Topics

#uBITX Firmware KD8CEC - IF-Shift etc. #ubitx

Rod Davis
 

Jerry,

 Huh? The formula correction at the bottom seems to be
no-change.  Is that what you meant?

Rod KM6SN


On 03/11/2018 07:43 AM, Jerry Gaffke via Groups.Io wrote:
It was getting late when I pressed send, a couple minor errors crept in:

>  The 12mhz filter is passing audio between roughly 500 and 2500 hz in its upper sideband,
>  so the 12mhz filter is probably centered around 11996500 + (500+2500)/2 = 1199800 hz.
>
>  With a clk1 for USB of 56995000 hz, the center of that upper sideband in the 45mhz filter
>  would be 56995000-11998000 = 44997000 hz
>  With clk1 for LSB of 32995000 hz, the center of that lower sideband in the 45mhz filter
>  would be 32995000+11998000 = 44993000 hz.

When I say "upper sideband in the 45mhz filter", I'm talking about the upper sideband
of the original signal.   Should rewrite those last few lines with a few more words:

  With a clk1 for USB of 56995000 hz, the center of that sideband within the 45mhz filter
  (now below the carrier due to sideband inversion from the high side VFO)
  would be 56995000-11998000 = 44997000 hz
  With clk1 for LSB of 32995000 hz, the center of that sideband within the 45mhz filter
  (now above the carrier due to sideband inversion from the high side VFO)
  would be 32995000+11998000 = 44993000 hz.


And I flipped the arithmetic at the wrong spot in these formulas:

>  The display shows the frequency of the suppressed carrier, always easy enough to compute:
>      For USB, it's   VFO-(clk1-BFO)
>      For LSB, it's   VFO-(clk1+BFO) 

Those two formulas should read:
 
     For USB, it's   VFO-(clk1-BFO)
     For LSB, it's   VFO-(clk1+BFO) 


Jerry, KE7ER

On Sat, Mar 10, 2018 at 11:36 pm, Jerry Gaffke wrote:
I think Gerald's complaint about USB sounding different than LSB winds up being due to
a USB signal going through the 45mhz filter a few khz away from where an LSB signal does. 
Gerald was using Ian's code which I have not yet looked over.
I assume Ian borrowed numbers from the original uBitx code.
Here's my argument:

The original uBitx code has the BFO at
    #define INIT_USB_FREQ   (11996500l)
and uses these frequencies for clk1:
    #define SECOND_OSC_USB (56995000l)
    #define SECOND_OSC_LSB (32995000l)

The 12mhz filter is passing audio between roughly 500 and 2500 hz in its upper sideband,
so the 12mhz filter is probably centered around 11996500 + (500+2500)/2 = 1199800 hz.

With a clk1 for USB of 56995000 hz, the center of that upper sideband in the 45mhz filter
would be 56995000-11998000 = 44997000 hz
With clk1 for LSB of 32995000 hz, the center of that lower sideband in the 45mhz filter
would be 32995000+11998000 = 44993000 hz.

That's a 4khz difference in where the center of the sideband of interest got placed
within the 45mhz crystal filter passband. 

Assuming the the 45mhz crystal filter is truly centered at 44.995mhz as the notes in the code suggest,
then I figure that values of 56993000 hz and 32997000 hz should be optimal for clk1.

If the 45mhz crystal filter sweeps out to be somewhere else, then add the difference to those two figures.
For example, if the center is found to be at 44.997mhz (so 2khz higher) then the two figures for clk1
should be 56995000 hz and 32999000 hz.


Regarding Tim's writup:

> When you are talking about adjusting the BFO I assume you are talking about adjusting CLK1.

No, we are talking about adjusting the BFO.
When adjusting the BFO, we should move the VFO to get us back to the displayed frequency.
The display shows the frequency of the suppressed carrier, always easy enough to compute:
    For USB, it's   VFO-(clk1-BFO)
    For LSB, it's   VFO+(clk1-BFO) 
where VFO is clk2, and BFO is clk0.

RIT allows a different VFO setting on receive than transmit.
This IF-Shift thing apparently allows a different BFO setting (with attendant VFO correction) on receive than transmit.

So IF-Shift will change what part of the sideband the 12mhz filter will capture (and thus capture a different range of audio frequencies) 
but does not change the frequency of the suppressed carrier that we are tuned to.

CW is a bit different, but easy enough.

Jerry, KE7ER 

Jerry Gaffke
 

Yes, the tone of the CW signal should not change if IF-Shift (and/or BFO-Adjust,
whatever you want to call it) is implemented correctly by changing both 
the BFO and the VFO as mentioned in post 44182.

The original uBitx code implemented BFO-Adjust by only moving the BFO,
so the CW tone did change, and SSB speech becomes unnatural/unintelligible.
I have no idea what the various new versions of the code do these days.

Moving clk1 as somebody suggested a few posts back won't work,
we must adjust the 12mhz BFO (equal to the incoming suppressed carrier)
relative to the 12mhz filter passband.
 
Jerry, KE7ER


On Sun, Mar 11, 2018 at 07:37 am, Tim Gorman wrote:
If you are listening to a CW signal then moving the IF Shift doesn't
change the tone of the CW signal at all. You are just moving the
passband. That can change the sound of a SSB signal because you are
removing some of the received audio along with the interfering signal.
Just like cutting the highs or lows with a treble/bass tone control.

Jerry Gaffke
 

Good catch.
My excuse for last night was it was too late.
Now it's too early.

The original (and incorrect) formulas from post 44182 was this:
    For USB, it's   VFO-(clk1-BFO)
    For LSB, it's   VFO+(clk1-BFO) 

The correct formulas are the duplicated ones that you spotted:
     For USB, it's   VFO-(clk1-BFO)
     For LSB, it's   VFO-(clk1+BFO) 

Thanks,
Jerry, KE7ER


On Sun, Mar 11, 2018 at 07:57 am, Rod Self wrote:

Jerry,

 Huh? The formula correction at the bottom seems to be
no-change.  Is that what you meant?

