Topics

Band Scan and S-Meter


Dennis A
 

I have successfully installed the standalone signal analyzer and Nextion screen on a uBITX v.6. This is an amazing extension to the uBITX radio.  I do, however, have two basic questions.

How can I change the upper limits of the bands scanned in the Band Scan function? It currently does not scan the top of the US bands. By the way, where in the source is this function implemented?

HRD suddenly stopped showing the s-meter. It's fine on the screen, is there an HRD setting or a CEC setting I need to change? 

Thanks.


Jack, W8TEE
 

Dennis:

When you post something like this, you should state which AA you are using as there are at least a dozen flavors out there and without knowing which one you're talking about, it's hard to offer help.

Jack, W8TEE

On Sunday, February 7, 2021, 3:47:53 PM EST, Dennis A <ac9kq@...> wrote:


I have successfully installed the standalone signal analyzer and Nextion screen on a uBITX v.6. This is an amazing extension to the uBITX radio.  I do, however, have two basic questions.

How can I change the upper limits of the bands scanned in the Band Scan function? It currently does not scan the top of the US bands. By the way, where in the source is this function implemented?

HRD suddenly stopped showing the s-meter. It's fine on the screen, is there an HRD setting or a CEC setting I need to change? 

Thanks.

--
Jack, W8TEE


Dennis A
 

Hi Jack,

Unfortunately I don't know what you mean by AA. Which, of course, only illustrates my newbie ignorance. If you  could let me know what the acronym means, I'll try to provide more information. 

Thanks for your willingness to help. Sorry I didn't provide enough information.

Dennis, AC9KQ


Evan Hand
 

Dennis,

Congratulations on the KD8CEC with Nextion and standalone analyzer implementation.

I believe that the band settings can be changed with the KD8CEC Memory Manager program that is available here:
https://github.com/phdlee/ubitx/releases/tag/v1.11

I do not have the standalone version on any of my uBITX, so beyond the above, I can not be of more help, if the above even does point to the solution.

Good Luck!
73
Evan
AC9TU.


Jack, W8TEE
 

Sorry, it means Antenna Analyzer.

Jack, W8TEE

On Sunday, February 7, 2021, 6:04:00 PM EST, Dennis A <ac9kq@...> wrote:


Hi Jack,

Unfortunately I don't know what you mean by AA. Which, of course, only illustrates my newbie ignorance. If you  could let me know what the acronym means, I'll try to provide more information. 

Thanks for your willingness to help. Sorry I didn't provide enough information.

Dennis, AC9KQ

--
Jack, W8TEE


Dennis A
 

Jack,

Sorry I wasn't clear. By band scans on the "standalone signal analyzer" I was referring to KD8CEC's IC2 type signal meter based on a second Arduino (http://www.hamskey.com/2018/07/standalone-signal-analyzer-i2c-type_29.html), not an antenna analyzer.

I understand your question now.

Evan,

I found the bands setting in the Memory Manager and successfully updated them, but the band scan function still uses the more restricted band limits.  I was hoping to find the band scan in the code and figure out what's going on.

Thanks to both of for your responses.

de Dennis (AC9KQ)


Evan Hand
 

On Sun, Feb 7, 2021 at 09:37 PM, Dennis A wrote:
I found the bands setting in the Memory Manager and successfully updated them, but the band scan function still uses the more restricted band limits.  I was hoping to find the band scan in the code and figure out what's going on.
Dennis,
I looked in the code, and believe that the bands are being read from the main EEPROM.  With that assumption, I am not sure why it was not updated correctly.  Did you use the region 2 automatic input and then write to the uBITX?


Also, there are two versions of the code.  Can you verify which version you are using?

Just some possible ideas.
73
Evan
AC9TU


Evan Hand
 

Dennis,
One other possibility is to look into the Nextion HMI code.  It may be that the values are stored there.  Can you send a link to the screen hmi file that you used?  the tft file will not give the details.

73
Evan
AC9TU


Dennis A
 

Evan,
You are right! 

The band scan is controlled by the Nextion HMI code. On the pbandscan page in Dr. Lee's ubitx_28.HMI the initial frequencies for each of the three bands scanned is determined by the touch event associated with each of the four band selections at the bottom of the screen. These values are hard coded. For example the leftmost button sets the beginning frequencies for 80, 40, and 20 meters as follows:

nBand1.val=3500000
nBand2.val=7000000
nBand3.val=14000000

The tm0 timer event, which drives the actual scan, sets 2k frequency steps and scans through 120 steps, giving a 240k range on each band scan. And there it is! This gives a top frequency, for example, in the 80/75 meter band of 3.740.000, well below the top of the region 2 phone allotment. 

Since I am more interested in the phone segments of the bands right now, I'll probably modify the HMI file with higher initial band frequencies. Or perhaps change the selections to upper and lower band ranges where appropriate. Just have to dig the Nextion out of the case to insert the microSD card.

I did not realize how much processing the Nextion actually does. No wonder I couldn't find any of this function in the code for either Arduino. 

