Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Black Michael via wsjt-devel]

Try calibrating your audio with the paper that's at the top of my QRZ page.Used 
by hundreds (I'm not up to McDonald's numbers yet :-) of operators to get clean 
signals from their rigs and understand WSJT-X a bit 
better.https://www.qrz.com/db/W9MDB

de Mike W9MDB

 

On Thursday, June 27, 2019, 09:37:42 AM CDT, Reino Talarmo 
 wrote:  
 
 

>1.  The power spike problem can be “avoided” through keeping the xmtr power 
>low at the beginning of each cycle and then  gradually increasing it.  I have 
>bit of auxiliary code in Xojo which can do this, ramping power up during the 
>first 5 seconds of the cycle.  
Is it known what actually causes power spikes? WSJT-X as such is not the 
reason, but some control in radio adjusts audio path gain. If the radio audio 
path is set linear in the sense gain is the same independent of time, then 
there should not be any extra spike due to ‘stepwise’ start of audio tone. In 
most radios audio path gain is changed due to ALC actions. How fast ALC cuts 
off extra output power depends on the radio design; in worst case the ALC 
control may even ‘oscillate’.
 There could other reasons that also affect output power at the beginning of 
transmission, such as a drop of power supply voltage, may not be typical in 
modern radios; or a speech processing action. 
It would be interesting to see what kind of power spikes are generated, if any, 
when a stepwise audio is fed into radio at various power level (audio levels).

If the power needs to bring up slowly lasting 5 s, then that radio may not work 
properly at CW or voice. In any case it would degrade decoding performance. 
Perhaps ramp up time could be 5 ms to 50 ms.

73, Reino oh3ma

 

  
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Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Reino Talarmo]

>1.  The power spike problem can be “avoided” through keeping the xmtr power 
>low at the beginning of each cycle and then  gradually increasing it.  I have 
>bit of auxiliary code in Xojo which can do this, ramping power up during the 
>first 5 seconds of the cycle.  

Is it known what actually causes power spikes? WSJT-X as such is not the 
reason, but some control in radio adjusts audio path gain. If the radio audio 
path is set linear in the sense gain is the same independent of time, then 
there should not be any extra spike due to ‘stepwise’ start of audio tone. In 
most radios audio path gain is changed due to ALC actions. How fast ALC cuts 
off extra output power depends on the radio design; in worst case the ALC 
control may even ‘oscillate’.
There could other reasons that also affect output power at the beginning of 
transmission, such as a drop of power supply voltage, may not be typical in 
modern radios; or a speech processing action. 
It would be interesting to see what kind of power spikes are generated, if any, 
when a stepwise audio is fed into radio at various power level (audio levels).

If the power needs to bring up slowly lasting 5 s, then that radio may not work 
properly at CW or voice. In any case it would degrade decoding performance. 
Perhaps ramp up time could be 5 ms to 50 ms.

73, Reino oh3ma

 

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Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Ed Stokes]

I’ll try the new release and see how that works.  Thanks for the comment on 
decoding.  

>> How does Xojo open up a serial port that is already open?

An interesting question… 

No.  There is no splitter.  One connection through one RS232 port from a mac 
mini to an FTdx5000.  WSJT-X and my Xojo auxiliary app both run simultaneously 
on the mac. 

As far as the Xojo part goes, it’s very straightforward.  

There’s a serial object called theRadio.  When called to open, it opens, even 
if WSJT-X is running.  A timer is set, commands are sent to theRadio, replies 
are received and when the timer expires theRadio.close is called.  Once in a 
while there is a conflict but most of the time it works.  If theRadio.open 
generates an error, the app just waits an tries again.

So, for me the question is:  

Given that the serial port can be “seized” temporarily by another user, when 
does WSJT-X “care” and when does it not care?

73, Ed
W1KOK 
 


> On Jun 27, 2019, at 9:24 AM, Black Michael via wsjt-devel 
>  wrote:
> 
> I'd think that power supply spike might be better with the 2.1.0rc7 release 
> and the GFSK that it is doing since there's more of a ramp-up.
> 
> How does Xojo open up a serial port that is already open?  Are you using some 
> splitter?
> 
> I'd think ramping up power that slowly would risk the probability of your 
> signal being decoded.
> 
> de Mike W9MDB
> 
> 
> 
> 
> On Thursday, June 27, 2019, 08:18:47 AM CDT, Ed Stokes  
> wrote:
> 
> 
> A few more notes about this subject…
> 
> 
> 
> 1.  The power spike problem can be “avoided” through keeping the xmtr power 
> low at the beginning of each cycle and then  gradually increasing it.  I have 
> bit of auxiliary code in Xojo which can do this, ramping power up during the 
> first 5 seconds of the cycle.  
> 
> Would anyone care to comment on how this variable power would affect the FT8 
> throughput?
> 
> 
> 
> 2.  I would like to know more about how WSJT-X uses the serial port. 
> 
> By experimenting I found that Xojo can “grab” the serial port, interact 
> briefly with the radio, then drop the serial line and WSJT-X (with rare 
> exceptions) never notices.  
> 
> For example, my auxiliary app can open the same serial port which WSJT-X is 
> using to control the radio, send some commands to the radio, stay connected 
> for 100 ms. or so, then close that connection.  WSJT-X seems none the wiser 
> as long as the interruption is brief.
> 
> When does WSJT-X access the serial port and when is it possible for another 
> app to use it without causing a conflict?
> 
> 73, Ed
> W1KOK 
> 
>> On Apr 12, 2019, at 2:36 PM, Ed Stokes > > wrote:
>> 
>> Hi Bill,
>> 
>> Another extremely helpful comment.
>> 
>> As you may have noted in my previous post, I am not co-located with the 
>> equipment.
>> 
>> Is it possible to access this menu via the serial interface?
>> 
>> Otherwise, I will have to wait until next month when I am at home again and 
>> have physical access to the radio.
>> 
>> Thanks.
>> 
>> 73, Ed
>> W1KOK
>> 
>> 
>>> >From W8JI.com , maybe 5000 has similar adjustments. If 
>>> >the IF Transmit Gain
>>> was too high the 1000 would exhibit huge power spikes on key down or
>>> pressing the mike PTT button.
>>> 
>>> Transmit Gain Menus
>>> 
>>> The FT-1000 MK V  has hidden transmit gain menus. They are accessed by
>>> pushing and holding FAST and LOCK while turning the POWER switch on. Both
>>> of my MK V's  and every MK V serviced here has had the TX IF gain set too
>>> high. This causes first character clicks on CW and spits and splatter on
>>> SSB.  Here is how to correct the IF gain to prevent ALC clipping on leading
>>> edges of CW and voice:
>>> 
>>> Press and hold FAST and LOCK before and during initial POWER on.
>>> 
>>> Press FAST and ENT at the same time. You are now in the MENU's and the
>>> display should say "0-1 GrPI-cH".
>>> 
>>> Turn the VRF/MEM CH counter-clockwise to 9-2. The display should say "t iF
>>> - GA in" This is the transmit IF gain menu.
>>> 
>>> Turn the SUB VFO knob clockwise one position to  " t iF - 018". This is the
>>> 1.8MHz transmit IF gain.
>>> 
>>> Press the ALC/COMP meter selector until the bar graph says "ALC".  Set RF
>>> PWR knob to full power.
>>> 
>>> With the radio on CW and a 50 ohm dummy load connected, close the key and
>>> adjust the MAIN VFO-A knob until the ALC display is about 75-85% of full
>>> scale on the illuminated bar marked "ALC".
>>> 
>>> Press the next band button (3.5), make sure the radio is still  on CW, and
>>> turn the SUB VFO-B knob clockwise one band to "t iF - 035".
>>> 
>>> Again adjust MAIN VFO-A until ALC is at 75-85% of full scale.
>>> 
>>> Repeat this process through all bands.
>>> 
>>> Most radios I have tested require a setting of 2 to 4 on TX IF gain, with 3
>>> being the most common setting.
>>> 
>>> This change will reduce SSB bandwidth and distortion. It will also reduce
>>> keyclicks and annoying thumps on the leadin

Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Black Michael via wsjt-devel]

I'd think that power supply spike might be better with the 2.1.0rc7 release and 
the GFSK that it is doing since there's more of a ramp-up.
How does Xojo open up a serial port that is already open?  Are you using some 
splitter?
I'd think ramping up power that slowly would risk the probability of your 
signal being decoded.
de Mike W9MDB

 

On Thursday, June 27, 2019, 08:18:47 AM CDT, Ed Stokes  
wrote:  
 
 A few more notes about this subject…


1.  The power spike problem can be “avoided” through keeping the xmtr power low 
at the beginning of each cycle and then  gradually increasing it.  I have bit 
of auxiliary code in Xojo which can do this, ramping power up during the first 
5 seconds of the cycle.  
Would anyone care to comment on how this variable power would affect the FT8 
throughput?


2.  I would like to know more about how WSJT-X uses the serial port. 
By experimenting I found that Xojo can “grab” the serial port, interact briefly 
with the radio, then drop the serial line and WSJT-X (with rare exceptions) 
never notices.  
For example, my auxiliary app can open the same serial port which WSJT-X is 
using to control the radio, send some commands to the radio, stay connected for 
100 ms. or so, then close that connection.  WSJT-X seems none the wiser as long 
as the interruption is brief.
When does WSJT-X access the serial port and when is it possible for another app 
to use it without causing a conflict?
73, EdW1KOK 


On Apr 12, 2019, at 2:36 PM, Ed Stokes  wrote:
Hi Bill,
Another extremely helpful comment.
As you may have noted in my previous post, I am not co-located with the 
equipment.
Is it possible to access this menu via the serial interface?
Otherwise, I will have to wait until next month when I am at home again and 
have physical access to the radio.
Thanks.
73, EdW1KOK 


>From W8JI.com, maybe 5000 has similar adjustments. If the IF Transmit Gain
was too high the 1000 would exhibit huge power spikes on key down or
pressing the mike PTT button.

Transmit Gain Menus

The FT-1000 MK V  has hidden transmit gain menus. They are accessed by
pushing and holding FAST and LOCK while turning the POWER switch on. Both
of my MK V's  and every MK V serviced here has had the TX IF gain set too
high. This causes first character clicks on CW and spits and splatter on
SSB.  Here is how to correct the IF gain to prevent ALC clipping on leading
edges of CW and voice:

Press and hold FAST and LOCK before and during initial POWER on.

Press FAST and ENT at the same time. You are now in the MENU's and the
display should say "0-1 GrPI-cH".

Turn the VRF/MEM CH counter-clockwise to 9-2. The display should say "t iF
- GA in" This is the transmit IF gain menu.

Turn the SUB VFO knob clockwise one position to  " t iF - 018". This is the
1.8MHz transmit IF gain.

Press the ALC/COMP meter selector until the bar graph says "ALC".  Set RF
PWR knob to full power.

With the radio on CW and a 50 ohm dummy load connected, close the key and
adjust the MAIN VFO-A knob until the ALC display is about 75-85% of full
scale on the illuminated bar marked "ALC".

Press the next band button (3.5), make sure the radio is still  on CW, and
turn the SUB VFO-B knob clockwise one band to "t iF - 035".

Again adjust MAIN VFO-A until ALC is at 75-85% of full scale.

Repeat this process through all bands.

Most radios I have tested require a setting of 2 to 4 on TX IF gain, with 3
being the most common setting.

This change will reduce SSB bandwidth and distortion. It will also reduce
keyclicks and annoying thumps on the leading edge of each Morse character.

 Hope this helps;

Bill W2PKY





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Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Ed Stokes]

A few more notes about this subject…



1.  The power spike problem can be “avoided” through keeping the xmtr power low 
at the beginning of each cycle and then  gradually increasing it.  I have bit 
of auxiliary code in Xojo which can do this, ramping power up during the first 
5 seconds of the cycle.  

Would anyone care to comment on how this variable power would affect the FT8 
throughput?



2.  I would like to know more about how WSJT-X uses the serial port. 

By experimenting I found that Xojo can “grab” the serial port, interact briefly 
with the radio, then drop the serial line and WSJT-X (with rare exceptions) 
never notices.  

For example, my auxiliary app can open the same serial port which WSJT-X is 
using to control the radio, send some commands to the radio, stay connected for 
100 ms. or so, then close that connection.  WSJT-X seems none the wiser as long 
as the interruption is brief.

When does WSJT-X access the serial port and when is it possible for another app 
to use it without causing a conflict?

