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[Technical article / FAQ, rfforum Editorial Team]
LEO UT uplink ACLR is often frozen on a CW or static two-tone bench. On orbit-relevant links, Doppler ramp, power-control steps, and antenna-scan VSWR pull the PA through memory and supply sag that a static ACLR plot never sees.
1. What motion and control actually do
- Doppler and frequency-hop style retunes move the PA through bias and matching regions where ACLR and opposite-channel noise change
- Fast uplink power control can look like envelope steps; supply and thermal loops that were quiet on CW become ACLR contributors
- Scan-related antenna VSWR pulls the load line; a PA that passed into 50 Ω can fail into a real UT antenna at scan edge
2. Freeze list for a UT uplink ACLR claim
- Test waveform (CW vs representative modulation), Doppler / retune profile, and power-control step size on the same sheet as ACLR
- Antenna or load-pull VSWR profile used, not only 50 Ω
- Supply headroom and DPD / memory correction state during the dynamic test
- Whether the limit is per-carrier or aggregated across beams / carriers as the network will count it
3. Habit
Do not freeze "UT ACLR pass" from CW alone when the product must track Doppler and power control. Archive the dynamic profile next to the plot.
Discussion: on your last LEO UT ACLR surprise, did the fail appear under Doppler ramp, power-control steps, or antenna VSWR — and do you require a dynamic profile before accepting a CW pass?
— rfforum 编辑部 / Editorial Team
LEO UT uplink ACLR is often frozen on a CW or static two-tone bench. On orbit-relevant links, Doppler ramp, power-control steps, and antenna-scan VSWR pull the PA through memory and supply sag that a static ACLR plot never sees.
1. What motion and control actually do
- Doppler and frequency-hop style retunes move the PA through bias and matching regions where ACLR and opposite-channel noise change
- Fast uplink power control can look like envelope steps; supply and thermal loops that were quiet on CW become ACLR contributors
- Scan-related antenna VSWR pulls the load line; a PA that passed into 50 Ω can fail into a real UT antenna at scan edge
2. Freeze list for a UT uplink ACLR claim
- Test waveform (CW vs representative modulation), Doppler / retune profile, and power-control step size on the same sheet as ACLR
- Antenna or load-pull VSWR profile used, not only 50 Ω
- Supply headroom and DPD / memory correction state during the dynamic test
- Whether the limit is per-carrier or aggregated across beams / carriers as the network will count it
3. Habit
Do not freeze "UT ACLR pass" from CW alone when the product must track Doppler and power control. Archive the dynamic profile next to the plot.
Discussion: on your last LEO UT ACLR surprise, did the fail appear under Doppler ramp, power-control steps, or antenna VSWR — and do you require a dynamic profile before accepting a CW pass?
— rfforum 编辑部 / Editorial Team
