6700 Radio Setup WWV Calibration

  • 1
  • Problem
  • Updated 4 years ago
  • Acknowledged
  • (Edited)
Tim,

I am almost positive that I remember you indicating that the problem (no persistence) with the offset determined by calibrating against WWV would be fixed in the 1.3 release. It appears that this is not the case. It sure would be great if I did not have to re-calibrate each time that I powered on my 6700.

On a related issue, my radio requires approximately a -2500 ppb offset. That seems rather high... is it within specs?

Ed, K0KC
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Ed, K0KC

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Posted 4 years ago

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Tim - W4TME, Customer Experience Manager

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It was supposed to be fixed.  So if you run the calibration and validate you are on frequency (zero beat with WWV), shut down SmartSDR, power cycle the radio, start up SmartSDR and tune to WWV (15 MHz), is it (a) actually off frequency and (b)  the ppb offset indicator reads 0?

I can't test this because my radio has a GPS.
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Ed, K0KC

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Ok, Tim, I did the following:

I had previously calibrated (earlier this morning) the radio to WWV and the offset showed -2154.

I went to 15 MHz and noted that I was close to a zero beat with WWV.

I shut-down SmartSDR and power-cycled the radio and the when the radio booted-up, the panadapter showed that I was considerably off from a zero beat with WWV.

I then went to Radio Setup:Receive  and noted that the offset had been cleared to zero. I then did another calibration and my offset changed to -2089. I went back to 15 MHz and noted that I was close to a zero beat with WWV.

On  my 7600 at least, it seems like a power-cycle clears the offset value.

Ed, K0KC
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Tim - W4TME, Customer Experience Manager

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Ed - try resetting your persistence database (power off the radio, press and hold the OK button while momentarily pressing the power button.  Hold the OK button until the OLED display counts down to 0 and the Calibrating message is displayed with a flashing light purple power LED indicator).

Then do a frequency calibration, reboot and see if the value resets to 0
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Ed, K0KC

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I guess I just did not understand how the system works. When I re-booted the radio, I expected the offset to retain the previous value of about -2550 in my case. When I checked, the offset was indeed zero, but when I went to WWV, the radio appeared to be on frequency. I guess the problem was solved by the persistence database reset.

Ed, K0KC
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Tim - W4TME, Customer Experience Manager

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Ed - You understand correctly.  Thanks for doing that test.  It looks like the annunciator for the frequency offset is not being updated.  This is a bug and I have written it up as a defect for the engineering team to look at. 
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Al K0VM, Elmer

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Ed,
  The stability spec for the internal ref on the 6700 seems to say 0.02 ppm .. -2500 ppb would be 2.5 ppm...  My 6500, calibrates (WWV 10mhz) to -500 ppb ... 0.5ppm which is the spec for the 6500 internal ref.

AL, K0VM
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Martin Ewing AA6E

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Stability does not guarantee accuracy. I have found the reference can be off frequency by more than the 'stability' spec. It is easy to remove the offset with the rig setup dialog. I'm a little surprised that FRS doesn't set this at the factory. Maybe the setting is stored in SSDR?
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Ken - NM9P, Elmer

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It sounds like the lesson we had in High School Physics class about the difference between precision and accuracy.  Best illustrated by a target.  A precision shooter could place 6 shots within the space of a quarter (precision), but the quarter might be 4 inches off center and to the right (accuracy).  Whereas a more accurate, but less precise shooter may have all six shots within 2 inches of center, but scattered in all different directions.  The first shooter is more precise but less accurate.  The second shooter is more accurate, but less precise. 

Ken - NM9P