adrv9002 LO change is very slow

In Vivado the ARM SPI clock is set to 187.5MHz, so this should be fast.
I am not sure if the driver sets the clock to a slower frequency?

Thanks

You are not bound by SPI here. When changing the LO by 100 MHz from an original point the part must be recalibrated. This can take some time. See page 86 of the user guide.

-Travis

Hi Travis,

Thanks for the response.
I tried to disable the calibrations: automatic gain control (RX_AGC), baseband DC offset (RX_BBDC), (2nd order) harmonic distortion (RX_HD2), frequency independent QEC (RX_QEC_FIC) and frequency dependent QEC for WB (RX_QEC_WBPOLY).

However, tuning still takes 200mS.

Can I turn off some other calibrations to speed this up?
I realize there may be some error in the data due to not being calibrated.

However, I would still like to do this.

Thanks

Hi Travis,

Thanks for the response.
I tried to disable the calibrations: automatic gain control (RX_AGC), baseband DC offset (RX_BBDC), (2nd order) harmonic distortion (RX_HD2), frequency independent QEC (RX_QEC_FIC) and frequency dependent QEC for WB (RX_QEC_WBPOLY).

However, tuning still takes 200mS.

Can I turn off some other calibrations to speed this up?
I realize there may be some error in the data due to not being calibrated.

However, I would still like to do this.

Thanks

You cannot disable this calibration since the PLL driving the mixer will not lock.

The only alternative is to use fast hopping but this is not supported in the Linux driver yet.

-Travis

Thanks Travis,

Is there an estimated time when fast hopping will be supported in the driver?

Changing LOs can indeed take some time.. On top of having to re-lock the PLL, the port also has to be moved to the calibrated state and then back to rf_enabled. Moving it back to rf_enabled can also take some time but way less than the 200ms (+/- 5ms; can also depend on the loaded profile). As Travis said, the only alternative is fast hoping but unfortunately, I still don't have an estimation on when it will be supported...

- Nuno Sá

Hello Nuno,

When you stated the PLL port has to be moved to the calibrated state, are you referring to in_voltage0_ensm_mode?

If not, what should I be changing when changing the LOs?

Is it fine just to change the RX1_LO and not the others, since I am just receiving?

As for the profile, I have set up 40M bandwidth and tried different sample rates ranging from 40.96M to 62,5M.

Is there a profile configuration that has a 40MHz bandwidth, that would tune faster, without the hopping?

Thanks very much

swie said:

When you stated the PLL port has to be moved to the calibrated state, are you referring to in_voltage0_ensm_mode?

Yes, but that is done by the driver under the hood so no need for you to do anything...

swie said:

Is it fine just to change the RX1_LO and not the others, since I am just receiving?

That's a tricky question as LOs are not obvious. Although in theory (assuming that you are only changing RX1_LOs and no other controls) only changing RX1_LO is fine. However, If you are using a FDD profile, it's best practice that you also change RX2_LO together with RX1_LO... If you prefer not to do it, then you should move in_voltage1_ensm_mode to calibrated before starting the RX1_LOs settings.

If the profile is TDD, for safety, you should TX1_LO to be the same as RX1_LO although this will only matter if you change a tracking calibration in RX1. Alternatively, on a TDD profile, you can just disable the TXs as you just want to receive.

This commit description explains the reasons behind this...

swie said:

Is there a profile configuration that has a 40MHz bandwidth, that would tune faster, without the hopping?

Don't think so...

- Nuno Sá

one more question...

Will TDD or TDM_FDD modes tune faster than FDD mode?

Not really sure as I never measured it. You can always try it

- Nuno Sá

The frequency hopping works on the TES software.
Since this is not supported in the driver yet, how does this work?

Is there different code on the Zynq Arm?

Is this code not using the meta-adi driver?

Thanks

There are API functions related to fast hopping modes that are specific to the transceiver. This API is used by the driver but the top level IIO driver does not expose them yet. You cannot access the API directly in Linux, but this can be done in No-OS where you only get the API not the driver.

The source API is available here: https://www.analog.com/en/design-center/landing-pages/001/transceiver-evaluation-software.html

When using the API directly you will need to manage state on your own.

TES also has specialized HDL to help demonstrate fast hopping, but you will need to ask in the TES forums about this IP and related software.

-Travis

I found that if I set the in_voltage0_ensm_mode to calibrated

Then tune the RX1_LO

The tune time is quite fast.

However, setting  in_voltage0_ensm_mode back to rf_enabled takes a long time.

Is there a parameter maybe in /sys/kernel/debug/iio that I can set to speed this up?

Also, I noticed that the pll_status is in the unlocked stated until I switch the ensm_mode back to rf_enabled. After that it reports locked.

Thanks again