Motorola SSETM 5000 service manual Transmit Deviation Balance Alignment

Radio Alignment Procedures: Transmitter Alignments 5-7

5.5.4Transmit Deviation Balance Alignment

This alignment procedure balances the modulation contributions of the low- and high-frequency portions of a baseband signal. Proper alignment is critical to the operation of signalling schemes that have very low frequency components (for example, PL) and could result in distorted waveforms if improperly adjusted.

This procedure needs to be performed at multiple frequencies to allow for proper alignment across the entire RF band. The RF band is divided into frequency zones with a calibration point (value) in each zone.

NOTE: This alignment is required after replacing (or servicing) the VOCON board or the transceiver board.

To align transmit deviation balance:

1.Select the TX Deviation Balance alignment screen. The screen indicates the transmit frequencies to be used. See Figure 5-8 on page 5-7.

2.Left-click the desired frequency field (starting with the highest frequency shown).

3.Left-click the PTT Toggle button on the screen to make the radio transmit. The screen indicates whether the radio is transmitting.

4.Left-click the PTT Tone: Low button.

5.Measure the transmitted signal deviation of the radio with your communications system analyzer.

6.Left-click the PTT Tone: High button.

7.Adjust the softpot value until the measured deviation, when using the High Tone, is as close as possible to that observed when using the Low Tone.

Figure 5-8. Transmit Deviation Balance Alignment Screen

6881094C12-A November 11, 2004