Rod KM6SN

Tim Gorman
 

Allard,

I don't think I agree with you. PBT and "clariier" are two different
things.

A "clarifer" or incremental tuning control is only useful for tuning an
off-frequency signal. The BFO must be at the suppressed carrier
frequency for proper detection of a SSB signal. If you deviate from that
frequency then the detected audio becomes distorted, the old "donald
duck" sound spoken of by the old-timers. One of my first
ham-band receivers was an old RME-4350, 1950's vintage. It had a "BFO"
control which was really useful on SSB because in a round-table not all
transmitters could be set to the exact same frequency - resolution of
1kc was pretty good! The BFO could be used to tune everyone in properly,
in essence it was what is today called an "receiver incremental tuning"
control.

Passband tuning (or IF Shift) does not impact the relationship of the
BFO to the suppressed carrier at all. You could do the IF Shift by
changing CLK1 in order to shift where the signal impacts the 12Mhz
passband of the SSB filter but CLK0 would still have to maintain the
same relationship to CLK2 in order to demodulate the signal properly.

tim ab0wr

On Sun, 11 Mar 2018 01:09:24 +0100
"Allard PE1NWL" <@pe1nwl> wrote:

Jerry,

I believe it works in a similar way as the PBT (or "clarifier")
function in the Raduino v2 software for Bitx40.
https://github.com/amunters/bitx40-raduino-v2/blob/master/PBT.png
It allows the user to slightly shift the BFO frequency from the
frontpanel (only during RX of course).
It's not IF shift in its true sense, but the behaviour is quite
similar. I have the impression that not many BitX40 builders actually
installed this mod, which has always surprised me as I personally
find it a very useful feature.

73 Allard PE1NWL

On Sun, March 11, 2018 00:52, Jerry Gaffke via Groups.Io wrote:
OK, so IF-Shift is just a BFO offset (relative to the crystal filter
passband) 
that is for receive only, the transmit BFO offset generally stays
put. Makes sense.

I went off into the weeds there because Gerald's original query
stated that
 In LSB I can adjust the received sound with the IF-Shift with a
very pleasing effect, but this does not work the same with USB.
Sounded like there was something more going on.
But could be just that the code didn't quite handle the USB case
correctly.

Yes, eventually I'll move on to try some of the newer software.
But for now have my hands full with other projects.

Jerry  

On Sat, Mar 10, 2018 at 02:49 pm, Mike Woods wrote:


Most commercial rigs have an IF Shift or Passband Tuning (PBT)
control. 
This control can help with removal of QRM on receive ( e.g.by (
http://e.g.by ) eliminating a strong carrier or another station on
the edge
of the passband by shifting the passband up or down by a few 100
Hz. It can also compensate for a poorly adjusted frequency
response on a signal that is being received (too bassy or too
trebly).  
Ian’s software implements just such a control.  It functions in
a similar
manner to the BFO calibration routine, in fact, but unlike the
calibration
function, it should only operate on RX. This was the bug - it
didn’t turn
off on TX.  I checked on my uBITx and found the same problem here.
 
If you haven’t tried the KD8CEC firmware you should.  It has a
number of
other worthwhile software features!
 


Willy
 

Yes Allard, I agree, It is a very effective and simple mod regardless of what you call it. I have been using it since your release and find it one of the best features of my Bitx.
Willy

On Sat, Mar 10, 2018 at 7:09 PM, Allard PE1NWL <pe1nwl@...> wrote:
Jerry,

I believe it works in a similar way as the PBT (or "clarifier") function
in the  Raduino v2 software for Bitx40.
https://github.com/amunters/bitx40-raduino-v2/blob/master/PBT.png
It allows the user to slightly shift the BFO frequency from the frontpanel
(only during RX of course).
It's not IF shift in its true sense, but the behaviour is quite similar.
I have the impression that not many BitX40 builders actually installed
this mod, which has always surprised me as I personally find it a very
useful feature.

73 Allard PE1NWL

On Sun, March 11, 2018 00:52, Jerry Gaffke via Groups.Io wrote:
> OK, so IF-Shift is just a BFO offset (relative to the crystal filter
> passband) 
> that is for receive only, the transmit BFO offset generally stays put.
> Makes sense.
>
> I went off into the weeds there because Gerald's original query stated
> that
>> In LSB I can adjust the received sound with the IF-Shift with a
>> very pleasing effect, but this does not work the same with USB.
>
> Sounded like there was something more going on.
> But could be just that the code didn't quite handle the USB case
> correctly.
>
> Yes, eventually I'll move on to try some of the newer software.
> But for now have my hands full with other projects.
>
> Jerry  
>
> On Sat, Mar 10, 2018 at 02:49 pm, Mike Woods wrote:
>
>>
>> Most commercial rigs have an IF Shift or Passband Tuning (PBT)
>> control. 
>> This control can help with removal of QRM on receive ( e.g.by (
>> http://e.g.by ) eliminating a strong carrier or another station on the
>> edge
>> of the passband by shifting the passband up or down by a few 100 Hz. It
>> can also compensate for a poorly adjusted frequency response on a signal
>> that is being received (too bassy or too trebly). 
>>  
>> Ian’s software implements just such a control.  It functions in a
>> similar
>> manner to the BFO calibration routine, in fact, but unlike the
>> calibration
>> function, it should only operate on RX. This was the bug - it didn’t
>> turn
>> off on TX.  I checked on my uBITx and found the same problem here.
>>  
>> If you haven’t tried the KD8CEC firmware you should.  It has a number
>> of
>> other worthwhile software features!
>>  
>>
>





Michael Shreeve
 

Hey guys, very important conversation. Most of the "principles" are here, Ashhar is sleeping hopefully, so, I wouldn't think of adding much other than to say that I have seen very illustrative conversations about this in the past. Here is one https://youtu.be/IELJwapv5qs And, in order to be able to SEE exactly what was going on here, I have found an Android app , audio spectrum analyzer. Called Spectroid, at your android app store. Amazing what it looks like (especially when phone is sideways ) but not sure it would help anyone ? Oh, and I've also spent some time actually measuring the different oscillators frequencies (Nice to see just exactly what the software is changing) , working on some calibration procedures (of my counter and the uBITX) , and plan to compare to a uBITX using a Raduino,  which sounds not so good. Thanks.  Carefully setting up the standards so I will be ready. 

