pixie net on last wednesday of every month

#4816

last wednesday of every month at 01:00 utc or 9 pm est. we use
(in order to text/chat) we are here to help to assure you that your pixie works, etc.

there are 20m and 40m pixies so come and join us March 27. and to exercise your qrp cw

any questions ka1uln@...

ADX-S 4 bander, update your firmware to get 2 more free bands

#4815

Guys,

If you upgrade your firmware to V1.3, you can support up to 7 band, but normally you will need to make 7 band filter modules. However, for 4 bander users, you can consider reuse your 10m module for 12m, and 15m module for 17m. You will be surprised about the results.

Can we also reuse 20m module for 30m band? No. The spur will be quite bad.

How can we upgrade the firmware? Read the Assembly Manual and download the necessary files in this folder:

/g/crkits/files/ADX-S

If you know how to modify the code, it is recommended that you modify this line to enable ATT by default, that is, change from int attnow = 0 to 1. It is important if you have a fair or better antenna.

int attnow = 0; //0 = no ATT, 1 = ATT

Thanks,

Adam

Re: ADX-S mod for use with trusdx-audio

#4814

In uSDX's SSB mode, the audio signal is first digitally processed into two audio signals that are 90 degrees out of phase (I/Q signal).
The phase component (frequency change rate) and amplitude component of the SSB are then calculated; the oscillation frequency of the Si5351 is determined from the phase component and varies at approximately 5 kHz (almost the maximum frequency change rate of the Si5351a).
The amplitude component is controlled by an 8-bit PWM from the ATmega328.
I am not sure about the digital mode of the (tr)uSDX, but I believe it basically uses this SSB mode.

?

In this case, it is basically the same as ADX, where the oscillation frequency of the Si5351 is varied by measuring the period of the audio signal and calculating the audio frequency.
Therefore, the amplitude component is completely ignored. ?
Recent systems such as WSJT-X slowly increase the amplitude at the start of transmission to reduce spurious signals, which is not supported by this method.?

The analog comparator of the ATmega328P is fast enough to obtain a relatively accurate value simply, and the ADX finds the period and calculates the frequency in this way.
On the other hand, with digital audio signals, it is necessary to find the period more accurately than the sampling interval (in this case, 1/11520 second).
For this reason, the time at the zero cross point is calculated by proportional distribution from the values before and after passing through the zero point.?
The period can be determined from the times of the zero cross points.
In this case, the negative to positive and positive to negative points are used to calculate the period, respectively.
If all the audio data can be received correctly, the frequency can be measured with an accuracy of less than 1Hz in a 10ms measurement.?

Thanks,
Hitoshi, JE1RAV

Re: ADX-S mod for use with trusdx-audio

#4813

I have to admit that I don't fully understand the transmit section of the (tr)uSDX audio modification.? RX, yeah sample, scale and send.? But the other direction is more complex.?

I understand that the conversion from input audio samples to pwm in that streaming audio output project is a key to this, but instead of converting the pwm generated to an output, I am guessing that the frequency is calculated somehow and that offset is added to the si5351 as opposed to the timer count with the zero crossing comparitor generating the frequency offset.? But looking at the code I don't quite get it.?

An interesting experiment could be to use the original code to generate the tones as a pwm audio output and see how well it follows the transmit tones.? If you are having issues on TX Adam, then it's going to be in that code that converts the input samples into the pwm values.? I wonder again if a zero crossing (crossing 128 in an 8 bit sample) couldn't be used instead except there isn't going to be a interrupt available to fire off the counter isr.?

Interesting implementation.? I need to think about it.? I will try to figure it out in the next couple of evenings.?

I still am finding this quite fascinating but again I wonder how the amplitude of the transmit samples affect that library.? Maybe mathematically limiting the audio first would help.?

I guess I have some experiments to run once I figure out what the outgoing TX does.?

Fred W0FMS?