73, Ed
W1KOK 

> On Apr 12, 2019, at 2:36 PM, Ed Stokes  wrote:
> 
> Hi Bill,
> 
> Another extremely helpful comment.
> 
> As you may have noted in my previous post, I am not co-located with the 
> equipment.
> 
> Is it possible to access this menu via the serial interface?
> 
> Otherwise, I will have to wait until next month when I am at home again and 
> have physical access to the radio.
> 
> Thanks.
> 
> 73, Ed
> W1KOK 
> 
> 
>> >From W8JI.com , maybe 5000 has similar adjustments. If 
>> >the IF Transmit Gain
>> was too high the 1000 would exhibit huge power spikes on key down or
>> pressing the mike PTT button.
>> 
>> Transmit Gain Menus
>> 
>> The FT-1000 MK V  has hidden transmit gain menus. They are accessed by
>> pushing and holding FAST and LOCK while turning the POWER switch on. Both
>> of my MK V's  and every MK V serviced here has had the TX IF gain set too
>> high. This causes first character clicks on CW and spits and splatter on
>> SSB.  Here is how to correct the IF gain to prevent ALC clipping on leading
>> edges of CW and voice:
>> 
>> Press and hold FAST and LOCK before and during initial POWER on.
>> 
>> Press FAST and ENT at the same time. You are now in the MENU's and the
>> display should say "0-1 GrPI-cH".
>> 
>> Turn the VRF/MEM CH counter-clockwise to 9-2. The display should say "t iF
>> - GA in" This is the transmit IF gain menu.
>> 
>> Turn the SUB VFO knob clockwise one position to  " t iF - 018". This is the
>> 1.8MHz transmit IF gain.
>> 
>> Press the ALC/COMP meter selector until the bar graph says "ALC".  Set RF
>> PWR knob to full power.
>> 
>> With the radio on CW and a 50 ohm dummy load connected, close the key and
>> adjust the MAIN VFO-A knob until the ALC display is about 75-85% of full
>> scale on the illuminated bar marked "ALC".
>> 
>> Press the next band button (3.5), make sure the radio is still  on CW, and
>> turn the SUB VFO-B knob clockwise one band to "t iF - 035".
>> 
>> Again adjust MAIN VFO-A until ALC is at 75-85% of full scale.
>> 
>> Repeat this process through all bands.
>> 
>> Most radios I have tested require a setting of 2 to 4 on TX IF gain, with 3
>> being the most common setting.
>> 
>> This change will reduce SSB bandwidth and distortion. It will also reduce
>> keyclicks and annoying thumps on the leading edge of each Morse character.
>> 
>>  Hope this helps;
>> 
>> Bill W2PKY
>> 
> 

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Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Paul Randall]

Hi James, point taken, my comments were really aimed at traditional alc systems 
that are so prone to producing power spikes.

I have noticed many comments on this thread from people looking for software 
solutions to what look at first sight to be RFI issues. I'm not sure if it has 
been said before but a very simple test that could be recommended to anyone 
whose station is failing or performing strangely is to operate it into a dummy 
load. If the observed problem goes away this removes doubts about the software 
and the fickle finger would point directly at RFI as the culprit. Knowing this 
enables the sufferer to quickly get on the right road towards a solution.

Cheers Paul G3NJV

Sent from my Samsung Galaxy smartphone.


 Original message 
From: James Shaver 
Date: 12/04/2019 19:19 (GMT+00:00)
To: WSJT software development 
Subject: Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each 
transmission?

Hi Paul,

Good info (and similar to my own line of thinking in the response I just sent 
on ALC Overshoot) but I’d recommend one minor change:

Your statement “The best way to avoid spikes in any rig using FT8...” - I’d be 
cautious with the “any rig” generalization.  Some of the popular radios on the 
market with a closed loop power system like the Elecraft K-line and KX-line 
will actually “power hunt” if the ALC meter is not showing 3-4 bars of activity 
on the ALC meter.  The first 4 bars of the ALC meter on the K/KX-line radios 
function like a vu meter and not necessarily indicate ALC action.  The radio 
itself may actually overmodulate the signal in order to get the power output 
set by the power output control and cause a transmitted signal to be quite 
poor.  I was able to test this using my K3 and KX3 into a dummy load and 
viewing the signal output with a spectrum analyzer and the term for the signal 
produced with “0” bars of “ALC” showing was “icky” at best (very technical, I 
know :) ).

Just a word of caution for anyone following this thread.

73,

Jim S.
N2ADV

On Apr 12, 2019, at 2:06 PM, Paul Randall 
mailto:paulfrand...@hotmail.com>> wrote:

Start-of- transmission power spikes will almost certainly occur on any radio 
which is using traditional alc to control output power. Spike severity is 
directly linked to the amount of gain reduction the alc is giving. For example, 
 a 100w rig with power output reduced to 5w using a power control which 
operates via the alc system can be almost relied upon to produce 100w spikes at 
start of transmission. No brainer.

The best way to avoid spikes in any rig using FT8 is to carefully adjust audio 
drive level in the software until desired power output is obtained without the 
rig applying any alc at all. In this way overall system gain is only sufficient 
to produce desired power and no more - so spikes are eliminated and you get a 
cleaner transmission.

That said, I say again that I can exactly  reproduce this problem at will on 
160m where my antenna system clearly puts large voltage onto the cable between 
the pc and the rig. My interface uses industrial quality logic isolators for 
civ and ptt together with audio isolation transformers and dozens of ferrite 
rings on tuner - rig - pc cables.  RFI still gets through and kills the usb 
connection on 160m.  To cure this I will rethink the 160m antenna which I 
suspect is the easiest way.

Regards Paul G3NJV

Sent from my Samsung Galaxy smartphone.


 Original message 
From: Bill Barrett mailto:w2pky...@gmail.com>>
Date: 12/04/2019 18:11 (GMT+00:00)
To: fr...@fkirschner.net<mailto:fr...@fkirschner.net>, WSJT software 
development 
mailto:wsjt-devel@lists.sourceforge.net>>
Subject: Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each 
transmission?

>From W8JI.com<http://W8JI.com>, maybe 5000 has similar adjustments. If the IF 
>Transmit Gain was too high the 1000 would exhibit huge power spikes on key 
>down or pressing the mike PTT button.