Tim Gorman
 

Jerry,

This is a very complicated subject. The BFO, i.e. CLK0 *has* to be at
the suppressed carrier frequency in order to properly demodulate the
signal.

In order to do PBT you would have to shift three variables, CLK2, CLK0,
and the indicated frequency.

Conditions: 10Mhz suppressed carrier
CLK2 at 35Mhz to shift signal to 45Mhz
CLK1 at 33Mzh to shift signal to 12Mhz
CLK0 at 12Mhz to demodulate the signal
Freq Indicator at 10Mhz

Assume we want to shift the signal 500hz to get rid of an interfering
carrier.

Conditions: 10Mhz suppressed carrier
CLK2 at 35,000,500hz to shift signal to 45,000,500hz
CLK1 at 33Mhz to shift signal to 12,000,500hz
CLK0 at 12,000,500hz to properly demodulate the signal
Freq Indicator at 10Mhz
This would move the interfering carrier up and out of the passband.

I agree this would implement PBT or IF Shift.

This is not, however, what was being described. Moving CLK0 is truly
incremental tuning without the frequency indicator being changed. When
you move the BFO without also moving CLK2 you are changing what
frequency is considered as the suppressed carrier frequency. It will
change the relationship of all demodulated audio. If you are listening
to a CW carrier the pitch of the CW carrier will change as you change
the BFO (i.e. CLK0) by itself. This is exactly what is needed to tune
in a signal that is slightly off frequency.

Let's consider what happens if you change CLK1 and CLK0.

Conditions:
(same as original, 10Mhz Suppressed cxr,CLK2 =35Mhz, CLK1=33Mhz,
CLK0=12Mhz)

New Conditions: (move passband 500hz)
10Mhz suppressed carrier
CLK2=35Mhz to shift signal to 45Mhz
CLK1=32,999,500hz to shift signal to 12,000,500hz
CLK0=12,000,500hz to properly demodulate the signal
Frequency Indicator at 10Mhz

Same result. You can obtain PBT by changing 2 variables. You can't do
it by changing just one.

Does the ubitx software maintain a CLK0(USB) and a different CLK0(LSB)?
If not then changing the BFO (CLK0) by itself will result in an
asymmetric USB and LSB since the actual suppressed carrier freq now has
an offset.

This is what was being described.

tim ab0wr




On Sat, 10 Mar 2018 23:36:21 -0800
"Jerry Gaffke via Groups.Io" <jgaffke=yahoo.com@groups.io> wrote:

Regarding Tim's writup:

When you are talking about adjusting the BFO I assume you are
talking about adjusting CLK1.
No, we are talking about adjusting the BFO.
When adjusting the BFO, we should move the VFO to get us back to the
displayed frequency. The display shows the frequency of the
suppressed carrier, always easy enough to compute: For USB, it's
 VFO-(clk1-BFO) For LSB, it's   VFO+(clk1-BFO) 
where VFO is clk2, and BFO is clk0.

RIT allows a different VFO setting on receive than transmit.
This IF-Shift thing apparently allows a different BFO setting (with
attendant VFO correction) on receive than transmit.

So IF-Shift will change what part of the sideband the 12mhz filter
will capture (and thus capture a different range of audio
frequencies) but does not change the frequency of the suppressed
carrier that we are tuned to.

CW is a bit different, but easy enough.

Jerry, KE7ER

Vince Vielhaber
 

Did you even read what I wrote? If so, did you comprehend? You repeated the same thing I wrote.

Vince.

On 03/11/2018 10:37 AM, Tim Gorman wrote:
Vince,

If you are listening to a CW signal then moving the IF Shift doesn't
change the tone of the CW signal at all. You are just moving the
passband. That can change the sound of a SSB signal because you are
removing some of the received audio along with the interfering signal.
Just like cutting the highs or lows with a treble/bass tone control.

tim ab0wr

On Sat, 10 Mar 2018 21:07:17 -0500
"Vince Vielhaber" <vev@...> wrote:

IF Shift is supposed to shift the signal thru the passband without
changing the frequency. So if you're listening to 3930 and there are
signals on 3928 (it happens daily) at the same time, you can use the
IF Shift to move the signals on 3928 out of the passband. If affects
the sound of the desired signal like a tone control but that's a side
effect of the action.

Vince.



On 03/10/2018 09:02 PM, Ronald Pfeiffer via Groups.Io wrote:
Yes I was confused a while back when Ian announced his IF shift.
The code looked just like our RIT. Our RIT displays the freq on
bottom line and the line above displays the plus/minus offset as
you move the encoder.

rOn



------------------------------------------------------------------------
*From:* Tim Gorman <tgorman2@...>
*To:* BITX20@groups.io
*Sent:* Saturday, March 10, 2018 8:24 PM
*Subject:* Re: [BITX20] #uBITX Firmware KD8CEC - IF-Shift etc.

I wonder if we need to define some terms here. Passband tuning and
IF Shift typically move the *filter*, not the carrier. The carrier
will remained tuned to the same frequency when adjusting this. For
instance, if you use IF Shift when listening to a CW signal the
tone of the CW signal should not change. You can move the filter
bandwidth up or down to eliminate an interfering carrier that is
close to the desired frequency.

What you are describing is more like an Incremental Tuning, e.g.
RIT or XIT. When you move the BFO you move the carrier frequency,
not the filter bandwidth.

