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#1 2007-May-04 10:12:23

From: Vienna, VA
Registered: 2007-Jan-24
Posts: 121

Radio Card Calibration and Initialization

Q1) Do we need to perform receiver and transmitter IQ Gain and Phase Imbalance Calibration? Or it had been calibrated before the radio card is shipped?

Q2) Have you ever run into a situation that you need include a digital I/Q imbalance correction block in FPGA logic?

Q3) In the warpmac_init(), there is a function call --- warpmac_CalibrateTxDCO() -- What is this for? Is this function already included in the WarpRadio_v1_Reset()?

Q4) Is it possible to list all the default status after calling WarpRadio_v1_Reset()? Such as the LPF bandwidth, the corner frequency, Tx and Rx gain control mechnism, TxTiming and TxGainTiming, etc. It is my understanding that we only need to call WarpRadio_v1_Reseat() to set everything to default values. If no need to change the default values, we can just go ahead to send and receive data. Am I right?

Q5) In the OFDM reference design V2, I notice the following two lines


WarpRadio_SetTxTiming(XPAR_RADIO_CONTROLLER_0_BASEADDR, FIRST_RADIO, 50, 0, 0, 0); //radio 2
WarpRadio_SetTxTiming(XPAR_RADIO_CONTROLLER_0_BASEADDR, SECOND_RADIO, 76+50, 76, 76, 76); //radio 1

Why these values are different for different radio slot? Is this what we should be careful for MIMO implementation?

Thank you very much!



#2 2007-May-04 20:10:12

From: Mango Communications
Registered: 2006-Jul-03
Posts: 5159

Re: Radio Card Calibration and Initialization

1-2) It is possible to calibrate I/Q phase & gain imbalance, but we've found that the radios don't really need it. The MAX2829 datasheet backs this up (see pg. 4 for the specifics).

3) This is for reading Tx DC offset calibration values from the radio board's EEPROM. See WARP Radio Board TX DC Offset Calibration for more details.

4) The MAX2829's registers are write-only. A local copy of the current radio state is maintained by global variables in the radio controller driver. You can access these to view the current values of each radio register.

5) In radio controller versions up to 1.07, driver calls which control multiple radios accessed each radio sequentially. This was problematic for MIMO configurations, where you want multiple radios to function identically & simultaneously. The different timing values in these two function calls compensated for this. In radio controller 1.08, the hardware was redesigned so that each function (TxEnable, TxRxDisable, etc.) affects up to four radios simultaneously. We haven't posted an OFDM reference design with the 1.08 controller yet; we will soon.



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