Fine Tuning the Frequency Calibration Of PowerSDR

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Fine Tuning the Frequency Calibration Of PowerSDR


Fine Tuning the Frequency Calibration Of PowerSDR

System Dependencies
Minimum PowerSDR Version:
1.6.0
Applicable Hardware: All transceivers 

Content provided by: FlexRadio Systems Engineering

The frequency accuracy calibration process for the all FlexRadio software defined radios will produce a very close and accurate result due to the high stability XO. The SDR-1000, due to it's non-temperature controlled XO and DDS will require more frequent frequency calibrations. All frequency calibrations are controlled by PowerSDR.

These fine tuning methods are used after you have run the Frequency calibration routine in PowerSDR.

If you want to fine tune the frequency accuracy, then follow any of the procedures listed below.

NOTE: Please allow the SDR hardware to come to a stable temperature (>30 minutes for the SDR-1000)

Method 1 - DSB Mode + Phase Display
  1. Using the Setup program tuning calibration routine on the General-> Calibration tab, tune to a strong WWV station and calibrate. This will get you very close to start with.
  2. Place the PowerSDR display into Phase mode.
  3. Place the software defined radio into DSB mode
  4. Open the Setup program and access the General->Hardware Config tab. On the display you will see a signal that is rotating either clockwise or counter clockwise in a circle. Using the DDS adjustments change the DDS Clock Offset values either up or down by increments of 1 until you slow the rotation of this signal.
  5. Change the value of the DDS Clock Offset manually until you get a value that makes the signal stand still or the difference between two values makes the signal go one direction and then the other.

Method 2 - DSB Mode + Audible Zero Beat
  1. Using the Setup program tuning calibration routine on the General-> Calibration tab, tune to a strong WWV station and calibrate. This will get you very close to start with.
  2. Place the software defined radio into DSB mode
  3. Open the Setup program and access the General->Hardware Config tab. Using the DDS adjustments change the DDS Clock Offset values either up or down by increments of 1 until until you can hear the zero beat of the audio tones that WWV transmits.

Method 3 - DSB Mode + Scope Display

  1. Using the Setup program tuning calibration routine on the General-> Calibration tab, tune to a strong WWV station and calibrate. This will get you very close in frequency.
  2. Place the PowerSDR display into Scope mode.
  3. Open the Setup program  and access the Display tab.  Change the Time base in Scope Mode to 10,000 us.
  4. Place the software defined radio into DSB mode
  5. Open the Setup program and access the General->Hardware Config tab. On the display you will see a sine wave  traversing the screen. Using the DDS adjustments change the DDS Clock Offset values either up or down by increments of 1 until the period or the number of sine waves you see are at a minimum.  Ideally, it will be a flat line indicating that the phase of both sidebands are equal.


This KB article may reference additional files that are available on the FlexRadio Systems web site Downloads page. Please use the URL(s) below to download the referenced materials.

An Adobe Acrobat Reader may be required to open the file. You can download Adobe Acrobat from here.

KB Source Document(s):

None Referenced



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Last Modified:Wednesday, March 31, 2010
Last Modified By: Administrator
Type: HOWTO
Rated 5 stars based on 1 vote
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