Ideally the BFO would be set to replicate the suppressed carrier
frequency. The filter then determines what is heard.

The ubitx uses a 12Mhz crystal filter. I don't know its bandwidth or
what the actual absolute frequencies are. I haven't had a chance to
run a spectrum analyzer against mine. Let's assume it has a 2400hz
bandwidth and goes from 12,000,300hz to 12,002,700hz.

If you want to listen to a signal at 10Mhz then CLK2 should be
tuned to 55Mhz to generate the 45Mhz signal the first IF needs.

CLK1 should then be set to generate a 12Mhz signal, i.e. 33Mhz. For
an USB signal we should then see frequencies of 12Mhz to 12.003Mhz
(or whatever the transmitted bandwidth is, e.g. 0-3000hz). You will
then see frequencies of 12.0003Mhz to 12.0027Mhz out of the filter.

This is how an ideal receiver would work.

When you are talking about adjusting the BFO I assume you are
talking about adjusting CLK1. If you adjust CLK1 to move the actual
suppressed carrier frequency somewhere else in the filter bandwidth
then your frequency indication is going to be off. What should be a
10Mhz signal is going to look like something else.

This will cause an asymmetric USB and LSB response and frequency
indication.

If you want to change the BFO frequency on the fly then it should be
understood as being an incremental tuning so you can remember what
the base frequency should be.

Now each filter is probably going to have a different actual
physical, absolute bandpass. The BFO will have to be adjusted to
allow for this but the frequency indication needs to be adjusted as
well to match. It should be a fixed reference, not a variable one.

Your transmitted frequency has to be offset from the CW-tone if it
is to be zero beat with the received signal. If it isn't then
you'll never be zero beat. I'm assuming that the CWL and CWU
frequencies are indicating a frequency CW-tone away from the actual
transmitting frequency. That may be because your receive BFO
frequency isn't set to indicate actual carrier frequency.

I didn't mean for this to get so complicated but it isn't an easy
subject.

tim ab0wr


On Sun, 11 Mar 2018 01:08:55 +0100
"ge_clipboard" <clipboard@... <mailto:clipboard@...>>
wrote:
Hi All

Many thanks for all the response concerning the BFO adjustement and
about using the IF-shift. I have been playing around with the BFO
setting while monitoring myself on another transceiver but as I’m
not getting there where I really would like to, I returned to the
factory settings. Leastening to the transmitted LSB and USB on
another transceiver was never symetric, maybe the steps to set the
bfo are not fine enough to do this or I am making something wrong.

Yes, the IF-shift is often a very helpfull feature within crowded
bands and as Mike pointed out, it is also nice to be able to adjust
the sound of a ssb signal on receive. So, if this could be
corrected in the software would be very fine.

Another point I’ve noticed today while using CW, dx-cluster and CAT
to jump to a anounced station... When the CWL-, CWU-feature is
enabled, then the frequency is not spot on but offset by the amount
of the CW-Tone.

Nevertheless, this little rig is a joy to play with, especially
with all the added features by Ian‘s software.

Vy 73, Gerald - HB9CEY





Jerry Gaffke
 

I faintly disagree.  

Might work, but you are better off moving the VFO and the BFO, not clk1 and the BFO.
If moving clk1, you change where the signal we extract is hitting the 45mhz filter.

Faintly, because the 45mhz filter is wider than the 12mhz filter.
Though not terribly wide, and probably not terribly flat either.
    http://www.hy-q.com.au/pdf/10120049.pdf
Moving the VFO is just as easy as moving clk1, and should give at least marginally
better results.

Jerry, KE7ER 


On Sun, Mar 11, 2018 at 08:12 am, Tim Gorman wrote:
You could do the IF Shift by
changing CLK1 in order to shift where the signal impacts the 12Mhz
passband of the SSB filter but CLK0 would still have to maintain the
same relationship to CLK2 in order to demodulate the signal properly.

Tim Gorman
 

Wow! Testy, aren't we?

I know I said basically the same thing as you. I just explained it a
little differently!

It was not meant to be a criticism of what you wrote!

tim ab0wr

On Sun, 11 Mar 2018 12:16:05 -0400
"Vince Vielhaber" <vev@...> wrote:

Did you even read what I wrote? If so, did you comprehend? You
repeated the same thing I wrote.

Vince.

On 03/11/2018 10:37 AM, Tim Gorman wrote:
Vince,

If you are listening to a CW signal then moving the IF Shift doesn't
change the tone of the CW signal at all. You are just moving the
passband. That can change the sound of a SSB signal because you are
removing some of the received audio along with the interfering
signal. Just like cutting the highs or lows with a treble/bass tone
control.

tim ab0wr

On Sat, 10 Mar 2018 21:07:17 -0500
"Vince Vielhaber" <vev@...> wrote:

IF Shift is supposed to shift the signal thru the passband without
changing the frequency. So if you're listening to 3930 and there
are signals on 3928 (it happens daily) at the same time, you can
use the IF Shift to move the signals on 3928 out of the passband.
If affects the sound of the desired signal like a tone control but
that's a side effect of the action.

Vince.



On 03/10/2018 09:02 PM, Ronald Pfeiffer via Groups.Io wrote:
Yes I was confused a while back when Ian announced his IF shift.
The code looked just like our RIT. Our RIT displays the freq on
bottom line and the line above displays the plus/minus offset as
you move the encoder.

rOn



------------------------------------------------------------------------
*From:* Tim Gorman <tgorman2@...>
*To:* BITX20@groups.io
*Sent:* Saturday, March 10, 2018 8:24 PM
*Subject:* Re: [BITX20] #uBITX Firmware KD8CEC - IF-Shift etc.

I wonder if we need to define some terms here. Passband tuning and
IF Shift typically move the *filter*, not the carrier. The carrier
will remained tuned to the same frequency when adjusting this. For
instance, if you use IF Shift when listening to a CW signal the
tone of the CW signal should not change. You can move the filter
bandwidth up or down to eliminate an interfering carrier that is
close to the desired frequency.

