.

This sub-menu permits the user to control the output state of the transmit carrier.

(Output Power level) This sub-menu permits the user to control the output level of transmit carrier, either manually, or using the AUPC (Automatic Uplink Power Control) feature.

(Scrambler) This sub-menu permits the user to select whether or not data scrambling is used.

(Clock Source) This sub-menu permits the user to select the clock source for transmission. This can be from the internal source, from an external source, or from the distant-end of the satellite link (loop timed).

(Inversion) This sub-menu permits the user to invert the sense of the transmitted spectrum, or to invert the sense of the transmitted baseband data or data clock

(α-Factor) This permits the user to select the modulator’s roll-off factor either 20% or 35%.

The FEC type takes the highest configuration priority, and the selection here depends on what, if any, optional plug-in Codecs are installed. The choice of FEC type then determines what modulation types, code rates, and data rates

IMPORTANT are available. The order of hierarchy is therefore:
FEC type	► Modulation type ► Code Rate ►	Data Rate
(Highest)		(Lowest)

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