Warning with NIRFSG_ATTR_LO_IN_POWER attribute when setting the output of NI5673

[ilyak]

Hello:

I have a code that sets output power and frequency of NI PXI5673 generator. I used the example provided with the niRFSG library - RFSG Frequency Sweep.vi (attached). 

The spec for the generator says that it can generate continuous signals up to 6.6Ghz at power level of 0dBm. However, at about 5.6Ghz I get this warning from the driver:

Warning 1073366015 occurred at niRFSG Initiate.vi

Possible reason(s):

The specified value is outside the valid range. Device performance is not guaranteed.

Property: NIRFSG_ATTR_LO_IN_POWER

Requested Value:  0.000000

Value Must Be Less Than: -511.854359e-3

Warning 1073366015 occurred at niRFSG Initiate.vi
Possible reason(s):The specified value is outside the valid range. Device performance is not guaranteed.
Property: NIRFSG_ATTR_LO_IN_POWERRequested Value:  0.000000Value Must Be Less Than: -511.854359e-3

The help doesn't say anything about the limitations of RFSG_ATTR_LO_IN_POWER attribute.

1. Where can I find the spec for this parameter?
2. What are the implications of ignoring this warning?

Thanks so much,

-Ilya.

[chris_amadasun]

Hello IIya,

I ran the VI on a set up here using the PXIe-5673 (PXI-5652 for the LO), I did not encounter that error.

The set up I ran the VI has the NI-RFSG v 1.6.2 driver

Can you check to see what version of the driver you have and upgrade to 1.6.2 or 1.6.3?

Here a link to the NI-RGSG Drivers and Updates.

I hope this helps.

[ilyak]

Hi Christian:

I did the upgrade to 1.6.3, but the effect is still can be observed. You can use the vi attached.

There is, however, one caveat: I have three 5673 generators daisy-chained. The first one (the one connected first to the 5652 generator) works fine. I stepped through all the frequencies and no warning was observed. The next two generators still produce this warning. 

-Ilya.

PS: a side question - do you by any chance know anything about NIRFSG_ATTR_FGEN_SESSION attribute?

[chris_amadasun]

Hi Ilya

In that case you are using the PXIe-5673E with a shared LO?

Trying to replicate this on my end will take a while (I don't have all the neccessary hardware).

Coud you take an NI Spy capture and attach it to a reply to this post. Under View Selection please check the IviRFSigGen and NI-RFSG api choices.

Thanks you

[ilyak]

The SPY log is attached.

-Ilya.

[chris_amadasun]

Hi Ilya,

Could you redo the capture and save it as a Spy log that way I'll be able to open and analyze it in the NI-Spy environment?

Thanks

[ilyak]

It'a attached.

-Ilya.

[chris_amadasun]

Thanks Ilya, we are looking into this.

[chris_amadasun]

Hello Ilya

I have some further information for you.

The 5611 is the unit that repeats the LO and there is a bit of filtering that is done to the LO after it comes from the 5652, including some amplification, so if the amplitude out of the 5652 was slightly high, there is a possibility that the amplitude of the LO going to 5611 (2) and 5611 (3) could be slightly higher than the amplitude that the 5611 is expecting.

The other thing that I noticed is that the VI they attached only configures one of the 5450/5611 pairs along with the 5652. I don't see anywhere that indicates their configuration of the other two 5450/5611 pairs. Also, are they sure that they are daisy chaining the LO in the proper order? My understanding is that they would need to set up the two 5450/5611 pairs downstream in upconverter only mode.

Let me know how that works

[ilyak]

Hi Christian:

1. The generators are daisy chained together.
2. Do I have to configure all three pairs of 5450/5611 all the time? Is there any particular recommended order of this configuration?
3. The downstream devices are setup in the way that they receive LO properly (the signal is being generated correctly on the correct frequencies). This setup is done once in MAX.
4. Why does this warning only occur on one frequency?

-Ilya.