On Fri, Sep 1, 2023 at 10:08 PM, Colin Kaminski wrote:

I may have a simplistic view, and I hope to be corrected, but it seems to me that an EER method can only reproduce a single tone at a time. The code tracks the loudest frequency and duplicates. The wave shaping circuit changes the volume. ?This can not generate a true two tone signal.?

If you look in the audio domain, you have a two (or multi) tone signal. ?However in the RF domain, you see close to an almost pure single frequency RF waveform with nearly invisible frequency changes (on the 20M band, SSB modulation only changes the RF frequency by 2.5kHz/14MHz or a max of 0.02% change). ?Those changes are very slow (audio rate) compared to the RF frequency, but can include an array of many microscopic sidebands, a lot more than just two. ?So you can change a narrow-band close--to-pure RF waveform in amplitude and phase by tiny amounts at a relatively slow rate, and end up with tons of audio frequencies when those tiny-at-RF sidebands are modulated back down to baseband, where they now become large differences relative to each other in terms of rich audio.
--
73, Ron, n6ywu

On Sat, Sep 2, 2023 at 02:17 PM, Stephan Ahonen KE0WVA wrote:

The real trick to understanding this will be to develop an understanding of the IQ representation of RF signals. Seeing what an FM signal looks like on an IQ diagram, and seeing what an AM signal looks like, and understanding why those signals look the way they do, is really the key to understanding the fact that every arbitrary signal can be broken down into FM and AM components.

Conversely, given sufficient bandwidth and precision of the IQ data stream it is possible to generate any arbitrary signal, or combination of signals, of any modulation types.??
73, Don N2VGU

On Sat, Sep 2, 2023 at 10:24 AM, Da Amazin' man G0FTD wrote:

Surely this just amounts to creating? at any given point in time only one sampled frequency
and then switching to another fast enough in order to give the effect of two or more
simultaneous tones ?

In an analogue system? then ALL the tones of speech are present simultaneously.

--
- 73 de Andy -

In the simple case of two simultaneous tones, you are not modulating frequency at all. You can produce two tones solely through amplitude modulation.

Think about the spectrum of an AM signal - an AM signal produces two full sidebands without changing the frequency of the oscillator at all, simply by modulating amplitude.

To produce an SSB signal, you add some frequency modulation to the above procedure. Not by tuning the oscillator to every frequency in the entire signal, but rather by tuning the oscillator to the "instantaneous frequency" of the signal at any particular moment, the same way you produce a full spectrum of sound by making a DAC produce the instantaneous voltage of the signal from moment to moment.

The real trick to understanding this will be to develop an understanding of the IQ representation of RF signals. Seeing what an FM signal looks like on an IQ diagram, and seeing what an AM signal looks like, and understanding why those signals look the way they do, is really the key to understanding the fact that every arbitrary signal can be broken down into FM and AM components.

Hello Chuck,
I just noticed your message. I am trying to get my QDX-M to work with andFLmsg on an android phone, so a different application from you. I might however be able to solve the first part of your problem of getting the phone to recognize your QMX.
I obtained a terminal app from the Play Store, I used "Serial USB Terminal". Once the app was installed and I had connected by OTG cable to the QDX, I opened the app menu, selected USB devices and found there the QDX device. Selecting it caused the app and QDX to connect. I then selected the radio app I wanted to use (in my case andFLmsg) and I was able to communicate and send text to the QDX for transmission using Olivia (in VOX mode). I am still having problems receiving audio back from the QDX to the phone, but I figure I am more than half-way there!
Let me know if this works to establish communication between your phone and QMX.

Also if one of the secondary windings is reversed it may cause the problem.

You've probably already done it but I would check continuity from IC 402 pin 7 to IOC 403 pins 7 and 9. And to ground ~5k ohm

After looking again, it looks like the pin on the far left may not be hitting the pad at all --?
Bruce

Check that there is no short in this circled location.? Also, this IC is a little skewed to the right, make sure all of its pins are nicely connected to the pads.
This is the most likely area of concern giving your symptoms. Good luck!
73
Bruce
KG8IW

Hello all,
I have a 40m qcx+ and a qlg1, both working great together on wspr for several years now. Well, that until I went ahead and put my qlg1 in a new enclosure, on top of that I removed the 3mm LEDs (attached to the board) and replaced them with 5mm LEDs attached to longer wires so they would attach to the enclosure. On first test the qcx+ and qlg1 talk to each other fine, the qlg1 locked on satellites and all, but I noticed that the qcx was not outputting any power. The qcx+ transmits perfectly fine without the qlg1 attached. I obviously broke something, however I am not sure if I broke the qlg1 or the qcx, do you guys have any clues? Thanks

?Don

If you would like to try signal tracing
Here is a? very nice PC soundcard oscilloscope for win XP and above
As you know surface mount components are packed tight
Be careful probing
I use a hat pin, small sharp point so not to skip off component es short to another,? plastic knob so personal contact does not introduce noise or 60 Hz junk

https://www.zeitnitz.eu/scope_en

It is also dual channel with a spectrum analyzer and sweep generator? And Free

72 73
John
N3AAZ

开云体育

Yes, but in the RF domain you need frequency and amplitude.?

73, Willie N1JBJ

Voltage on C406 is 2.42V so I guess its correct. Just in case I will rewind T401 trifilar transformer in case there is a shortage inside winding.
---------------------------------
73 de Marek SP9TKW

Hi John,

From research undertaken seems that WSPR on upper VHF bands for DX propagation is not very effective. Have found more than one study / paper that arrives at the same conclusion.

73

Nigel ZS6RN

On Sat, Sep 2, 2023 at 04:24 PM, Da Amazin' man G0FTD wrote:

In an analogue system? then ALL the tones of speech are present simultaneously.

Excepting xtal filter group delay params.

That's why SSB always has that SSB sound, unless you're using a DC RX ;-)

--
- 73 de Andy -

Surely this just amounts to creating? at any given point in time only one sampled frequency
and then switching to another fast enough in order to give the effect of two or more
simultaneous tones ?

In an analogue system? then ALL the tones of speech are present simultaneously.

--
- 73 de Andy -

Well I have tried all the suggestions, quadruple checked the solder joints. There is NO sound other then the initial click at power up. It will work fine on Ft8. With FLdigi I can decode CW. The Device successfully Will transmit CW and decode CW both with the Key and on the air. Just nothing out of the head phone jack. I purchased another kit and am going to build it and then compare and contrast the two. If anyone has any other suggestions I'd love to try them.?

? Don..?

On Sat, Sep 2, 2023 at 02:18 AM, Stephan Ahonen KE0WVA wrote:

What does the waveform of a two tone signal actually look like? The actual waveform, if you squint at it really hard, just looks like a single tone that's being amplitude modulated at the beat frequency between the two tones, and inverts polarity whenever the amplitude modulation has a zero crossing.

When I was writing my Teensy version of the uSDX I thought one day I would inject a perfect two tones programmatically and learn some things about the Si5351 frequency generation algorithms but much to my surprise the result was exactly as Stephan says but without any squinting.? Two tone testing the uSDX method of SSB is only a test of the AM modulator.

I found that the SSB method is/was limited by the I2C bus speed and a more powerful processor does not gain you anywhere near as much improvement as one might expect.? It will be interesting to see what Hans can do as he seems like a very smart fellow.

Ron? KE1MU