What you are describing is more like an Incremental Tuning, e.g.
RIT or XIT. When you move the BFO you move the carrier frequency,
not the filter bandwidth.

Ideally the BFO would be set to replicate the suppressed carrier
frequency. The filter then determines what is heard.

The ubitx uses a 12Mhz crystal filter. I don't know its bandwidth
or what the actual absolute frequencies are. I haven't had a
chance to run a spectrum analyzer against mine. Let's assume it
has a 2400hz bandwidth and goes from 12,000,300hz to 12,002,700hz.

If you want to listen to a signal at 10Mhz then CLK2 should be
tuned to 55Mhz to generate the 45Mhz signal the first IF needs.

CLK1 should then be set to generate a 12Mhz signal, i.e. 33Mhz.
For an USB signal we should then see frequencies of 12Mhz to
12.003Mhz (or whatever the transmitted bandwidth is, e.g.
0-3000hz). You will then see frequencies of 12.0003Mhz to
12.0027Mhz out of the filter.

This is how an ideal receiver would work.

When you are talking about adjusting the BFO I assume you are
talking about adjusting CLK1. If you adjust CLK1 to move the
actual suppressed carrier frequency somewhere else in the filter
bandwidth then your frequency indication is going to be off. What
should be a 10Mhz signal is going to look like something else.

This will cause an asymmetric USB and LSB response and frequency
indication.

If you want to change the BFO frequency on the fly then it should
be understood as being an incremental tuning so you can remember
what the base frequency should be.

Now each filter is probably going to have a different actual
physical, absolute bandpass. The BFO will have to be adjusted to
allow for this but the frequency indication needs to be adjusted
as well to match. It should be a fixed reference, not a variable
one.

Your transmitted frequency has to be offset from the CW-tone if it
is to be zero beat with the received signal. If it isn't then
you'll never be zero beat. I'm assuming that the CWL and CWU
frequencies are indicating a frequency CW-tone away from the
actual transmitting frequency. That may be because your receive
BFO frequency isn't set to indicate actual carrier frequency.

I didn't mean for this to get so complicated but it isn't an easy
subject.

tim ab0wr


On Sun, 11 Mar 2018 01:08:55 +0100
"ge_clipboard" <clipboard@...
<mailto:clipboard@...>> wrote:
Hi All

Many thanks for all the response concerning the BFO adjustement
and about using the IF-shift. I have been playing around with
the BFO setting while monitoring myself on another transceiver
but as I’m not getting there where I really would like to, I
returned to the factory settings. Leastening to the transmitted
LSB and USB on another transceiver was never symetric, maybe the
steps to set the bfo are not fine enough to do this or I am
making something wrong.

Yes, the IF-shift is often a very helpfull feature within crowded
bands and as Mike pointed out, it is also nice to be able to
adjust the sound of a ssb signal on receive. So, if this could be
corrected in the software would be very fine.

Another point I’ve noticed today while using CW, dx-cluster and
CAT to jump to a anounced station... When the CWL-, CWU-feature
is enabled, then the frequency is not spot on but offset by the
amount of the CW-Tone.

Nevertheless, this little rig is a joy to play with, especially
with all the added features by Ian‘s software.

Vy 73, Gerald - HB9CEY






Vince Vielhaber
 

Well I'm used to you criticizing what I write as if you don't understand it.

Vince.

On 03/11/2018 12:21 PM, Tim Gorman wrote:
Wow! Testy, aren't we?

I know I said basically the same thing as you. I just explained it a
little differently!

It was not meant to be a criticism of what you wrote!

tim ab0wr

On Sun, 11 Mar 2018 12:16:05 -0400
"Vince Vielhaber" <vev@...> wrote:

Did you even read what I wrote? If so, did you comprehend? You
repeated the same thing I wrote.

Vince.

On 03/11/2018 10:37 AM, Tim Gorman wrote:
Vince,

If you are listening to a CW signal then moving the IF Shift doesn't
change the tone of the CW signal at all. You are just moving the
passband. That can change the sound of a SSB signal because you are
removing some of the received audio along with the interfering
signal. Just like cutting the highs or lows with a treble/bass tone
control.

tim ab0wr

On Sat, 10 Mar 2018 21:07:17 -0500
"Vince Vielhaber" <vev@...> wrote:

IF Shift is supposed to shift the signal thru the passband without
changing the frequency. So if you're listening to 3930 and there
are signals on 3928 (it happens daily) at the same time, you can
use the IF Shift to move the signals on 3928 out of the passband.
If affects the sound of the desired signal like a tone control but
that's a side effect of the action.

Vince.



On 03/10/2018 09:02 PM, Ronald Pfeiffer via Groups.Io wrote:
Yes I was confused a while back when Ian announced his IF shift.
The code looked just like our RIT. Our RIT displays the freq on
bottom line and the line above displays the plus/minus offset as
you move the encoder.

rOn



------------------------------------------------------------------------
*From:* Tim Gorman <tgorman2@...>
*To:* BITX20@groups.io
*Sent:* Saturday, March 10, 2018 8:24 PM
*Subject:* Re: [BITX20] #uBITX Firmware KD8CEC - IF-Shift etc.

I wonder if we need to define some terms here. Passband tuning and
IF Shift typically move the *filter*, not the carrier. The carrier
will remained tuned to the same frequency when adjusting this. For
instance, if you use IF Shift when listening to a CW signal the
tone of the CW signal should not change. You can move the filter
bandwidth up or down to eliminate an interfering carrier that is
close to the desired frequency.

What you are describing is more like an Incremental Tuning, e.g.
RIT or XIT. When you move the BFO you move the carrier frequency,
not the filter bandwidth.

Ideally the BFO would be set to replicate the suppressed carrier
frequency. The filter then determines what is heard.