Transmit Gain Menus

The FT-1000 MK V  has hidden transmit gain menus. They are accessed by pushing 
and holding FAST and LOCK while turning the POWER switch on. Both of my MK V's  
and every MK V serviced here has had the TX IF gain set too high. This causes 
first character clicks on CW and spits and splatter on SSB.  Here is how to 
correct the IF gain to prevent ALC clipping on leading edges of CW and voice:

Press and hold FAST and LOCK before and during initial POWER on.

Press FAST and ENT at the same time. You are now in the MENU's and the display 
should say "0-1 GrPI-cH".

Turn the VRF/MEM CH counter-clockwise to 9-2. The display should say "t iF - GA 
in" This is the transmit IF gain menu.

Turn the SUB VFO knob clockwise one position to  " t iF - 018". This is the 
1.8MHz transmit IF gain.

Press the ALC/COMP meter selector until the bar graph says "ALC".  Set RF PWR 
knob to full power.

Wi

[wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Ed Stokes]

Hi Paul,

Thanks to you, too.  Your comment on160m confirms my suspicions.  

’m going to take a careful look at the ALC and see if I’ve got that right.

Does anyone know how to entirely disable ALC on a FT5K?  Or, is this just a 
dumb idea?

73, Ed
W1KOK   

I am surprised and pleased that this question has generated so much response.  

I’ve been puzzled by this all winter as I struggled with running 5 to 10 watts 
on Top Band.  

That said, it’s amazing what can be done, including numerous EU, AF, SA and 
VK/ZL contacts, with so little power on 160m!




> Start-of- transmission power spikes will almost certainly occur on any radio 
> which is using traditional alc to control output power. Spike severity is 
> directly linked to the amount of gain reduction the alc is giving. For 
> example,  a 100w rig with power output reduced to 5w using a power control 
> which operates via the alc system can be almost relied upon to produce 100w 
> spikes at start of transmission. No brainer.
> 
> The best way to avoid spikes in any rig using FT8 is to carefully adjust 
> audio drive level in the software until desired power output is obtained 
> without the rig applying any alc at all. In this way overall system gain is 
> only sufficient to produce desired power and no more - so spikes are 
> eliminated and you get a cleaner transmission.
> 
> That said, I say again that I can exactly  reproduce this problem at will on 
> 160m where my antenna system clearly puts large voltage onto the cable 
> between the pc and the rig. My interface uses industrial quality logic 
> isolators for civ and ptt together with audio isolation transformers and 
> dozens of ferrite rings on tuner - rig - pc cables.  RFI still gets through 
> and kills the usb connection on 160m.  To cure this I will rethink the 160m 
> antenna which I suspect is the easiest way.
> 
> Regards Paul G3NJV
> 

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Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Bill Barrett]

Hello Ed-

I am only familiar with adjusting those values through the front panel.
My FT1000 is long gone.
GL

Bill
W2PKY

On Fri, Apr 12, 2019 at 2:36 PM Ed Stokes  wrote:

> Hi Bill,
>
> Another extremely helpful comment.
>
> As you may have noted in my previous post, I am not co-located with the
> equipment.
>
> Is it possible to access this menu via the serial interface?
>
> Otherwise, I will have to wait until next month when I am at home again
> and have physical access to the radio.
>
> Thanks.
>
> 73, Ed
> W1KOK
>
>
> >From W8JI.com, maybe 5000 has similar adjustments. If the IF Transmit Gain
> was too high the 1000 would exhibit huge power spikes on key down or
> pressing the mike PTT button.
>
> Transmit Gain Menus
>
> The FT-1000 MK V  has hidden transmit gain menus. They are accessed by
> pushing and holding FAST and LOCK while turning the POWER switch on. Both
> of my MK V's  and every MK V serviced here has had the TX IF gain set too
> high. This causes first character clicks on CW and spits and splatter on
> SSB.  Here is how to correct the IF gain to prevent ALC clipping on leading
> edges of CW and voice:
>
> Press and hold FAST and LOCK before and during initial POWER on.
>
> Press FAST and ENT at the same time. You are now in the MENU's and the
> display should say "0-1 GrPI-cH".
>
> Turn the VRF/MEM CH counter-clockwise to 9-2. The display should say "t iF
> - GA in" This is the transmit IF gain menu.
>
> Turn the SUB VFO knob clockwise one position to  " t iF - 018". This is the
> 1.8MHz transmit IF gain.
>
> Press the ALC/COMP meter selector until the bar graph says "ALC".  Set RF
> PWR knob to full power.
>
> With the radio on CW and a 50 ohm dummy load connected, close the key and
> adjust the MAIN VFO-A knob until the ALC display is about 75-85% of full
> scale on the illuminated bar marked "ALC".
>
> Press the next band button (3.5), make sure the radio is still  on CW, and
> turn the SUB VFO-B knob clockwise one band to "t iF - 035".
>
> Again adjust MAIN VFO-A until ALC is at 75-85% of full scale.
>
> Repeat this process through all bands.
>
> Most radios I have tested require a setting of 2 to 4 on TX IF gain, with 3
> being the most common setting.
>
> This change will reduce SSB bandwidth and distortion. It will also reduce
> keyclicks and annoying thumps on the leading edge of each Morse character.
>
>  Hope this helps;
>
> Bill W2PKY
>
>
>
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[wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Ed Stokes]

Hi Bill,

Another extremely helpful comment.

As you may have noted in my previous post, I am not co-located with the 
equipment.

Is it possible to access this menu via the serial interface?

Otherwise, I will have to wait until next month when I am at home again and 
have physical access to the radio.

Thanks.

