6500 Delay in FT8

JohnSweeney

I recently bought a used 6500.  I am seeing 0.3 seconds delay on every FT8 signal.  My test setup: Kenwood TS590, Win 7 PC, V1.9 of WSJT-X, Flex6500.  I set the time on the PC and recorded a number of stations using the TS590.  Most stations were right around zero DT.  I then connected the Flex to the same PC (& same antenna) and most signals had DT of 0.3.   I also compared my TS990 on a second PC running WSJT-X.   In every case, the DT (delta in time) with the Flex6500 was 0.3 seconds later, regardless of the actual DT number.   I expected some delay with a Flex, but 300ms seems high.   I did a master reset but it did not change anything.  I notice the same delay when changing something simple - like AF volume on my Maestro.  I want to know if the 300ms delay is typical in Flex or is there something wrong with my radio. 

John - AI4FR

I think it is typical due to the circuitry. Listen to WWV with the Flex and also with another non SDR at the same time and you'll hear that .003 difference very clearly. So how do you set the Flex timing for FT8? I get the PC as close as I can and live with the .003/.004 difference.

Cal N3CAL

I normally see a DT of of about 0.3 on WSJT-X FT8 signals using my Flex 6600.  I have an external GPSDO syncing time to my computer.  WSJT-X will decode stations up to a DT around 2.0 or less so 0.3 has never been a issue.   The GPSDO program I'm using is NMEATime.

Cal/N3CAL

Jim KJ7S

My experience with the 6300 and wsjt-x latest has been .4 DT once I use the network  time sync app to make sure the time on the pc is correct, and it's the same whether I use the Dell laptop or the I7 desktop.

Bill -VA3WTB

Comparing it to a radio that does not have the same software processing if any may show a difference in delay.

Tim - W4TME

Do you have the digital mode filters set for lowest latency?

And for faster T/R times, in Settings --> Radio Setup --> TX tab, disable all the options.

There is going to be some latency, because of the physics involved with signal propagation through a DSP filter, but 0.3s is not a barrier to operating FT8.  I have 134 confirmed grids on 6m in the last 3 weeks.

roger na4rr

I Tim I wish that in your spare time   you would update the "how to setup FT8" instructions.  You must be good at multi-tasking. being customer experience manager and ft8 operator and soon to be Mr. Dudley

roger na4rr

Do people actually "talk" on ft8.  I have decoded it and all I see are call signs.  No wx here is  **** or some other exchange.

JohnSweeney

Tim - thank you for your reply.   I agree 0.3s is not a barrier to FT8, but as a new Flex owner, I was not sure if the delay I was seeing was typical or not.  Based on your reply and the others, i see that is normal and I am happy that my 6500 is OK. 

JohnSweeney

John - thank you for your reply.

JohnSweeney

Bill - thank you for confirming that the 0.3s delay is normal.  It is not causing any problems, I am just new to the Flex world.

JohnSweeney

Jim - thank you for your reply!

JohnSweeney

Cal - thank you for confirming that the 0.3s delay is normal.  It is not causing any problems, I am just new to the Flex world.

Martin AA6E

It's not a talk mode. You exchange locators and sig reports and that's normally all. But it's very sensitive and error free.

Ted VE3TRQ

JT9 is more sensitive, however, FT8 is much faster, so more grids per hour :-) I was sad to see everyone abandon JT65 and JT9.

G8ZPX

Rob sherwood measured 162ms on f6700 where the ic7610 was just 12ms for comparison.

JohnSweeney

This is also excellent information - thank you. 

roger na4rr

Trying to figure out FT8 I came across this and thought it was fun.

http://www.ei5di.com/jt.html

jim

I am running FT8 as I type this.  My DT times are showing -1.1 up to 1.0.  
Most DT are between 0.0 and 0.6..

Tim - W4TME

Make sure you are using an NTP client (not SNTP) like Meinberg to correct the PC clock which is known to drift a lot in short periods of time.

John - AI4FR

I should have also added that I have the 6700 with GPSDO. One would think that with this added, my time would be spot on with WWV. Listening to WWV on a traditional receiver and watching the GPS tab under radio settings where there is a GPS clock, I can see/hear the difference. The 6700 GPS clock is behind by a fraction of a second. If I just use the 6700 with GPSDO to monitor WWV, it is spot on perfect and I would never know it was behind. This "operating in the past" has not affected any FT8 QSO's as far as I can tell with around 6.5k in the log. I do have a concern on phone if one attempts to be the first caller trying to break a pile-up. Others have that fraction of a second plus more on you.

Bill -VA3WTB

We are spiting hairs here, A Flex is a top performer in DX, always has been. That fraction of a second is way faster then human reflexes.

The average reaction time for humans is 0.25 seconds to a visual stimulus, 0.17 for an audio stimulus, and 0.15 seconds for a touch stimulus.

John - AI4FR

No splitting hairs Bill. When that DX stations says "QRZ" others will be keying the mic when SDR users are at the RZ in QRZ. Compare the different technologies side by side and you'll quickly hear the time lag. It's almost a half a second delay.

Bill -VA3WTB

Never,,, really, perhaps if they key up before they are finished. SDR is not a handy cap.

John - AI4FR

I usually show .3 or .4 with the Flex. I use  http://www.qsl.net/dl4yhf/rsNTP/rsNTP.htm everyday to set the time on the PC before entering into the FT8 world. No worries about the time difference as my 756 Pro2 rarely would report a 0.0, Seems all our PC clocks are a little off one way or the other. If you are decoding and getting decoded you are fine, just get out there and have some fun.

On a side note, there are times when a station is way off time wise that is trying to answer you. With the above program you can quickly change your time to make the QSO.

G8ZPX

FT8 is not a "human" mode therefore human reaction has no sway. FT8 is a computer communication protocol needing millisecond accurate timing and fractional RTT responses to make it work well. Key-up and latency of TX data streams need to be as good and as quick as any analogue radio.

Bill -VA3WTB

That being said, Flex does really well on FT8,, interesting!!

G8ZPX

Almost as good as an ft101+sound blaster is not much of an accolade

Roger_W6VZV

I get the .3/.4 a lot with my 6400M.  I do great on FT8 and have busted many pileups.

Bill W2PKY

Ran a test today using a jumper from the speaker jack on the radio to a separate PC and compared the DT time between a PC using Ethernet and DAX compared to a PC driven by the speaker output of the radio. The wired connection was .2 seconds faster than the times on the PC using DAX. Times on the directly wired PC were as low as .1 .. Looks like DAX creates a .2 delay. This on an i7 4790 4 Ghz PC with 16 Gigs of memory.

David Decoons, wo2x

I also see .3 on average for most FT8 signals with a 6600. Never an issue. WSJT-X can work to 2 seconds or more. Use a good time sync such as Meinberg and you’ll be fine.. Dave wo2x