The ubitx uses a 12Mhz crystal filter. I don't know its bandwidth
or what the actual absolute frequencies are. I haven't had a
chance to run a spectrum analyzer against mine. Let's assume it
has a 2400hz bandwidth and goes from 12,000,300hz to 12,002,700hz.

If you want to listen to a signal at 10Mhz then CLK2 should be
tuned to 55Mhz to generate the 45Mhz signal the first IF needs.

CLK1 should then be set to generate a 12Mhz signal, i.e. 33Mhz.
For an USB signal we should then see frequencies of 12Mhz to
12.003Mhz (or whatever the transmitted bandwidth is, e.g.
0-3000hz). You will then see frequencies of 12.0003Mhz to
12.0027Mhz out of the filter.

This is how an ideal receiver would work.

When you are talking about adjusting the BFO I assume you are
talking about adjusting CLK1. If you adjust CLK1 to move the
actual suppressed carrier frequency somewhere else in the filter
bandwidth then your frequency indication is going to be off. What
should be a 10Mhz signal is going to look like something else.

This will cause an asymmetric USB and LSB response and frequency
indication.

If you want to change the BFO frequency on the fly then it should
be understood as being an incremental tuning so you can remember
what the base frequency should be.

Now each filter is probably going to have a different actual
physical, absolute bandpass. The BFO will have to be adjusted to
allow for this but the frequency indication needs to be adjusted
as well to match. It should be a fixed reference, not a variable
one.

Your transmitted frequency has to be offset from the CW-tone if it
is to be zero beat with the received signal. If it isn't then
you'll never be zero beat. I'm assuming that the CWL and CWU
frequencies are indicating a frequency CW-tone away from the
actual transmitting frequency. That may be because your receive
BFO frequency isn't set to indicate actual carrier frequency.

I didn't mean for this to get so complicated but it isn't an easy
subject.

tim ab0wr


On Sun, 11 Mar 2018 01:08:55 +0100
"ge_clipboard" <clipboard@...
<mailto:clipboard@...>> wrote:
Hi All

Many thanks for all the response concerning the BFO adjustement
and about using the IF-shift. I have been playing around with
the BFO setting while monitoring myself on another transceiver
but as I’m not getting there where I really would like to, I
returned to the factory settings. Leastening to the transmitted
LSB and USB on another transceiver was never symetric, maybe the
steps to set the bfo are not fine enough to do this or I am
making something wrong.

Yes, the IF-shift is often a very helpfull feature within crowded
bands and as Mike pointed out, it is also nice to be able to
adjust the sound of a ssb signal on receive. So, if this could be
corrected in the software would be very fine.

Another point I’ve noticed today while using CW, dx-cluster and
CAT to jump to a anounced station... When the CWL-, CWU-feature
is enabled, then the frequency is not spot on but offset by the
amount of the CW-Tone.

Nevertheless, this little rig is a joy to play with, especially
with all the added features by Ian‘s software.

Vy 73, Gerald - HB9CEY







Jerry Gaffke
 

Tim,

Good, looks like you now agree with my ost 44182 that moving the VFO + BFO
is a better solution than moving clk1 + BFO.

As I stated in post 44182, the original uBitx code only moves the BFO when doing a BFO Adjust,
and you agree that this is not ideal.

Is there anything in post 44182 (as slightly amended in 44196 and 44200) that you disagree with?


You state:
>  Does the ubitx software maintain a CLK0(USB) and a different CLK0(LSB)?

No, the BFO is always below the 12mhz filter passband, if above then harmonics beat with an oscillator on the Nano.
As stated in post 44182.

>  If not then changing the BFO (CLK0) by itself will result in an
>  asymmetric USB and LSB since the actual suppressed carrier freq now has
>  an offset.

I guess this agrees with what I was saying in post 44182, though it's not terribly clear
exactly what asymmetry or exactly what offset you are referring to.
There's a bunch of contenders here.
Yes, changing only the BFO when trying to listen to a signal is generally a bad idea.

Jerry, KE7ER


On Sun, Mar 11, 2018 at 09:06 am, Tim Gorman wrote:
Jerry,

This is a very complicated subject. The BFO, i.e. CLK0 *has* to be at
the suppressed carrier frequency in order to properly demodulate the
signal.

In order to do PBT you would have to shift three variables, CLK2, CLK0,
and the indicated frequency.

Conditions: 10Mhz suppressed carrier
CLK2 at 35Mhz to shift signal to 45Mhz
CLK1 at 33Mzh to shift signal to 12Mhz
CLK0 at 12Mhz to demodulate the signal
Freq Indicator at 10Mhz

Assume we want to shift the signal 500hz to get rid of an interfering
carrier.

Conditions: 10Mhz suppressed carrier
CLK2 at 35,000,500hz to shift signal to 45,000,500hz
CLK1 at 33Mhz to shift signal to 12,000,500hz
CLK0 at 12,000,500hz to properly demodulate the signal
Freq Indicator at 10Mhz
This would move the interfering carrier up and out of the passband.

I agree this would implement PBT or IF Shift.

This is not, however, what was being described. Moving CLK0 is truly
incremental tuning without the frequency indicator being changed. When
you move the BFO without also moving CLK2 you are changing what
frequency is considered as the suppressed carrier frequency. It will
change the relationship of all demodulated audio. If you are listening
to a CW carrier the pitch of the CW carrier will change as you change
the BFO (i.e. CLK0) by itself. This is exactly what is needed to tune
in a signal that is slightly off frequency.

Let's consider what happens if you change CLK1 and CLK0.

Conditions:
(same as original, 10Mhz Suppressed cxr,CLK2 =35Mhz, CLK1=33Mhz,
CLK0=12Mhz)

New Conditions: (move passband 500hz)
10Mhz suppressed carrier
CLK2=35Mhz to shift signal to 45Mhz
CLK1=32,999,500hz to shift signal to 12,000,500hz
CLK0=12,000,500hz to properly demodulate the signal
Frequency Indicator at 10Mhz

Same result. You can obtain PBT by changing 2 variables. You can't do
it by changing just one.

