LimeSDR Mini Calibration Behaviour
Posted: Sat Jun 06, 2020 11:20 am
Jen G4HIZ has pointed out that when the LimeSDR is set to "Calibrate if Needed" or "Never Calibrate" (on Menu 3, Lime Config) on Portsdown Buster, the Lime does not always transmit correctly.
My tests show that if the LimeSDR has been powered down since the last stored calibration, it will not use the stored calibration even if asked to. I think that it is a problem with the initialisation sequence for the LimeSDR in the Portsdown, because if a calibration is subsequently performed, it will then quite happily use that calibration.
I do not intend to investigate this problem further for a few weeks; I have other priorities. In the meantime, I suggest that all users use the default "Calibrate Every TX" setting and make sure to use the delayed PTT available on GPIO pin 40 so that they do not transmit the calibration spike or damage their PAs.
Thanks to Jen for spotting the problem.
Dave, G8GKQ
My tests show that if the LimeSDR has been powered down since the last stored calibration, it will not use the stored calibration even if asked to. I think that it is a problem with the initialisation sequence for the LimeSDR in the Portsdown, because if a calibration is subsequently performed, it will then quite happily use that calibration.
I do not intend to investigate this problem further for a few weeks; I have other priorities. In the meantime, I suggest that all users use the default "Calibrate Every TX" setting and make sure to use the delayed PTT available on GPIO pin 40 so that they do not transmit the calibration spike or damage their PAs.
Thanks to Jen for spotting the problem.
Dave, G8GKQ