Re: ADX-S mod for use with trusdx-audio

#4812

I will but it might be a few weeks before I am done with the modification, I am crazy busy so I can only work on it maybe an hour a day.?

It does work okay on my (t)rusdx, though.? I can confirm that.? The only issues I have had with that is if the audio level is too high ft8cn audio driver will crash on receive.? The pc side doesn't have this issue.? On the trusdx you can set the audio level coming back on the serial interface by simply adjusting the volume setting on the rig.? I find it's okay if it's set a little lower than I would typically use.?

Since the tone on the ADX-S is coming through the serial port on transmit, and then counted instead of the AD input maybe something is overflowing on that end.? I need to study the code.? IIRC, the serial interface is only sending 8 bits both ways so instead of 10 bits from the ADC.? Some math might need to be done on RX for software AGC and maybe scaling the data up by a factor of 4? on TX might make it work better.

I hope I remembered correctly about that interface.? I think it's 8 bits but I should verify it.?

I got my replacement Amazon LM386M boards, and I modified one to a non inverting version of that circuit.? Ground off the output cap portion on the board and it fits pretty well on it.? Picture attached to see where I am at with that.?

IMG_20240318_184545889.jpg

Re: ADX-S mod for use with trusdx-audio

#4811

开云体育

Fred,

Before hardware modification, you can test the firmware and PC software for TX. In my case, it can TX but the tone is not stable sometimes, so it is difficult to decode. Perhaps you can test and share the results. I am using Win 7 on a very old ThinkPad.

Thanks,

Adam

Show quoted text

在 2024年3月18日，12:10，Fred Spinner <fred.spinner@...> 写道：

?Thanks.? I was sent a literal bag of garbage (someone's fraudulent return) instead of the boards I ordered from Amazon so I have not started the conversion of the board and addition to the rig.? Thanks for letting me know about the gain difference.? I might experiment with leaving the potentiometer on the input of the board so I can tweak it.? I will report back when I try it.? I want to take this out in the field and I don't do Manhattan or deadbug style well enough to not mount a daughterboard.? If the one I ordered is suitable I will let the group know.? This is such a fun project.?

Fred W0FMS?

Re: ADX-S mod for use with trusdx-audio

#4810

Thanks.? I was sent a literal bag of garbage (someone's fraudulent return) instead of the boards I ordered from Amazon so I have not started the conversion of the board and addition to the rig.? Thanks for letting me know about the gain difference.? I might experiment with leaving the potentiometer on the input of the board so I can tweak it.? I will report back when I try it.? I want to take this out in the field and I don't do Manhattan or deadbug style well enough to not mount a daughterboard.? If the one I ordered is suitable I will let the group know.? This is such a fun project.?

Fred W0FMS?

Re: Now you can pre-order TCXOM on CRKITS.COM

#4809

Already shipped, one week ahead. Now ready to take more orders.

Thanks,
Adam

Show quoted text

在 2024年3月12日，23:40，Adam Rong via groups.io <rongxh@...> 写道：

?Guys,

I have made available the green TCXOM instead of the entire module, as I have little time to do the rework myself. You can place order now, 1 or 5 pcs a time, and I will ship no later than March 25.

Thanks,

Adam

Re: ADX-S mod for use with trusdx-audio

#4808

Dear Fred,

The receiving antenna (magnetic loop antenna) used for reception testing was out of tune when tested.

After tuning and testing today, it appears that the gain of the LM386 (x 200) was too high.

Therefore, the LM386 should be used with a gain of 20.

Sorry, please remove the C2 (10uF) capacitor in the circuit.

Thanks,
Hitoshi, JE1RAV

Re: ADX-S mod for use with trusdx-audio

#4807

By the way, using the LM386 as the amplifier for the AVR ADC input was extremely clever.? Thr LM386 inputs are ground referenced but the output internally is vcc divided by two which on 5V will properly bias the ADC inputs at 0 to 5V.? I think I might modify my ADX-S with this modification by modifying a commercial SMT device "microphone" amplifier module by removing the input DC bias resistor for the mic and the output components to drive a speaker on that board. Maybe grind down the physical size of the board on the output side.? ?The only difference then on that board would be an additional bypass cap on vcc and it being configured as a non inverting amplifier instead of inverting which I imagine would still work. (and if not would be easy to further modify.)?