73, Ed
W1KOK   


> >From W8JI.com, maybe 5000 has similar adjustments. If the IF Transmit Gain
> was too high the 1000 would exhibit huge power spikes on key down or
> pressing the mike PTT button.
> 
> Transmit Gain Menus
> 
> The FT-1000 MK V  has hidden transmit gain menus. They are accessed by
> pushing and holding FAST and LOCK while turning the POWER switch on. Both
> of my MK V's  and every MK V serviced here has had the TX IF gain set too
> high. This causes first character clicks on CW and spits and splatter on
> SSB.  Here is how to correct the IF gain to prevent ALC clipping on leading
> edges of CW and voice:
> 
> Press and hold FAST and LOCK before and during initial POWER on.
> 
> Press FAST and ENT at the same time. You are now in the MENU's and the
> display should say "0-1 GrPI-cH".
> 
> Turn the VRF/MEM CH counter-clockwise to 9-2. The display should say "t iF
> - GA in" This is the transmit IF gain menu.
> 
> Turn the SUB VFO knob clockwise one position to  " t iF - 018". This is the
> 1.8MHz transmit IF gain.
> 
> Press the ALC/COMP meter selector until the bar graph says "ALC".  Set RF
> PWR knob to full power.
> 
> With the radio on CW and a 50 ohm dummy load connected, close the key and
> adjust the MAIN VFO-A knob until the ALC display is about 75-85% of full
> scale on the illuminated bar marked "ALC".
> 
> Press the next band button (3.5), make sure the radio is still  on CW, and
> turn the SUB VFO-B knob clockwise one band to "t iF - 035".
> 
> Again adjust MAIN VFO-A until ALC is at 75-85% of full scale.
> 
> Repeat this process through all bands.
> 
> Most radios I have tested require a setting of 2 to 4 on TX IF gain, with 3
> being the most common setting.
> 
> This change will reduce SSB bandwidth and distortion. It will also reduce
> keyclicks and annoying thumps on the leading edge of each Morse character.
> 
>  Hope this helps;
> 
> Bill W2PKY
> 

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[wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Ed Stokes]

John,

Many, many thanks for this helpful idea.  I am not conversant with Hamlib, so 
this will take some study on my part.

73, Ed 
W1KOK


> On Apr 12, 2019, at 10:36 AM, John Nelson via wsjt-devel 
>  wrote:
> 
> Ed,
> 
> I use "Hamlib NET Rigctl” as rig on my station. (I use a Kenwood TS-870s.)
> And then run rigctld-wsjtx in the  background to do the rig control from my 
> Mac.  This way I can also control the rig’s RF Power Level from another 
> computer.   I think this is what you want to do with the routine you want to 
> write.
> 
> — John G4KLA___
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Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[James Shaver]

Hi Paul,

Good info (and similar to my own line of thinking in the response I just sent 
on ALC Overshoot) but I’d recommend one minor change: 

Your statement “The best way to avoid spikes in any rig using FT8...” - I’d be 
cautious with the “any rig” generalization.  Some of the popular radios on the 
market with a closed loop power system like the Elecraft K-line and KX-line 
will actually “power hunt” if the ALC meter is not showing 3-4 bars of activity 
on the ALC meter.  The first 4 bars of the ALC meter on the K/KX-line radios 
function like a vu meter and not necessarily indicate ALC action.  The radio 
itself may actually overmodulate the signal in order to get the power output 
set by the power output control and cause a transmitted signal to be quite 
poor.  I was able to test this using my K3 and KX3 into a dummy load and 
viewing the signal output with a spectrum analyzer and the term for the signal 
produced with “0” bars of “ALC” showing was “icky” at best (very technical, I 
know :) ).  

Just a word of caution for anyone following this thread.  

73,

Jim S. 
N2ADV 

> On Apr 12, 2019, at 2:06 PM, Paul Randall  wrote:
> 
> Start-of- transmission power spikes will almost certainly occur on any radio 
> which is using traditional alc to control output power. Spike severity is 
> directly linked to the amount of gain reduction the alc is giving. For 
> example,  a 100w rig with power output reduced to 5w using a power control 
> which operates via the alc system can be almost relied upon to produce 100w 
> spikes at start of transmission. No brainer. 
> 
> The best way to avoid spikes in any rig using FT8 is to carefully adjust 
> audio drive level in the software until desired power output is obtained 
> without the rig applying any alc at all. In this way overall system gain is 
> only sufficient to produce desired power and no more - so spikes are 
> eliminated and you get a cleaner transmission.
> 
> That said, I say again that I can exactly  reproduce this problem at will on 
> 160m where my antenna system clearly puts large voltage onto the cable 
> between the pc and the rig. My interface uses industrial quality logic 
> isolators for civ and ptt together with audio isolation transformers and 
> dozens of ferrite rings on tuner - rig - pc cables.  RFI still gets through 
> and kills the usb connection on 160m.  To cure this I will rethink the 160m 
> antenna which I suspect is the easiest way. 
> 
> Regards Paul G3NJV
> 
> Sent from my Samsung Galaxy smartphone.
> 
> 
>  Original message 
> From: Bill Barrett 
> Date: 12/04/2019 18:11 (GMT+00:00)
> To: fr...@fkirschner.net, WSJT software development 
> 
> Subject: Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each 
> transmission?
> 
> From W8JI.com, maybe 5000 has similar adjustments. If the IF Transmit Gain 
> was too high the 1000 would exhibit huge power spikes on key down or pressing 
> the mike PTT button.
> 
> Transmit Gain Menus
> 
> The FT-1000 MK V  has hidden transmit gain menus. They are accessed by 
> pushing and holding FAST and LOCK while turning the POWER switch on. Both of 
> my MK V's  and every MK V serviced here has had the TX IF gain set too high. 
> This causes first character clicks on CW and spits and splatter on SSB.  Here 
> is how to correct the IF gain to prevent ALC clipping on leading edges of CW 
> and voice:
> 
> Press and hold FAST and LOCK before and during initial POWER on.
> 
> Press FAST and ENT at the same time. You are now in the MENU's and the 
> display should say "0-1 GrPI-cH".
> 
> Turn the VRF/MEM CH counter-clockwise to 9-2. The display should say "t iF - 
> GA in" This is the transmit IF gain menu.
> 
> Turn the SUB VFO knob clockwise one position to  " t iF - 018". This is the 
> 1.8MHz transmit IF gain.
> 
> Press the ALC/COMP meter selector until the bar graph says "ALC".  Set RF PWR 
> knob to full power.
> 
> With the radio on CW and a 50 ohm dummy load connected, close the key and 
> adjust the MAIN VFO-A knob until the ALC display is about 75-85% of full 
> scale on the illuminated bar marked "ALC".
> 
> Press the next band button (3.5), make sure the radio is still  on CW, and 
> turn the SUB VFO-B knob clockwise one band to "t iF - 035".
> 
> Again adjust MAIN VFO-A until ALC is at 75-85% of full scale.
> 
> Repeat this process through all bands.
> 
> Most radios I have tested require a setting of 2 to 4 on TX IF gain, with 3 
> being the most common setting.
> 
> This change will reduce SSB bandwidth and distortion. It will also reduce 
> keyclicks and annoying thumps on the leading edge of each Morse character.
> 
>  Hope this he

Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[James Shaver]

This almost sounds partially like ALC Overshoot that is more of a problem with 
some radios than with others (it was really nasty on a TS590 that a friend had 
sent to me to test out). The pure 8-tone FSK signal does seem to make this more 
obvious on some of my radios than others.  Some of my radios have a delay 
function that will curb this a bit.  Not sure about the FTDX5000 or about how 
easily those functions would be accessed remotely but it may be worth a look. 

