What is wrong with this 6500 FT8 receive signal?

Ernie Barnhart

The strong signal originated 0.7 mile away. I have spoken to the individual a few times. He said he had someone else check his signal and it looked good to them, perhaps my problem was because we were so close. He is using an IC7300 and says he has it adjusted correctly. I would like another opinion. The signal interferes with my receptions.


Thank you.

Tim Blank

Is your noise blanket on?

JohnK2CIB

What I am seeing is your transmit, not his.  The receive periods look fine.  The XMIT light is on.  It is normal to see such artifacts looking at your own transmit.

Charlie, WA3UTC

John, you are not seeing him transmitting.   What you see is the slice he has selected for transmit.

Geoff AB6BT

I agree, WSJT-X is in Monitor mode.

Lawrence Gray

I regularly see bad signals on FT8. They are caused by having the audio too high--just over driving and causing splatter. I have seen it so bad that there were 3 decodes from the same signal.

David Decoons, wo2x

I see your DAX RX level is way too high. WSJT-X should be around 50, not 70. Also he is 40 over. Try partially disconnecting the antenna connector from the back of the radio to attenuate his signal more and see if it clears up.

I had a ham 1.5 miles away complaining of my signal and it was I was just too strong for him. He was seeing something similar to what you show.

You can move to the alternate time slot when he is on so you both are transmitting at the same time. Not a fix but a way to co-exist.

Dave wo2x

David - KO1C

Great advice, Dave!

David KO1C

Ernie Barnhart

NB was at 0, WNB was at 0. He is transmitting now and it makes no significant difference what the settings are.

Ernie Barnhart

He was transmitting. The MOX light is not on - it is when I transmit. WSJT-X "Enable Tx" is not on. I am talking about the multiple FT8 signals and wide signal of the active transmitter. What are you talking about?

Ernie Barnhart

Thank you Dave. My Control Panel says Slice A RX gain is 32. What are you talking about? WSJT-X thermometer is not in the Red. I have received other station 1.7 miles away and there +18 signal looks pretty normal. Thank you for the suggestion.

Ernie, Ndve

Ernie Barnhart

Thank you Lawrence. I have seen 3 decodes from his signal at times. Could my receiver be overdriven at the distance mentioned? That is what he is suggesting.

Ernie Barnhart

David,

My normal WSJT-X Thermometer is 50 and below except when he transmits. He used to go into the red until I added the -10dB attenuation and reduced AGC-T to about 8 with AGC OFF for the graphic I posted. It is not in the red.

Patrick

You begin to see RX artifacts when signal get above 40 + db over S9.  I have a fellow ham that I see such high artifacts.  Attenuating or turning my antenna to my best null condition reduces it.  Off frequency signals up away from this big signal will be OK.  But on the other side of the coin there may be some overdrive, not evident at distant stations as the overdrive may not be noticeable.  The neighbor should tune his drive better and would probably improve the neighbors copyability by distant stations. 

Patrick

Yes, coexistence....

Ernie

Dave wo2x,


I am receiving him on a different band right now (20M). As seen in the graphic I had added a -10 dB attenuation internally to the antenna input. I added another 10 dB externally to the receive antenna, it cleared up his signal some. I am receiving him on two frequencies with different separations depending on his transmit frequency. Is this an indication that he is overdriven?

Thank you.

David Decoons, wo2x

Yes.  I have seen the double decode from stations overdriving their TX audio.

Easy thing he can do for a test is for him to start lowering the power slider on right in WSJT-X until he sees a slight drop in TX power. Then look at his signal at that point to see if it clears up.

When his TX audio level is set correctly he should be seeing power out close to where his radio TX power setting is set. Going higher with audio will not increase power past that point but will cause him to splatter.

There is a setting on the 7300 he may need to adjust to lower the USB audio out level (if he is using the USB interface).

Dave wo2x

Ernie

Thank you. I will try to work with him using all the information today.

Ernie

Ernie

Correction NB was 50 not 0.

N8AUM

I get this problem often while xmitting in WSPR mode. Running 1 or 2 watts and during my xmit cycle it clears up when I toggle the DAX in the DAX panel. I noticed that Ernie's WSJT's waterfall looks normal to my OLD eyes. I usually see that show up there also if someones signal over driven or has problems and get multiple decodes from same call regardless of signal strength.
Here is a screen shot from today after I was in xmitting in WSPR mode:

https://www.dropbox.com/s/j7lugqj0qcvo4ve/Screenshot%202020-03-16%2010.32.20.png?dl=0