Frequency Offset, "offset (in ppb)

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  • Updated 3 years ago
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In the Radio Setup using 15Mhz I am now getting a reading of -684 ppb is this level acceptable?

Ian
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KM4CQG

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Posted 3 years ago

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Bob Brown - N8OB

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Mine runs at +480 and is correct.  The reading you are getting sounds like you are not seeing 15Mhz correctly.  Have you tried it on 10 Mhz?
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Greg - N8GD

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I don't know if the radio compensates for it or not, but I always try to do the calibration during the portion of the WWV signal when there's no tone modulation.  Listen to the signal before you run the calibration routine and find out when the tone is not there - the last 15 seconds of most minutes, if I recall correctly.  I also seem to have had better luck with 10 MHz even if the propagation favored the higher frequencies on a particular day or at a better time of day.

Last time I calibrated mine (a few months ago, after they fixed the problem with the calibration not working in SSDR), my 6300 has an offset of -127 at 15 MHz (looks like I don't follow my own frequency advice!).

Greg - N8GD
(Edited)
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Tim - W4TME, Customer Experience Manager

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We calibrate on the carrier, not the tone pulses.
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Bob Brown - N8OB

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If you use the calibration procedure on the radio, it takes the radio into 15Mhz or whatever freq you are using on WWV.  It will automatically adjust things correctly.
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George Molnar, KF2T, Elmer

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Yes, your value is well within acceptable limits. It will vary from measurement to measurement.
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David Decoons wo2x, Elmer

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my 6700 is consistently around -2300
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Lawrence Kellar KB5ZZB

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My 6700 is at -4000 ppb.  I have a help desk ticket opened for about a week waiting for an answer.  It is very stable though.  
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George Molnar, KF2T, Elmer

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This value is the correction applied to an internal component to bring the system to "exactly right." Whether or not it is a part per billion or 4 parts per million is not really important, as long as the value is relatively stable over time. A "large" value, as reported by Lawrence, for example, doesn't indicate a problem. It represents 8 Hertz correction (not error) at 30 MHz. If having a harmless value present makes you nervous, the GPSDO option may be for you.
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Lawrence Kellar KB5ZZB

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Thanks. All I needed to know was that it was ok. I just wanted to make sure it wasn't a symptom of a more serious problem I did learn however that you have to have your antenna connected to antenna one to calibrate. You cannot calibrate off of antenna two
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Lawrence Kellar KB5ZZB

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I just got word back from Flex. 4000 is out of spec and I will have to send my radio in. It looks like it is time for a nice leisurely drive to Austin. The last time I shipped the radio it cost me $120
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David Decoons wo2x, Elmer

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Did they say what is considered maximum? Mine is around 2300 consistently.

Dave wo2x
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Lawrence Kellar KB5ZZB

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No they did not.
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KM4CQG

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Gentleman

Thanks for all the info the past few months I have measured the WWV signal and have got a consistent -664 to -684 value.

Appreciate all the info as this feature other then how to use it doesn't mention a value that is acceptable.

Ian
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Tim - W4TME, Customer Experience Manager

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If the calculated value is out of range, an error occurs.  if you get a non- zero value, it is safe to assume that the test was successful.
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KM4CQG

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Thanks Tim
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Tim - W4TME, Customer Experience Manager

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The short answer is yes.  
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Rick WN2C

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Would you get different results using different offset frequencies for WWV?
I get slightly different results using different freqs from WWV. They all range from 128 to 118.
Just so I understand how this calibration works, it takes the offset and applies it to a device in the radio to correct it? And once applied it is exactly on frequency?
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Tim - W4TME, Customer Experience Manager

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Differences in atmospheric Doppler frequency shifting could account for it.

Once the calibration routine has run, the radio is on frequency within spec based on the frequency source using the offset calculated. 
(Edited)
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Gerald - K5SDR, Employee

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The answer is that if the frequency calibration function works and the frequency is stable your radio is operating properly.  It should always generate a non zero value it the routine has properly calibrated.  The stronger the calibration signal, the better the accuracy.  The higher the frequency of the calibration signal the higher the accuracy.  The absolute offset is not critical so long as calibration works properly.  Expect the values to change over time deviating further from zero due to normal aging.  

Gerald
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David Decoons wo2x, Elmer

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Thanks Gerald. Just making sure the 6700 is ok. I know after software upgrade you need to recalibrate.

Dave wo2x
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Ken - NM9P, Elmer

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OK, thanks, Tim.  That is good to know. 
(That was probably one of many things that changed along the line of the many updates over the past three years?)

I apparently have some other issue that is occasionally zeroing it out.  Perhaps changing between different clients, i.e. between SSDR, DL8MRE Radio App, (Alpha)  & K6TU's Remote.  I just assumed that it was zeroed out after an update or two. 

I might have done a persistence reboot somewhere along the line, also.  I seldom need to do that but I may have done it after a glitch and forgotten about it.

Ken - NM9P
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Tim - W4TME, Customer Experience Manager

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The only thing I am aware of in the code that would zero out the frequency cal offset data is if the radio thinks there is a GPSDO installed.
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Ken - NM9P, Elmer

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Hmmm. 

Does the CAL setting get saved in a Global Profile?
Could I have saved one with Calibration of zero, which would reset it to zero when I reload the global profile?

I am not near the rig to test it now, but now I am intrigued to solve this mystery.....(not a problem or an issue...just an unsolved mystery.)

It might have been zeroed out when attempting to calibrate from DL8MRE over a marginal connection that didn't finish the job, or perhaps a glitch in the Radio App, or a bad data file in it's settings......(at this point I don't even remember if the DL8MRE alpha has implemented the calibration routine.)

No biggie.  Just my problem-solver personality kicking in......ha..... "Something is afoot, my dear Watson!"
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Tim - W4TME, Customer Experience Manager

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No.  It is stored in the EEPROM with all of the other radio calibration data.
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David Decoons wo2x, Elmer

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I too have see the cal setting get zeroed out. It very well could be from bouncing back and forth between different clients (SSDR, Maestro, DL8MRE< K6TU, etc).

I hardly ever turn off the radio but when I did the other day I noticed the yellow light was staying on but I do not have the GPS option installed. I uninstalled the GPS from the radio setup and the light now goes off when powered down. This thinking the GPS is installed could have been the cause of the calibration getting reset to zero.

I will do some testing later today switching between clients to see if something is setting the radio into thinking the GPS is installed.

Dave wo2x
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PA2TA

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Just wondering, over here in Europe i get (very) different results for every attempt to calibrate my 6300. Which makes sense because WWV is far out of reach, i presume the radio does not switch to another standard signal for Europe?

SSDR v1.8.4.168
HW version v1.8.4.84

Tjakko PA2TA
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Tim - W4TME, Customer Experience Manager

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Tjakko,

I am aware of other time sources world-wide
http://www.dxinfocentre.com/time.htm

Just manually enter the frequency of one of them which is providing a strong signal into the calibration routine and use it.  Remember to press the Enter key after entering the new frequency.
(Edited)
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PA2TA

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Hi Tim,
Thanks for the response, at the moment the only usable station is RWM in Moscow on 4.996, it is abt S7 or -97dBm, the noise floor is at abt -100dBm. I still get very different results, varying from -12 up to +786, maybe the signal is not strong enough?

I will try some other freq's later, for now its time to call it a day.

Tjakko PA2TA
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Tim - W4TME, Customer Experience Manager

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An S7 signal with a low noise floor should be enough to calibrate, but in your case the SNR (signal to noise ratio) is not high enough to properly discern the carrier from the noise floor, which is causing the wide variations in the offset correction.