Does the ubitx software maintain a CLK0(USB) and a different CLK0(LSB)?
If not then changing the BFO (CLK0) by itself will result in an
asymmetric USB and LSB since the actual suppressed carrier freq now has
an offset.

This is what was being described.

tim ab0wr

Jerry Gaffke
 

Tim,

I think I now understand the offset you were referring to.
That's a good point, and this might be key to Gerald's problem
of hearing different audio on USB than LSB.

The answer, I think, is to keep the 2000 hz slice of the signal we are receiving
centered on the passband of the 45mhz filter.
As described in post 44182, the original uBitx code moves that slice by 4khz when we
switch from LSB to USB, rather significant given that in some versions the 45mhz crystal filter
can have a 3db passband of +/- 3.75khz.   Post 44182 proposes new values for clk1
that should fix the issue.

I first wrote a much longer version of post 44182, spelling out exactly where the
carriers and sidebands wind up at each stage in the rig for both LSB and USB cases,
and how and when and why the sidebands get inverted by the two mixers.
If 44182 gets vetted here in the forum, I'll post that longer version of what I think is going on.

And someday I should dig out my uBitx and see if my solution works.
Maybe even get it on the air.   ;-)

Jerry, KE7ER


On Sun, Mar 11, 2018 at 09:40 am, Jerry Gaffke wrote:
You state:
>  Does the ubitx software maintain a CLK0(USB) and a different CLK0(LSB)?

No, the BFO is always below the 12mhz filter passband, if above then harmonics beat with an oscillator on the Nano.
As stated in post 44182.

>  If not then changing the BFO (CLK0) by itself will result in an
>  asymmetric USB and LSB since the actual suppressed carrier freq now has
>  an offset.

I guess this agrees with what I was saying in post 44182, though it's not terribly clear
exactly what asymmetry or exactly what offset you are referring to.
There's a bunch of contenders here.
Yes, changing only the BFO when trying to listen to a signal is generally a bad idea.

Allard PE1NWL
 

Hi Tim,

yes, PBT and "clarifier" are indeed two different things.

When I implemented this functionality in the Raduino v2 sketch for BitX40,
I initially called it "clarifier", however later I realised this was not
the correct term. I later renamed it to Pass Band Tuning as I believe that
is more appropriate.

Whatever you call it, technically it allows the operator to shift the BFO
frequency during RX, and at the same time the VFO frequency is shifted by
the same amount (so that the relationship of the BFO to the suppressed
carrier is not affected).

If you still have a BitX40, try it out this simple mod and you will be
amazed about this feature.

https://github.com/amunters/bitx40-raduino-v2/blob/master/README.md

73 Allard PE1NWL

On Sun, March 11, 2018 16:11, Tim Gorman wrote:
Allard,

I don't think I agree with you. PBT and "clariier" are two different
things.

A "clarifer" or incremental tuning control is only useful for tuning an
off-frequency signal. The BFO must be at the suppressed carrier
frequency for proper detection of a SSB signal. If you deviate from that
frequency then the detected audio becomes distorted, the old "donald
duck" sound spoken of by the old-timers. One of my first
ham-band receivers was an old RME-4350, 1950's vintage. It had a "BFO"
control which was really useful on SSB because in a round-table not all
transmitters could be set to the exact same frequency - resolution of
1kc was pretty good! The BFO could be used to tune everyone in properly,
in essence it was what is today called an "receiver incremental tuning"
control.

Passband tuning (or IF Shift) does not impact the relationship of the
BFO to the suppressed carrier at all. You could do the IF Shift by
changing CLK1 in order to shift where the signal impacts the 12Mhz
passband of the SSB filter but CLK0 would still have to maintain the
same relationship to CLK2 in order to demodulate the signal properly.

tim ab0wr

On Sun, 11 Mar 2018 01:09:24 +0100
"Allard PE1NWL" <@pe1nwl> wrote:

Jerry,

I believe it works in a similar way as the PBT (or "clarifier")
function in the Raduino v2 software for Bitx40.
https://github.com/amunters/bitx40-raduino-v2/blob/master/PBT.png
It allows the user to slightly shift the BFO frequency from the
frontpanel (only during RX of course).
It's not IF shift in its true sense, but the behaviour is quite
similar. I have the impression that not many BitX40 builders actually
installed this mod, which has always surprised me as I personally
find it a very useful feature.

73 Allard PE1NWL

On Sun, March 11, 2018 00:52, Jerry Gaffke via Groups.Io wrote:
OK, so IF-Shift is just a BFO offset (relative to the crystal filter
passband) 
that is for receive only, the transmit BFO offset generally stays
put. Makes sense.

I went off into the weeds there because Gerald's original query
stated that
 In LSB I can adjust the received sound with the IF-Shift with a
very pleasing effect, but this does not work the same with USB.
Sounded like there was something more going on.
But could be just that the code didn't quite handle the USB case
correctly.

Yes, eventually I'll move on to try some of the newer software.
But for now have my hands full with other projects.

Jerry  

On Sat, Mar 10, 2018 at 02:49 pm, Mike Woods wrote:


Most commercial rigs have an IF Shift or Passband Tuning (PBT)
control. 
This control can help with removal of QRM on receive ( e.g.by (
http://e.g.by ) eliminating a strong carrier or another station on
the edge
of the passband by shifting the passband up or down by a few 100
Hz. It can also compensate for a poorly adjusted frequency
response on a signal that is being received (too bassy or too
trebly).  
Ian’s software implements just such a control.  It
functions in
a similar
manner to the BFO calibration routine, in fact, but unlike the
calibration
function, it should only operate on RX. This was the bug - it
didn’t turn
off on TX.  I checked on my uBITx and found the same problem here.
 
If you haven’t tried the KD8CEC firmware you should.  It
has a
number of
other worthwhile software features!
 