Jim S. 
N2ADV

> On Apr 12, 2019, at 12:38 PM, Frank Kirschner  
> wrote:
> 
> Some rigs, even high-end rigs including the FTdx5000, exhibit a spike on 
> initial transmit. I noticed it mostly with the amp. The power would surge 
> briefly, and then return to the dial value.
> 
> I suspect the combination of the surge and a bit of RFI is causing the 
> problem. I suggest an opto-isolator on both ends of your CAT cable. They are 
> available for RS-232 and USB. That, plus some ferrites along the run should 
> help with the problem. Also, if you're using a desktop, try running several 
> ground straps to the case of the computer. Consumer-grade computers aren't 
> very resistant to RFI, and there is no bonding between the pieces of sheet 
> metal.
> 
> 73,
> Frank
> KF6E
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Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Paul Randall]

Start-of- transmission power spikes will almost certainly occur on any radio 
which is using traditional alc to control output power. Spike severity is 
directly linked to the amount of gain reduction the alc is giving. For example, 
 a 100w rig with power output reduced to 5w using a power control which 
operates via the alc system can be almost relied upon to produce 100w spikes at 
start of transmission. No brainer.

The best way to avoid spikes in any rig using FT8 is to carefully adjust audio 
drive level in the software until desired power output is obtained without the 
rig applying any alc at all. In this way overall system gain is only sufficient 
to produce desired power and no more - so spikes are eliminated and you get a 
cleaner transmission.

That said, I say again that I can exactly  reproduce this problem at will on 
160m where my antenna system clearly puts large voltage onto the cable between 
the pc and the rig. My interface uses industrial quality logic isolators for 
civ and ptt together with audio isolation transformers and dozens of ferrite 
rings on tuner - rig - pc cables.  RFI still gets through and kills the usb 
connection on 160m.  To cure this I will rethink the 160m antenna which I 
suspect is the easiest way.

Regards Paul G3NJV

Sent from my Samsung Galaxy smartphone.


 Original message 
From: Bill Barrett 
Date: 12/04/2019 18:11 (GMT+00:00)
To: fr...@fkirschner.net, WSJT software development 

Subject: Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each 
transmission?

>From W8JI.com, maybe 5000 has similar adjustments. If the IF Transmit Gain was 
>too high the 1000 would exhibit huge power spikes on key down or pressing the 
>mike PTT button.

Transmit Gain Menus

The FT-1000 MK V  has hidden transmit gain menus. They are accessed by pushing 
and holding FAST and LOCK while turning the POWER switch on. Both of my MK V's  
and every MK V serviced here has had the TX IF gain set too high. This causes 
first character clicks on CW and spits and splatter on SSB.  Here is how to 
correct the IF gain to prevent ALC clipping on leading edges of CW and voice:

Press and hold FAST and LOCK before and during initial POWER on.

Press FAST and ENT at the same time. You are now in the MENU's and the display 
should say "0-1 GrPI-cH".

Turn the VRF/MEM CH counter-clockwise to 9-2. The display should say "t iF - GA 
in" This is the transmit IF gain menu.

Turn the SUB VFO knob clockwise one position to  " t iF - 018". This is the 
1.8MHz transmit IF gain.

Press the ALC/COMP meter selector until the bar graph says "ALC".  Set RF PWR 
knob to full power.

With the radio on CW and a 50 ohm dummy load connected, close the key and 
adjust the MAIN VFO-A knob until the ALC display is about 75-85% of full scale 
on the illuminated bar marked "ALC".

Press the next band button (3.5), make sure the radio is still  on CW, and turn 
the SUB VFO-B knob clockwise one band to "t iF - 035".

Again adjust MAIN VFO-A until ALC is at 75-85% of full scale.

Repeat this process through all bands.

Most radios I have tested require a setting of 2 to 4 on TX IF gain, with 3 
being the most common setting.

This change will reduce SSB bandwidth and distortion. It will also reduce 
keyclicks and annoying thumps on the leading edge of each Morse character.

 Hope this helps;

Bill W2PKY

On Fri, Apr 12, 2019 at 12:38 PM Frank Kirschner 
mailto:frank.kirsch...@gmail.com>> wrote:
Some rigs, even high-end rigs including the FTdx5000, exhibit a spike on 
initial transmit. I noticed it mostly with the amp. The power would surge 
briefly, and then return to the dial value.

I suspect the combination of the surge and a bit of RFI is causing the problem. 
I suggest an opto-isolator on both ends of your CAT cable. They are available 
for RS-232 and USB. That, plus some ferrites along the run should help with the 
problem. Also, if you're using a desktop, try running several ground straps to 
the case of the computer. Consumer-grade computers aren't very resistant to 
RFI, and there is no bonding between the pieces of sheet metal.

73,
Frank
KF6E
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Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[John Nelson via wsjt-devel]

Ed,

I use "Hamlib NET Rigctl” as rig on my station. (I use a Kenwood TS-870s.)
And then run rigctld-wsjtx in the  background to do the rig control from my 
Mac.  This way I can also control the rig’s RF Power Level from another 
computer.   I think this is what you want to do with the routine you want to 
write.

— John G4KLA

smime.p7s
Description: S/MIME cryptographic signature
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Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Bill Barrett]

>From W8JI.com, maybe 5000 has similar adjustments. If the IF Transmit Gain
was too high the 1000 would exhibit huge power spikes on key down or
pressing the mike PTT button.

Transmit Gain Menus

The FT-1000 MK V  has hidden transmit gain menus. They are accessed by
pushing and holding FAST and LOCK while turning the POWER switch on. Both
of my MK V's  and every MK V serviced here has had the TX IF gain set too
high. This causes first character clicks on CW and spits and splatter on
SSB.  Here is how to correct the IF gain to prevent ALC clipping on leading
edges of CW and voice:

Press and hold FAST and LOCK before and during initial POWER on.

