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How to Frequency Calibration on EU1KY Antenna Analyzer

How to Frequency Calibration on EU1KY Antenna Analyzer

I will calibrate the frequency of AA in two ways.
One is using the instrument and the other is using the SSB radio without the instrument.
To use an AA as a generator to test a radio, you must have a calibration procedure. 
Also To use the WSPR, FT8 generator included in Version 0.40, the frequency should not be too different.

1.How to calibrate using instruments
First, check the XTal frequency on your AA. Maybe it will be 27Mhz most like me.


In configuration, set Si5351_corr value to 0. Maybe this value will be 0 if you have not tried setting it yet.

Important here.
Does your instrument support XTAL frequency (27Mhz)? Then set 27Mhz.
(No need for a calculator.)

If the accuracy of your instrument is low? If so, set it to the maximum value that the instrument can receive. (ex : 50Mhz, 70Mhz)

The higher the frequency, the greater the error generation, so the less precise instrument can be quite accurate calibration.

I set it to 21Mhz to give an example. You can set it to any frequency.


Check the measured value of the instrument. 
In my case, measured frequency is 21.003314018Mhz
Calculate the difference between your AA frequency and the measured frequency.

Measured Frequency - AA (Generator) Frequency
In my case : 21003314 - 21000000 = 3314hz
I will call this value the error frequency.



In this part, you do not need this calculation part if you used 27Mhz. The values calculated above can be used as is. If you are bored, you can calculate it.

If you do not use 27Mhz (XTal Freq), calculate as follows.

(X-tal Frequency / RF Generator Frequency) * error frequency (Calculated just above, in my case 3324)

Below is an example of my case :
(27000000 / 21000000) * (21003314 - 21000000) = 4261.8 

My calibration value is 4261 (Round)

If you measured the frequency using 27Mhz, you would not need to calculate it because of the formula below.
(27Mhz / 27Mhz) * (error Frequency) = 1 * (error Frequency) = error Frequency


Enter the calculated calibration value in SI5351_CORR.
In Version 0.35 and later, a + - 200Hz button has been added to allow for faster input.

The two pictures below are in my case.

It can be seen that it is accurately set to less than 1 Hz.
However, the higher the frequency, the greater the error.

Test by increasing or decreasing the frequency by 1Hz.

Video



2.How to calibrate using SSB Transceiver with your cell phone
First, check the XTal frequency on your AA. Maybe it will be 27Mhz most like me.

In configuration, set Si5351_corr value to 0. Maybe this value will be 0 if you have not tried setting it yet.


Important here.
Does your SSB Transceiver support XTAL frequency (27Mhz)? Then set 27Mhz.
(No need for a calculator.)

Or you can use any frequency.
The higher the frequency, the greater the error generation, so the less precise instrument can be quite accurate calibration.

I set it to Xtal Frequency (27Mhz) to give an example. You can set it to any frequency.

in RF Generator -> Touch Frequency Button -> Input Frequency 

Now your AA is generating radio waves.

Please use the radio to receive radio waves from AA. 
USB mode is recommended. LSB does not matter, but the method of calculation is slightly different.


When you start to hear the sound, take your cell phone out.

Your phone must have an app that can view Spectrum. It is mostly free.
This app shows the spectrum of notes coming through the microphone.

That kind of app is on both Iphone and Android. It does not matter if you like what you like.

I use an app called spectroid.

Try adjusting the frequency of the transceiver until the sound from the transceiver is 1 kHz.





I set it to 1Khz.

Now check the frequency of the radio.
In my case : 27.003260 Mhz

Please subtract the frequency of AA from the frequency displayed on the transceiver.
In my case : 27003260 - 27000000 = 3260
Add 1000 to the above value.
In my case : 3260 + 1000 = 4260 (error Frequency)

If you were using 27Mhz like me, the following calculation is not necessary. The error frequency shown above is your calibration vlalue.


If you do not use 27Mhz (XTal Freq), calculate as follows.

(X-tal Frequency / RF Generator Frequency) * error frequency (Calculated just above, in my case 3324)

Example)
If your frequency was 50Mhz, it would have been calculated as follows. :
(27000000 / 50000000) * (4260) = 2300 (Your calibration value)

If you measured the frequency using 27Mhz, you would not need to calculate it because of the formula below.
(27Mhz / 27Mhz) * (error Frequency) = 1 * (error Frequency) = error Frequency



Test by increasing or decreasing the frequency by 1Hz.

Video




3. conclusion
I had previously posted the Si5351 calibration method on the uBITX (QRP transceiver).

If use the method of correcting the PLL frequency of DDS, it will be more accurate calibration. I will fix the firmware for Calibration later if I need more accurate frequency than AA.
But this is quite useful for making or repairing a transceiver.


Thanks for reading
Ian KD8CEC

Comments

  1. This comment has been removed by the author.

    ReplyDelete
  2. Dear Ian, Thanks for sharing your nice software of the analyser. I do have one question about your determening method for the correction value via the SSB receiver. Maybe I am wrong but without questioning I never know. So I thought when you listen in USB the carrier is down to the audio. When I receive the 1 khz. tone in the audio spectrum exactly as you discribed, it means that the carrier is 1 khz. under that point. So when the reading is 27.003.260 the carrier is on 27.002.260. So the correction value is then 2.260 and should be not plus but minus because in my opinon the software has to - in this case - correct the higher transmitting generator. In my case - by the way - I receive 1 khz in USB on 26.998.960. In theorie the correction is then 1040 + 1000 = 2040 plus because the software has to correct the lower transmitting generator. Perhaps I make a big mistake but I hope you can respond so I understand it. Thanks for all...Edwin the PA7EW from Holland.

