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

[Black M. <mdb...@ya...>]

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 <w1...@co...> 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 <w1...@co...> 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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