Press FAST and ENT at the same time. You are now in the MENU's and the
display should say "0-1 GrPI-cH".

Turn the VRF/MEM CH counter-clockwise to 9-2. The display should say "t iF
- GA in" This is the transmit IF gain menu.

Turn the SUB VFO knob clockwise one position to  " t iF - 018". This is the
1.8MHz transmit IF gain.

Press the ALC/COMP meter selector until the bar graph says "ALC".  Set RF
PWR knob to full power.

With the radio on CW and a 50 ohm dummy load connected, close the key and
adjust the MAIN VFO-A knob until the ALC display is about 75-85% of full
scale on the illuminated bar marked "ALC".

Press the next band button (3.5), make sure the radio is still  on CW, and
turn the SUB VFO-B knob clockwise one band to "t iF - 035".

Again adjust MAIN VFO-A until ALC is at 75-85% of full scale.

Repeat this process through all bands.

Most radios I have tested require a setting of 2 to 4 on TX IF gain, with 3
being the most common setting.

This change will reduce SSB bandwidth and distortion. It will also reduce
keyclicks and annoying thumps on the leading edge of each Morse character.

 Hope this helps;

Bill W2PKY

On Fri, Apr 12, 2019 at 12:38 PM Frank Kirschner 
wrote:

> Some rigs, even high-end rigs including the FTdx5000, exhibit a spike on
> initial transmit. I noticed it mostly with the amp. The power would surge
> briefly, and then return to the dial value.
>
> I suspect the combination of the surge and a bit of RFI is causing the
> problem. I suggest an opto-isolator on both ends of your CAT cable. They
> are available for RS-232 and USB. That, plus some ferrites along the run
> should help with the problem. Also, if you're using a desktop, try running
> several ground straps to the case of the computer. Consumer-grade computers
> aren't very resistant to RFI, and there is no bonding between the pieces of
> sheet metal.
>
> 73,
> Frank
> KF6E
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[wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Ed Stokes]

Hi Frank,

Many thanks for your input.

For you and for others who may read this thread, here is some additional 
information.

I think there are several problems working together here.  As you said, I think 
the FTdx-5000 is doing something nasty.  Even when I limit the power setting of 
the rig I can see that it is peaking way above what I set for maximum power on 
the initial spike.

I also agree with you that RFI must be part of the problem because the effect 
is much more noticeable on the low bands and with the 160m dipole.  I can run 
full power on 17m with another dipole cut for that band which is even closer to 
the equipment without any problem.

I am in my winter home in California at the moment and the station in question 
is being run remotely in Vermont, so until I return home n a month no changes 
to the setup are possible.  I have about as much ferrite protection installed 
as can be done (learned from years of experience, HI).  I need to think about 
the opto-isolators…thanks for that idea.  The Mac Mini doesn’t seem capable of 
being grounded although I have given some thought over the years to trying to 
put it inside some kind of Faraday cage.

While it is extremely tedious, I can overcome the problem manually by watching 
until transmission starts at a low power setting (e.g. -42 dB) on wsjt and then 
advancing the power slider (to more like -15 dB).  Generally this works but 
sometimes the audio will still crash, even using this technique.  But, alas, as 
I said…extremely tedious!

It would be so nice if I could just grab the CAT line from wsjt.  I could write 
a little routine to wait a few seconds after the start of transmission and then 
increase the power with my own CAT connection, then drop it back down and give 
the CAT line back to wsjt.  But I suspect that is impossible.

73, Ed
W1KOK   


> Some rigs, even high-end rigs including the FTdx5000, exhibit a spike on
> initial transmit. I noticed it mostly with the amp. The power would surge
> briefly, and then return to the dial value.
> 
> I suspect the combination of the surge and a bit of RFI is causing the
> problem. I suggest an opto-isolator on both ends of your CAT cable. They
> are available for RS-232 and USB. That, plus some ferrites along the run
> should help with the problem. Also, if you're using a desktop, try running
> several ground straps to the case of the computer. Consumer-grade computers
> aren't very resistant to RFI, and there is no bonding between the pieces of
> sheet metal.
> 
> 73,
> Frank
> KF6E

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Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Frank Kirschner]

Some rigs, even high-end rigs including the FTdx5000, exhibit a spike on
initial transmit. I noticed it mostly with the amp. The power would surge
briefly, and then return to the dial value.

I suspect the combination of the surge and a bit of RFI is causing the
problem. I suggest an opto-isolator on both ends of your CAT cable. They
are available for RS-232 and USB. That, plus some ferrites along the run
should help with the problem. Also, if you're using a desktop, try running
several ground straps to the case of the computer. Consumer-grade computers
aren't very resistant to RFI, and there is no bonding between the pieces of
sheet metal.

73,
Frank
KF6E
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[wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Ed Stokes]

Hi Bill

Many thanks once again for your very generous reply to my query.

I am running an FTdx-5000 barefoot into a full size 160m dipole and using CAT 
control.  The speech processor is turned off.  Audio is being fed via the front 
panel mic jack from a Mac Mini.  The A3J TX passband is set at 400-2600 Hz.  
VOX is turned off.

After quite a bit of fiddling this morning with mic gain, bandwidth, power 
settings and other controls I am unable to keep it from crashing the audio at 
the start of each transmission, as described in my previous post.  

If I turn the power setting on wsjtx very low then wait until the transmission 
begins I can then increase the power without crashing the audio.  I can advance 
the power to the fully capability of the FT5k, i.e. 200w.

Is it possible to disable / enable the CAT connection to wsjtx via UTP?  

If I could do that, I could use some software grab the CAT line then command 
the rig to increase the power after wsjtx initiates the transmission cycle and 
then return CAT control to wsjtx at the end of the transmission cycle.

If you have any further ideas, I would love to hear them.

Many thanks 

73, Ed
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Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Bill Somerville]

On 12/04/2019 07:05, Ed Stokes wrote:

I’m curious about something I observe about the FT8 signal modulation.

It appears to produce a pronounced spike in the audio at the beginning of each 
15 second transmission.

When I operate on 160, 80 and 40 meters especially this spike will cause the 
program to stop producing audio.  My computer, a mac mini, is relatively close 
to the 160m dipole being used on these bands, about 50 feet.