Jerry Gaffke
 

Whoops, that did not get stated in post 44182.  My apologies.  (Was in the earlier draft mentioned in post 44228)
Has been discussed in the forum here several times, though that was a few thousand posts ago.


On Sun, Mar 11, 2018 at 09:40 am, Jerry Gaffke wrote:
No, the BFO is always below the 12mhz filter passband, if above then harmonics beat with an oscillator on the Nano.
As stated in post 44182.

Jerry Gaffke
 


So we have two knobs to twiddle during receive:
    RIT:  Change the tuning on receive only.
    PBT:  Change the tuning and the BFO, both in sync

This post suggests that "Clarify" is just another name for "RIT".
https://ham.stackexchange.com/questions/1467/how-is-clarifier-control-helpful

In post 44223, I said this, I still think it's right but am open to arguments:
>    Yes, changing only the BFO when trying to listen to a signal is generally a bad idea.

We need a PBT to set the default position of BFO relative to 12mhz filter passband during calibration.
We also need a receive only version, perhaps call it RI-PBT?
Then if the other end is tuned up for somebody with a high pitched voice
or if there is a nearby carrier that we wish to get rid of,
we can adjust our receiver to compensate without disturbing our transmission.

Jerry


On Sun, Mar 11, 2018 at 11:12 am, Allard PE1NWL wrote:
yes, PBT and "clarifier" are indeed two different things.

When I implemented this functionality in the Raduino v2 sketch for BitX40,
I initially called it "clarifier", however later I realised this was not
the correct term. I later renamed it to Pass Band Tuning as I believe that
is more appropriate.

Whatever you call it, technically it allows the operator to shift the BFO
frequency during RX, and at the same time the VFO frequency is shifted by
the same amount (so that the relationship of the BFO to the suppressed
carrier is not affected).

If you still have a BitX40, try it out this simple mod and you will be
amazed about this feature.

Michael Shreeve
 

Also, seems like Ashar, some time back, not sure he was talking about BITX40 or uBITX had said that the crystals used for these passbands were not always using quite the same frequency due to the fact that the folks he had making the crystals were not always providing accurate crystals ? He indicated that they would go through the crystals and match them for a group.  So , occasionally , if this is true, the passband of the filter could be different a kc or two ? A Vector Analyzer or tracking generator plus scope could verify this, but, you'd need access to a bunch of radios. 

Jerry Gaffke
 

Yes, the passband of the 12mhz filter can vary by rig.
The fix is using a PBT function within the configuration menu
to get the best audio on an LSB signal.

Could be that the 45mhz passband varies significantly by rig as well, making USB sound different than LSB.
So symptoms like what Gerald's original post to this thread describes.
If so, we need another configuration menu item to scoot around clk1 an equal amount for USB and LSB
as described in post 44182:
> If the 45mhz crystal filter sweeps out to be somewhere else, then add the difference to those two figures.
> For example, if the center is found to be at 44.997mhz (so 2khz higher) then the two figures for clk1
> should be 56995000 hz and 32999000 hz.
 
Should be able to do this all by ear if stuff is working but just off a bit in frequency.
If not working, then might need a diode RF probe or Nik's AD8307.
Plotting from the Raduino onto the USB host could be done as per post 32630.

Jerry, KE7ER


On Sun, Mar 11, 2018 at 11:54 am, Michael Shreeve wrote:
Also, seems like Ashar, some time back, not sure he was talking about BITX40 or uBITX had said that the crystals used for these passbands were not always using quite the same frequency due to the fact that the folks he had making the crystals were not always providing accurate crystals ? He indicated that they would go through the crystals and match them for a group.  So , occasionally , if this is true, the passband of the filter could be different a kc or two ? A Vector Analyzer or tracking generator plus scope could verify this, but, you'd need access to a bunch of radios. 

Jerry Gaffke
 

One more complication,

Post 44182 puts clk1 at 57995000 for USB and 32997000 for LSB.
They can both be adjusted up and down by some equal number of hz 
to compensate for differences in where the center of the 45mhz passband is.
But this all assumes that the center of the sideband of interest is 1500 hz
from the carrier.  

We may need to move the USB and LSB values for clk1 independently
when the PBT function changes that figure of 1500 hz by a few hundred Hz.
But the effect of a few hundred Hz should be far less noticeable
than the current difference of around 4khz. 

Good thing the math here is all just addition and subtraction, 
nothing complicated.  ;-)

Jerry, KE7ER


On Sun, Mar 11, 2018 at 12:16 pm, Jerry Gaffke wrote:
Yes, the passband of the 12mhz filter can vary by rig.
The fix is using a PBT function within the configuration menu
to get the best audio on an LSB signal.

Could be that the 45mhz passband varies significantly by rig as well, making USB sound different than LSB.
So symptoms like what Gerald's original post to this thread describes.
If so, we need another configuration menu item to scoot around clk1 an equal amount for USB and LSB
as described in post 44182:
> If the 45mhz crystal filter sweeps out to be somewhere else, then add the difference to those two figures.
> For example, if the center is found to be at 44.997mhz (so 2khz higher) then the two figures for clk1
> should be 56995000 hz and 32999000 hz.
 
Should be able to do this all by ear if stuff is working but just off a bit in frequency.
If not working, then might need a diode RF probe or Nik's AD8307.
Plotting from the Raduino onto the USB host could be done as per post 32630.

Jerry, KE7ER

Jerry Gaffke
 

Well, that was another thing that got pruned out the original document
before posting as 44182.

All that 44182 has to say is:
  When adjusting the BFO, we should move the VFO to get us back to the displayed frequency.
Doesn't say anything about what the original uBitx code does.
 
Sorry for any confusion.

Jerry


On Sun, Mar 11, 2018 at 09:40 am, Jerry Gaffke wrote:
As I stated in post 44182, the original uBitx code only moves the BFO when doing a BFO Adjust,
and you agree that this is not ideal.