    ReplyDelete
    Replies
    1. PA7EW

      Did you have good weekend?
      Thank you for sharing a good question.

      USB converts frequencies greater than the base frequency to audible frequencies.
      So we call it Upper SideBand.
      I could not attach a picture to the Comment, so I tried to draw it as shown below.

      |
      |-------------------> -------->
      |
      -----------------------------------
      27Mhz 27.0005 27.0010 27.0020
      USB (Receiver)

      As shown above, USB receives above the reference frequency (the Carry frequency of the receiver). (Upper Side Band)

      At this time, if the accurate signal generator generates a signal with 27.001 Mhz, it will be as follows.

      Signal Generator
      |
      |============== | ===========
      |-------------------> -------->
      |
      -----------------------------------
      27Mhz 27.0005__ 27.0010_____ 27.0020
      USB (Receiver)

      Then it changes to audio as below.

      Signal Generator
      |
      | ===============| ========
      |-------------------> -------->
      |
      -----------------------------------
      0__ 500Hz___ 1000Hz____ 2000Hz
      USB (Receiver)

      Then a 1000Hz sound is generated from the speaker. We look at it with the Spectrum app on cell phone.
      (LSB is the opposite. LSB will look at a frequency lower than the set frequency. So we call it the Lower Side Band)




      In this case, the Signal Generator generated a 27Mhz signal, but it is being received at 27.00326 at 1Khz.
      That means the Signal Generator will signal at 27.00426

      This means that the X-Tal connected to the Si5351 is 27Mhz, but actually it runs at 27.00426Mhz.


      If you send 27Mhz in AA and you hear 1Khz at 26998960 in USB mode on the receiver.

      It will be calculated as follows.
      26.998960 - 27.000000 + 1000 = -40Hz

      Because AA is relatively accurate, you only need to enter -40 in Calibration Value.

      Ian KD8CEC

      Delete
    2. Thank you very much for the comprehensive reaction on my question about the correction value for the analyser.
      Still I think it is the best way to draw a picture but I tried to mail you via amsat.org. That was not working. If you mail me via amsat.org I can send you a picture that will help us to make the question and my theory clear.
      Hope you can do that. If not ....no problem ...I am already pleased with your fast response to my question this way. All the best...'73 from Edwin, PA7EW

      Delete
    3. Edwin
      I do not have an account at amsat.org. I need to create an account. It was a place where there was a lot of interest.
      If possible, please send it to the following mail.
      kd8cec@gmail.com

      Ian KD8CEC

      Delete
  3. I join to the question of PA7EW.
    I tried to calibrate my FAA-450 on the your determening method for the correction value via the SSB receiver, but by rtl-sdr v.3 dongle and SDRSharp.

    1. I enabled Generator on 27 000 000Hz and connect FAA-450 directly to the out of rtl-sdr v.3

    2. By the audio and if spectrums of sdrsharp I found real frequency for 1kHz tone https://drive.google.com/open?id=1Y9ujNSXS5PXXVK3CQov2ipgZ7CDPEz-O
    and also rechecked it by spectorid app.

    3. Calculation:
    26998667 - 27000000 = -1333
    -1333+1000 = -333
    My calibration value is -333Hz

    4. I set SI5351_CORR to -333Hz on the FAA-450 and after restarting Generator got this:
    https://drive.google.com/file/d/1t8K7gmPLe4F44noLn8cPppfquh0nZZNM

    Is my calibration procedure and calculation correct?

    ReplyDelete
    Replies
    1. R1BET

      Perfect.
      It is normal that no sound is heard when AA transmits 27 Mhz and the receiver receives USB 27 MHz. We call it variously.

      If you set the receiver to 26.999000, you will hear an audio sound of 1Khz.

      For reference, there was a slight frequency error in my RTL-SDR.

      Ian KD8CEC

      Delete
    2. Thank you for answer and for your calibration method.
      Before starting of calibration procedure of FAA-450 I warmed up rtl-sdr v.3 under the heavy load during the couple of hours and then calibrate it frequency by the gsm method (kalibrate).

      Delete
  4. Hi,Ian!

    Everything works well for me (ver 0.35) and I have several suggestions:
    1. Set the band width to the middle of the screen (blue color) for each band,
    2. In the 60m and 4m band set the bandwidth,
    3. In the Panoramic scan mode screen and other screens, the call mark (EU1KY, CEC ... would be a more visibly, blue background and yellow text,
    4. On the main screen (bottom left) the version and date of the Firmware creation could be cyan colors.
    Hope I had to paint AA !?
    Thank you very much!
    73, 9A7JWX, Stjepan

    ReplyDelete
    Replies
    1. Stjepan
      Thank you for your good feedback.
      Everyone seems to be okay. I'll put your comments on the Todo List.

      Thanks agian

      Ian KD8CEC

      Delete

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