If I throttle back to -41 dB or so I can make the transmission begin without 
stopping the audio, although the spike is still evident.

If I then gradually increase the “Pwr” slider I can increase the power without 
causing the audio to crash.

If I leave the power increased the audio will crash immediately after the next 
transmission period begins.

Is this a known problem?

73, Ed
W1KOK   


Hi Ed,

there is no spike in the audio at the start of a FT8 transmission. The 
fine detail is that the audio synthesis starts at a zero-crossing so 
there should be minimum discontinuity. Having said that there are at 
least two ways that the final transmitted signal may not be a faithful 
representation of the audio feed to the rig. Firstly many users employ 
some sort of VOX switching and unless there is elaborate delaying of 
audio going on the start of the signal will be truncated and our efforts 
to start at a zero-crossing are defeated. Secondly many rigs suffer from 
some sort of ALC overshoot characteristic that causes the output power 
to spike, in some cases significantly, for the first few ms of 
transmissions. I can't suggest any cure for VOX induced problems, other 
than switching to CAT or externally hard switched PTT, but they should 
relatively harmless. For the ALC overshoot problems, you can experiment 
with leaving the rig at full power and use audio attenuation to limit 
the output or vice versa, depending on the nature of the rig's ALC 
circuitry one or the other may help. A word of warning, these spikes 
caused by ALC problems can be hard to detect as they are often shorter 
than a power meter can register so may be far more prevalent than 
realized, and can be a common cause of RFI issues. It is worth noting 
that a typical rig PA designed for 100W o/p from transistors is usually 
capable of ~150W o/p or more without ALC control, and I have seen cases 
where a rig throttled back to run a couple of watts o/p will spike right 
up to 150W at the start of transmission. This is very bad behaviour an 
likely to kill any external PA used to increase o/p beyond 100W. This 
was observed on the Icom IC-706 MkI.


On a side note, the waterfall in WSJT-X slow modes like FT8 is optimized 
for weak-signal detection and does tend to exaggerate any signal 
discontinuities. As a taster, the next feature release of WSJT-X 
includes an option to switch to a filtered waterfall, using a 
bell-shaped curve window function to minimize spectral leakage (like 
narrow filter ringing) rather than the rectangular filter implicit in 
the current implementation, that gives a much more faithful 
representation of incoming signals at the cost of a small amount of 
sensitivity. More interesting changes related to this are also in the works.


73
Bill
G4WJS.



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Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Bramax via wsjt-devel]

Hi,
I haven't any RFI issue but I noted the spike at the beginning of any 
trasmission.
I use an Icom 7610 and on the waterfall I clearly see a kind of spike 
that occupies the complete bandwith of audio channel. In my case 
100-2800 Hz.

I can see it at any TX start.
I use the USB audio connection between my rig and the PC.

73s,

Maurizio I2NOY

Il 12/04/2019 08:52, Paul Randall ha scritto:

Ed

I can reproduce this on my setup where my antenna is not good for 160m - 
causing bad RFI which crashes the USB audio link to the PC. If I start 
transmission on 160m with very low power and ease it up I get almost to 
full power before the link fails.


I’ve seen no evidence of a spike, actually my observation suggests the 
commencement of audio seems to be shaped to avoid one.


My guess is that you have RF feedback problems.

Kind regards

Paul G3NJV

Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for 
Windows 10



*From:* Ed Stokes 
*Sent:* Friday, April 12, 2019 7:05:54 AM
*To:* WSJT software development
*Subject:* [wsjt-devel] Does the FT8 signal spike at the beginning of 
each transmission?

I’m curious about something I observe about the FT8 signal modulation.

It appears to produce a pronounced spike in the audio at the beginning 
of each 15 second transmission.


When I operate on 160, 80 and 40 meters especially this spike will cause 
the program to stop producing audio.  My computer, a mac mini, is 
relatively close to the 160m dipole being used on these bands, about 50 
feet.


If I throttle back to -41 dB or so I can make the transmission begin 
without stopping the audio, although the spike is still evident.


If I then gradually increase the “Pwr” slider I can increase the power 
without causing the audio to crash.


If I leave the power increased the audio will crash immediately after 
the next transmission period begins.


Is this a known problem?

73, Ed
W1KOK

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Re: [wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Paul Randall]

Ed

I can reproduce this on my setup where my antenna is not good for 160m - 
causing bad RFI which crashes the USB audio link to the PC. If I start 
transmission on 160m with very low power and ease it up I get almost to full 
power before the link fails.



I’ve seen no evidence of a spike, actually my observation suggests the 
commencement of audio seems to be shaped to avoid one.



My guess is that you have RF feedback problems.



Kind regards

Paul G3NJV



Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10




From: Ed Stokes 
Sent: Friday, April 12, 2019 7:05:54 AM
To: WSJT software development
Subject: [wsjt-devel] Does the FT8 signal spike at the beginning of each 
transmission?

I’m curious about something I observe about the FT8 signal modulation.

It appears to produce a pronounced spike in the audio at the beginning of each 
15 second transmission.

When I operate on 160, 80 and 40 meters especially this spike will cause the 
program to stop producing audio.  My computer, a mac mini, is relatively close 
to the 160m dipole being used on these bands, about 50 feet.

If I throttle back to -41 dB or so I can make the transmission begin without 
stopping the audio, although the spike is still evident.

If I then gradually increase the “Pwr” slider I can increase the power without 
causing the audio to crash.

If I leave the power increased the audio will crash immediately after the next 
transmission period begins.

Is this a known problem?

73, Ed
W1KOK

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[wsjt-devel] Does the FT8 signal spike at the beginning of each transmission?

[Ed Stokes]

I’m curious about something I observe about the FT8 signal modulation.

It appears to produce a pronounced spike in the audio at the beginning of each 
15 second transmission.

When I operate on 160, 80 and 40 meters especially this spike will cause the 
program to stop producing audio.  My computer, a mac mini, is relatively close 
to the 160m dipole being used on these bands, about 50 feet.

If I throttle back to -41 dB or so I can make the transmission begin without 
stopping the audio, although the spike is still evident.  

If I then gradually increase the “Pwr” slider I can increase the power without 
causing the audio to crash.

If I leave the power increased the audio will crash immediately after the next 
transmission period begins.

Is this a known problem?

73, Ed
W1KOK   

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wsjt-devel@lists.sourceforge.net
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