Re: [Discuss-gnuradio] UHD Calibration continued.

[Josh Blum]

On 12/14/2011 01:55 PM, Evan Merewether wrote:
> I have been looking more at the performance of the udh_cal_* routines to try
> and understand the operation of my N210 and the SBX card.  I found the cal
> files that I had previously generated and moved them into a separate
> directory to prevent the UHD driver from finding them.  From the
> documentation, I think this should apply no corrections.  Then I removed the

correct

> antennas and terminated both inputs with 50 ohm terminators, running
> uhd_fft.grc with a frequency of 2.0087MHz (which is away from other spurious
> signals and near a calibration point), a sampling rate at 5M, a 2.048k FFT
> size, and an average of 0.004 produces a graph where I can observe both the
> average leakage power of the LO and the average noise floor.  This produced
> data for the LO [A - -99.21 dB, FFT: -106.14 dB] and noise [A: -117.138,
> FFT: -117.1 dB].
> 

So you are measuring the transmit LO leaking into receive? Which means
uhd_fft.grc is both transmitting and receiving?

> Can anyone tell me what mistake I am making?
> 
>  

The cal utilities are for suppressing IQ imbalance on RX and TX and DC
level on transmit. I dont know exactly what uhd_fft.grc is, but I dont
think you are measuring IQ suppression or TX DC level.

-Josh