What a great little modification to an already fun little rig.?

Fred W0FMS/7

Re: ADX-S mod for use with trusdx-audio

#4806

Dear Adam,

I have uploaded a new firmware.

The CAT controller part has been slightly changed.

Could you please test it?

I hope it will work.

Thanks,
Hitoshi, JE1RAV

Re: ADX-S mod for use with trusdx-audio

#4805

Hi Adam,

I found a mistake.
Please wait the test after fixing it.

Hitoshi, JE1RAV

Re: ADX-S mod for use with trusdx-audio

#4804

Dear Adam,

I still haven't figured out why the "TX" command is not being received in your case, could you test the new firmware uploaded on github?

Thanks,
Hitoshi, JE1RAV

Re: ADX-S mod for use with trusdx-audio

#4803

The firmware of ADX by WB2CBA is not fully supported for CAT PTT ("RX" and "TX"commands).
Only the BS170 rf-switch is treated by the commands and the output of Si5351 is not treated.
This is the reason why CAT PTT method is not working properly in the firmware.

Those parts have been treated in my firmware, so it work if the command "TX" or "RX" is received properly.
The problem seems to be the receiving of "TX" command, since the audio data are also send and received by serial communication.

Thanks,

Hitoshi, JE1RAV

Re: ADX-S mod for use with trusdx-audio

#4802

开云体育

Hitoshi-san,

It is an existing issue. When I was porting the CAT code for ADX-S, I found the CAT PTT method is not working, so I relied on VOX still. It seems the audio via serial port does not trigger VOX.

I am curious why you are okay. Any difference?

Thanks,

Adam

On 2024/3/16 10:23, Hitoshi, JE1RAV wrote:

Show quoted text

Thanks Adam

I understand the situation.
RX S meter on WSJT is jumping into zero when the transmission starts on WSJT-X but ADX-S does not go into transmission.
I must consider the reason why "TX" command is not received properly in ADX-S.

Thanks,
Hitoshi, JE1RAV

Re: ADX-S mod for use with trusdx-audio

#4801

Thanks Adam

I understand the situation.
RX S meter on WSJT is jumping into zero when the transmission starts on WSJT-X but ADX-S does not go into transmission.
I must consider the reason why "TX" command is not received properly in ADX-S.

Thanks,
Hitoshi, JE1RAV

Re: ADX-S mod for use with trusdx-audio

#4800

开云体育

A2 was used for another purpose and it is at a stable DC voltage.

On 2024/3/16 9:41, Hitoshi, JE1RAV wrote:

Show quoted text

Thanks Adam,

"TX" command seems to be not received properly.
Can I ask for a retest after A2 pin treatment?
The simple one is connect to ground.

Hitoshi, JE1RAV

Re: ADX-S mod for use with trusdx-audio

#4799

Thanks Adam,

"TX" command seems to be not received properly.
Can I ask for a retest after A2 pin treatment?
The simple one is connect to ground.

Hitoshi, JE1RAV

Re: ADX-S mod for use with trusdx-audio

#4798

开云体育

Hitoshi-san,

Thanks! I suppose the RX level bar jumping is normal, as I haven't modified the hardware, so the A2 pin is floating. After modification, it should be at 1/2 VCC or around so the level bar should be stable.

The only problem is the TX. CAT is working, but the PTT control does not work, even I tried CAT or VOX method.

Thanks,

Adam

On 2024/3/16 9:22, Hitoshi, JE1RAV wrote:

Show quoted text

Could you describe a little more about that behavior?

Hitoshi, JE1RAV

Re: ADX-S mod for use with trusdx-audio

#4797

Could you describe a little more about that behavior?

Hitoshi, JE1RAV