Thanks for your help.

73
Dennis
AC9KQ


Evan Hand
 

Dennis,
What would happen if you change the number of points scanned?  That might require a code change in the Nano to allow for a larger buffer size, I have not really dug deep enough in the code to verify that  If the response is not too slow, might try doubling the number of steps.

Worth a try in my opinion.
73
Evan
AC9TU


Dennis A
 

Hi Evan,

I think the number of steps relates to the number of vertical bars the Nextion can display with reasonable clarity on a 2.8" screen.

Alternatively, I could change the step size to cover more range. 2500 x 120 would give 300k bandwidth. I'll play with it and let you know what I come up with.

Really appreciate your help.

73
Dennis
AC9KQ


Evan Hand
 

Dennis,
The resolution of the Nexion is 320x240,  I do not know the screen layout, but with adjustments you could go with more steps.  I do believe that there are two possibilities that could be limiting:
1 - The FFT function in the Nano
2 - The SSB filter width.

Going to 2.5kHz may not give much boundary data to do the FFT.  I suspect it is the array sizes needed to do the processing, point 1 above.

Another option I just thought of would be to read the current frequency and adjust for +/- 60 data points on either side.  The buttons could be changed from Band to left, center, and right of the frequency on the display at the time of press.

The issue with any of the above is the limited resources in both the Nextion and the Nano.  The Nextion already complains about being out of memory on any additions.

Will be curious to see your results.
73
Evan
AC9TU


Dennis C (WC8C)
 

I think this function does not use the Nano FFT (I have been in the code a lot for the Nano FFT, and it only kicks in for CW decode to the ~ 3KHz spectrum display).  For the band scan, I think what it happens is the Nextion changes the VFO, then checks the SMeter value coming in.  The SMeter comes in from the Nano, but it doesn't do FFT to get it.  It takes some samples then uses the highest/lowest sampled to calculate the SMeter value.

Note: I am a different Dennis that the OP
--
Dennis WC8C


Evan Hand
 

Dennis WC8C,

I am sure you are correct.  I have not dug that deep into the Nextion code to see where it is getting the data.  That could also be where the limits come in.

I will look at the Nextion HMI file when I get a chance.

Again Thank you for the information.  I am always looking to learn more.
73
Evan
AC9TU


Dennis A
 

Hello Dennis C WC8C,

My observation of band scan and the spectrum scan screen operations and the Nextion code are consistent with your ideas. It seems to calculate and plot an S-meter value at each 2k increment. I find both of these screens useful for finding active frequencies. It's not the band screen from my 7300, but it's pretty cool for a project radio.

Since you've dug around in the FFT code, perhaps you might have an idea about a problem in my 3k spectrum display on the SDR.1 menu and the home screen.  It almost always presents a something that looks like a rough graph of 1/x. 99% of the time the number in the display is "30."  It looks the same for an USB or SSB voice signal, CCW, FT8, etc.  All signals seem to be received just fine, but the spectrum graph doesn't show the shape of the signals across the 3k band. Consequently I can't use the slider to position the CW decoder on a signal to be decoded.  Any suggestions?

I'm running a uBITX v6, with a kit-projects.com AGC mod installed and, of course, the CEC firmware. I'm taking the S-meter tap from the AGC board to the A7 pin of the second Arduino.

Thanks for any suggestions.

Other Dennis
AC9KQ


Dennis C (WC8C)
 

I actually totally re-did the FFT part of the code and made a number of other improvements.  The original FFT code had an odd bin size, so there was a progressive frequency offset from the FFT display to reality.

If you are comfortable dealing with Arduino stuff, my project is at https://github.com/soligen2010/dspmeterv1

That being said, there are limits to what the Nano ADC can do.  I think it is useful to find CW signals, but getting an accurate shape of a 3KHz signal, I am no so sure.
--
Dennis WC8C


Dennis A
 

Dennis C -

Thanks. I'm comfortable with the Arduino programming environment. Your extension look very interesting.  I'll give it a try and let you know what I think.

Dennis A
AC9KQ


saquib.ahm88@...
 

Thanks! It a great help! SWL from India Awaiting for my license


Dennis C (WC8C)
 

Turns out that the Band-Scan works differently that what I posted earlier.  Here is what is does - for both the Band-Scan and Spectrum screens

Nextion sends the scan request to the CEC Raduino asking for a scan with 2kHz increments,
The Raduino loops through the frequencies and does one of 2 things:
  • Reads the SMeter ADC pin on the Raduino (for conventional SMeter)
  • Or, Asks for the SMeter value from via I2C from the dspmeter (second Arduino Nano)
The I2C SMeter should scan slower than the conventional SMeter because there is more work and communication to do there, but I have never used the conventional SMeter, so I don't know how noticeable a different it is.

I looked into this because Dennis A let me know my "Improved" I2C dpsmeter code broke the Band-Scan function, but I am on the path to a fix.

--
Dennis WC8C