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Re: QCX-SSB: SSB with your QCX transceiver

Jerry Gaffke
 

Allison,

>>So phase must be accurate relative to what?<<
> The most obvious is RF phase ot amplitude phase

The envelope is changing at audio rates, looks like a flat line to our RF.
Not sure how to compare the timing of one particular edge of 14mhz RF with a flat line.
I think we are comparing the RF phase to what it was a millisecond or so in the past.

If speech is intelligible without any envelope modulation, that suggests this single square wave
that's always within 2 or 3 khz of our target frequency somehow contains information about
all the tones present, it must be in the phase of the square wave..
And if the information is at audio rates, then phase must be accurate across time periods
of a millisecond or more.  Hence this is hard.
 
I bet we'll have much less distortion due to phase errors on 160m than on 20m.
Perhaps synthesize the square wave at 200khz, up-convert to an HF square wave with a mixer?
That's what previous attempts at EER have been doing.

Using a buck mode switcher to modulate assumes there is always sufficient 
current draw to allow the output to quickly go lower when needed.
The QEX article mentions using a consumer type class D audio amp instead.

Take this all with a large grain of salt.
I don't yet have it figured out.

Jerry, KE7ER



On Sun, Feb 3, 2019 at 05:25 PM, ajparent1/KB1GMX wrote:
Jerry,

>>So phase must be accurate relative to what?<<

The most obvious is RF phase ot amplitude phase

More finely the extracted frequency from the modulation source
should exactly translate to the TX base frequency plus modulation
phase.  So if the input are stepped frequency tones from
200hz to say 2200hz the output frequency should also be base
frequency plus (minus for LSB) the base or carrier and increase
the same as the modulating tone.  It also must change at the same
rate.

For amplitude the average transmitter has about 50-60db of dynamic
range (can vary) from zero to full power and the granualatiry of processing
digitally may be less that fine causing waveform distortion.  For Guido's
code its 64 steps or barely 6 bits or rather coarse.  At extreme example
is CD audio at anywhere from 16 to 22bits.

So yes there are a lot of relative to self and also relative to processing speed
and sampling speeds all of which can if not carefully done create side bands.

Famous line is:  iF It wEre easy everyone would dOing it.  Ignore the
phase and amplitude errors in typing.

Allison


Re: QCX-SSB: SSB with your QCX transceiver

Steven Weber
 

11 us is 90.9 kHz. The other factor is how long does it take to do the required calculations? So long as you have an update rate faster then say 12 kHz, your doing good. The PWM rate I measured was 30.9 kHz, so it’s updating at a good clip. A lot of sound cards run at 44 kHz, right?

 

KD1JV

 

 

On Sun, Feb 3, 2019 at 02:26 PM, Jerry Gaffke wrote:
Si5351 frequency transitions when using the output multisynth dividers are instantaneous,

Yes and no.  Takes 11uS to transmit the change order.  At 7mhz 11US is 77 cycles.
at at 7.1mhz is 78.1..  frequency is time, phase is time.  Transmitting the data to
say do something takes time. 

Allison

 


Re: QCX-SSB: SSB with your QCX transceiver

Jerry Gaffke
 

> Takes 11uS to transmit the change order.

Ah, but i2c writes out to the si5351 are totally under our control. 
We can choose when the final register write gets kicked off.
As an extreme, could put down a $0.50 uC to keep time and bit bang the i2c bus,
perhaps with all interrupts turned off. s.


On Sun, Feb 3, 2019 at 05:29 PM, ajparent1/KB1GMX wrote:
Si5351 frequency transitions when using the output multisynth dividers are instantaneous,

Yes and no.  Takes 11uS to transmit the change order.  At 7mhz 11US is 77 cycles.
at at 7.1mhz is 78.1..  frequency is time, phase is time.  Transmitting the data to
say do something takes time. 

Allison


Re: Should we have a QCX QSO Party? #qcx

Rick
 

I’ll join in as well! If you need help organizing let me know. I’d be happy to help. 


Re: QCX-SSB: SSB with your QCX transceiver

ajparent1/KB1GMX
 

On Sun, Feb 3, 2019 at 02:26 PM, Jerry Gaffke wrote:
Si5351 frequency transitions when using the output multisynth dividers are instantaneous,

Yes and no.  Takes 11uS to transmit the change order.  At 7mhz 11US is 77 cycles.
at at 7.1mhz is 78.1..  frequency is time, phase is time.  Transmitting the data to
say do something takes time. 

Allison


Re: QCX-SSB: SSB with your QCX transceiver

ajparent1/KB1GMX
 

Jerry,

>>So phase must be accurate relative to what?<<

The most obvious is RF phase ot amplitude phase

More finely the extracted frequency from the modulation source
should exactly translate to the TX base frequency plus modulation
phase.  So if the input are stepped frequency tones from
200hz to say 2200hz the output frequency should also be base
frequency plus (minus for LSB) the base or carrier and increase
the same as the modulating tone.  It also must change at the same
rate.

