Chapter 17 615
W-CDMA Downlink Digital Modulation for Receiver Test
Setting Up for a Compressed Mode Signal
Setting the Compressed Mode Parameters
1. Press
Link Control > 5 > Enter > Compressed Mode Setup.
Notice that the cursor is already showing in the compressed mode table editor. This means you can
immediately start editing parameters upon entering the compressed mode display. This is unlike the
uplink where another softkey needs to be pressed before the cursor is displayed in the table editor.
The compressed mode feature is accessible only when the DPCH (5) is highlighted. The
Compressed
Mode Setup
softkey is grayed-out when any other channel is selected.
2. Set slot eight of the frame as the starting slot for the first transmission gap.
a. Move the cursor to highlight the TGSN field.
b. Press
8 > Enter.
This sets the first compressed frame to have eight slots (0–7) of data with slot eight marking the
beginning of the first transmission gap.
3. Set the first transmission gap length which is expressed as a number of slots.
a. Move the cursor to highlight the TGL1 field.
b. Press
14 > Enter.
Out of the 15 slots per frame, the standard specifies that seven of them can be used as discontinuous
transmission (DTX) slots. However the total gap length can be spread over two frames. The value 14
denotes 14 DTX slots, which spans 2 frames. This is called the double-frame method. When TGSN is ≤
8 and TGL is ≤ 7, then the DTX slots are contained in one frame forming the single-frame method.
4. Set the second transmission gap length which is expressed as a number of slots.
a. Move the cursor to highlight the TGL2 field.
b. Press
3 > Enter.
For the second transmission gap, the single frame method is used.
5. Set the spacing between the first and second transmission gaps expressed as a number of slots.
a. Move the cursor to highlight the TGD field.
b. Press
37 > Enter.
6. Set the duration of the first transmission gap pattern which is expressed as a number of frames.
a. Move the cursor to highlight the TGPL1 field.
b. Press
6 > Enter.
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