For amplitude the average transmitter has about 50-60db of dynamic
range (can vary) from zero to full power and the granualatiry of processing
digitally may be less that fine causing waveform distortion.  For Guido's
code its 64 steps or barely 6 bits or rather coarse.  At extreme example
is CD audio at anywhere from 16 to 22bits.

So yes there are a lot of relative to self and also relative to processing speed
and sampling speeds all of which can if not carefully done create side bands.

Famous line is:  iF It wEre easy everyone would dOing it.  Ignore the
phase and amplitude errors in typing.

Allison


Re: Connectors for 10W PA

ajparent1/KB1GMX
 

Chopper yes you can.  If people look back it was explained by Hans.

I prefer to use coax to connector for testing.  Floppy wires at RF are unfrendly.

Allison


Re: 40 meter QCX #40m

Rob <palgrave@...>
 

Hi Ted,

Yes fault was in the same signal path as you say. I had tried carefully wriggling the L1 Toroid earlier but with no response either good or bad but on the last occasion I was a bit more persistent and yes there was a marked response that isolated the problem which was an easy fix. Hope such information is helpful to others.

Thanks again.

Cheers, Rob ZL1CV

On 4/02/2019 5:14 AM, qrp@... wrote:
Hi Rob

Interesting, it was essentially a fault at same place in the signal path as L1 connects directly the the antenna socket.
Might be a useful reference for future troubleshooters trawling the forum archive.

Very happy you managed to get your set functioning.


73s Ted
M7ECH


Re: ProgRock register report broken

KI7MWA
 

Some further investigation:  after setting all registers from 4 - 28 to 0, I began running successive register reports, adding a single digit to the value of register 4 prior to each report, i.e. 1, then 11, then 111, et cetera.  With the exception of the first report, with register 4 containing "1", the breakdown in the register report moved "up" with each successive report - that is, the breakdown appears to be dependent on the number of characters sent, the more characters sent in the early part of the report, the fewer characters are correctly transmitted toward the end.

Like this:
(registers 0-3 as normal)
4:1
5:0
6:0
...
11:0
12:0
13.0
garbage

then
(registers 0-3 as normal)
4:11
5:0
6:0
...
11:0
12:0
garbage


Re: ProgRock register report broken

geoff M0ORE
 

I am using the sketch as described in the manual, page 7, to set the Arduino Nano ( which I already have) and the TeraTerm and Hypertrm to communicate  with the progRock and mostly works OK except for the single registry query. i.e. 4? , when I get no response. A general query of "?" gives the expected result for all registries. I have never got a report like the one in your attached file.

When I get the new processor chip, I will be able to play with mine again. Stuck in customs shed at Heathrow I expect.

Geoff

On 2/3/2019 10:01 PM, entilleser via Groups.Io wrote:
Everything was working fine, things looked like the operations manual said it should.  Then I tinkered with some of the circuitry, working toward connecting to the Receiver Module.

Now, things are mostly okay, with the exception of the "?" command, which now produces a semi-broken report (see attached file).  I can still set and query individual registers.  I thought it might be the result of some timing misalignment, so I put a delay in the loop reading from the ProgRock, which resulted in an earlier deterioration of the register listing.

I'm using an Arduino Uno to communicate with the serial output of the ProgRock, showing the output in the Arduino IDE serial monitor as well as a 4x40 LCD, at 9600 baud, with CR only for end-of-line, my sketch is using the SoftwareSerial library for communication with the LCD.

Have I tweaked the microcontroller on my ProgRock or does this sound like a communication problem?  


Re: Connectors for 10W PA

Jerry Gaffke
 

From the photos, not clear how the PA connects to the rest of the radio.
Could be wires.  Could be header pins.
I'd just solder wires to the pads for testing, perhaps stuff a toothpick into the holes first
so they remain clear of solder.

Jerry


On Sun, Feb 3, 2019 at 01:03 PM, Chopper wrote:
Sorry maybe I was not clear on my question.  I realize the final wire lengths will be short.  I was hoping to use slightly longer lengths to connect to an RF connector and power source wiring and once tested, cut them to the final assembled radio length ( once exact length is specified),  Was not sure if coax will be required from final board to amp input.


Re: QCX-SSB: SSB with your QCX transceiver

Jerry Gaffke
 

So phase must be accurate relative to what?
I'm now thinking that the phase of our square wave from the si5351/si5340 must be
accurate with respect to that same square wave over a time interval on the order of
the period of the lowest frequency in the audio that we are modulating with.
Correct within a small fraction (perhaps 5%?) of one RF cycle.
A very tall order indeed, if that''s right then I agree that the VCXO scheme would not work.

Si5351 frequency transitions when using the output multisynth dividers are instantaneous,
take effect immediately when the final multisynth register is written to.
That might be best the implementation to maintain phase accuracy.

In the case of using PLL multisynth dividers, there will be an unknown amount of time
for the VCO to slew to the new target frequency, a function of the loop filter
that SiLabs has in their PLL.

Locking the processor to the si5351 should be quite easy, just drive the processor clock
from one of the other si5351 outputs.  Or perhaps from the 25/27mhz reference oscillator.

Jerry, KE7ER


On Sun, Feb 3, 2019 at 09:53 AM, Joshua Blanton wrote:
In order to correctly do so, you must integrate the frequency change over time to arrive at the proper phase - and the only way you have a chance of accuracy is if your frequency steps are known, and finite enough to provide a slow phase/time shift.  It also seems to me (intuitively - I haven't done the math to prove it!) that the clock accuracy of the processor matters quite a bit


Re: Projected release date on QSX?

Kwacka
 

Glad to read you and your faimly's health are improving, also glad you;got your priorities right (even though I'm like a kid waiting for Xmas).

I recovering from dose of the 'flu and passed it onto 'The Boss'  - she's home after a few days in the local hospital - so know how disabling it can be, and have some idea about how worried you must have been when your family became ill.

Many thanks for everything you've done for our hobby.

Paul, 5B8BA


ProgRock register report broken

KI7MWA
 

Everything was working fine, things looked like the operations manual said it should.  Then I tinkered with some of the circuitry, working toward connecting to the Receiver Module.

Now, things are mostly okay, with the exception of the "?" command, which now produces a semi-broken report (see attached file).  I can still set and query individual registers.  I thought it might be the result of some timing misalignment, so I put a delay in the loop reading from the ProgRock, which resulted in an earlier deterioration of the register listing.

I'm using an Arduino Uno to communicate with the serial output of the ProgRock, showing the output in the Arduino IDE serial monitor as well as a 4x40 LCD, at 9600 baud, with CR only for end-of-line, my sketch is using the SoftwareSerial library for communication with the LCD.

Have I tweaked the microcontroller on my ProgRock or does this sound like a communication problem?  


Re: Connectors for 10W PA

N3MNT
 

Sorry maybe I was not clear on my question.  I realize the final wire lengths will be short.  I was hoping to use slightly longer lengths to connect to an RF connector and power source wiring and once tested, cut them to the final assembled radio length ( once exact length is specified),  Was not sure if coax will be required from final board to amp input.


Re: 40M BPF alignment T1 and C1 #qcx #alignment #bpf

James Daldry W4JED
 

Hi, Bill

Sorry to rain on your parade, but if peak comes at full mesh of C1, that means you are using the capacitor to compensate for insufficient inductance. You need to either (a) add turns (which either means make it ugly or rewind the big winding) or (b) add a capacitor across C1. The added cap should be either NPO or silver mica.

Jim W4JED

On 2/3/19 10:21 AM, Bill Wrbican wrote:
I've completed a 40M QCX (built the 20M last year). Doing the BPF alignment, I could only get max signal with C1 nearly fully meshed (at a power of 10), so I removed 5 turns from T1 (which was easier than I thought). However I still get the same issue. A power of 10 seems way higher than others I've seen, and I wonder if I should stop messing with it and just continue, or if there is something with C1? Through one complete turn of C1, the scale moves several bars, but never leaves the 10 scale (it was this way prior to removing the turns as well).

Bill
KA3BMU


Re: 40M BPF alignment T1 and C1 #qcx #alignment #bpf

Bill Wrbican
 

on another reading of the manual, I seem to have misread it. Rats. OK, I'll have to add some wire to the winding, in addition to what I removed. 

I'll check C5 while I'm at it.

Thanks!


Re: U3S Menu Configuration Settings

Bob ZL1RS
 

OK Ken.  I used the U3S Park mode LO here on my QRP Labs RX for WSPR RX (single band) before RX mode was introduced more recently, and the sensitivity was fine (very little difference between simultaneous WSPR spots from the QRP Labs RX kit and my IC-7600 when Tee'd off the same RX antenna).  But I see the need for U3S RX mode in multi-band RX use.

73, Bob  ZL1RS



Re: Connectors for 10W PA

ajparent1/KB1GMX
 

Likely around an inch, not enough to facilitate testing.
For testing you want RF connectors to hook up loads and such.

Allison


Re: QCX-SSB: SSB with your QCX transceiver

ajparent1/KB1GMX
 

Josh,

You have pointed out of of my tech references (including Khan's paper in '52) and others.
Whats useful about the Polar explorer is where you end up when you build hardware to
get a still less than stellar signal.  His output spectrum show the problems for a fairly
high resolution system using a much fast 32bit cpu.   Imagine how that decays for
a slightly slower 8bitter.

Again with emphasis there are two areas for distortion and spurious signals in the system.
One is the phase modulated RF source, the other is the hardware to amplitude modulate it.

Once you have a fairly fast 32bitter and 14bit or more ADC and DACs then other
SDR techniques offer better chances for improved quality of signals and no greater
amount of hardware.

My level of curiosity is the proposed QCX based framework is how bad and can it get
to semi decent.

Allison