Latency 1.4.....Improvement?

ctate243

Steve I think the hard core contesters, (a group I belong too) would appreciate a balanced solution to this latency presented.  It WILL make a difference. Optimally a way to do this without much compromise would be key here.  and if there is no way to correct it without sacrifice, then it should be a option that can be invoked with a click... I am sure you wizards can make it happen ;-).  I know what the power contesters are looking for.. and the flex is on the radar scope of many of them.  a few tweaks in this regard could very well put it in the bulls eye.

Paul Christensen, W9AC

As a physics professor of mine once declared:  "One measurement is worth 10,000 words."

I'll have a look at the ARRL test procedures.

Paul, W9AC

George - AB4FH

As a former physics professor, I agree.  "First there is the measurement" Blaise Pascal circa 1640.  BTW, during my working career I often was in the hometown of Blaise Pascal, Clermont-Ferrand.  There is a school and a museum named after him.

Paul, I don't know if you ever talked to Katashi Nose, KH6IJ, but he was a physics teacher as well as a world renowned contester.  Amazing op who could easily copy 75 wpm in his head...very likeable, too.

Steve N4LQ

Mainly what I can't understand is why the huge difference between the Flex5k and 6k latency. 

KY6LA_Howard

Because most of the time when you hold a frequency it is like a DX Pileup so you are trying to separate the callers in your head... Frankly the slightly later callers are usually heard better than the call stompers.

Americans speak at 5-7 syllables per second - so 100ms is perhaps 1/2 a Syllable lost...So if they are saying Kilo Yankee Six Lima Alpha.. the lost sound would be half of Ki syllable.. something one easily correctly integrates back in your head..

Non Native English speakers talk at much slower rates so you likely would not even miss that first 1/2 syllable.

Paul Christensen, W9AC

I just looked at the ARRL's Tx to Rx Turn-Around test procedure (Sec. 4.9) but note that: (1) Fig. 4-9 needs correction to show TRANSCEIVER and not TRANSMITTER.  At first, I could not understand why they wanted to sample audio from the transmitter to determine Rx recovery time; and (2) Fig. 4-9A needs a lot of clarification.  What is the upper trace?  Why is the trace delayed? Where exactly does key-up occur on the display?   I see two envelopes.  Is one RF and the other audio?   If so, which?   Those two figures need cleaning up to make any sense.

Paul, W9AC 

ctate243

Might be worth emailing the test lab.

Steve-N5AC

The latency is reduced for CW, where the judgment was that it mattered more.  This is detailed in the manual.

Ken - NM9P

Howard, I agree with you on phone.  On CW it might be a little bit different.  You might totally miss the first letter of someone's call.

BTW... There are many other factors to reduced rate.  For example, running to FAST on CW requires more repeats because you are sending over the heads of the majority of contesters.  I have seen many articles that recommend speeds between 28-32 WPM, and no more than 35 WPM in a contest, especially if your call or report has lots of "dits" in it, (because they are the ones most prone to copying errors).  I cannot fathom why some people see the need to send at 40, 45 or 50 WPM in a contest.  They have gone well past the point of diminishing returns in the CW exchange game.  

When rag chewing with friends or handling traffic with experienced operators, I can understand the advantage of very high speeds.  But in contest style exchanges with operators of various skill levels, I think excessive speed is counter-productive.  If nothing else, it wastes other people's time as they try to copy your call and decide if you are fair-game or a dupe.  Frankly, I think that is kind of rude.

Ken - NM9P

Stu Phillips - K6TU

Indeed!  I've not had much interaction with them but the little I've had, they are very responsive.  I think Ed W1RFI is the lab supervisor.

Paul - would you be willing to give Ed a call or an email since you have the context and comparable testing?

Stu K6TU

Paul Christensen, W9AC

We should also keep in mind that latency is not the same as turn-around time. Paul, W9AC

ctate243

good point.

Paul Christensen, W9AC

Makes sense. I was wrongly thinking in terms of bandwidth and not shape factor. Paul, W9AC

George - AB4FH

Paul,
In plain talk, I would like to know:
a.  Time from when my RF transmitted stops until the received audio starts - this would be pertinent for contesters while Running Q's
b.  Time from when I press the function key for the CWX macro that feeds N1MM+ until the RF starts  - this is more complicated I understand but would be pertinent for contesters while S&P'ing Q's

Others, please change the wording if you have a better way of expressing what you want.

Thanks in advance for chasing this down and performing the measurements.

Ken - NM9P

Indeed, option 'b.' is more complicated, because it depends upon more things...If I have the focus on the Flex and hit 'F4' to send my call it is faster than when I hit the AUX1 button on my Flex Control Knob, which has more delay before sending.  And when I use a button on the Hercules DJControl LE MIDI controller that I am programming (with Help from William) it seems to be somewhere in between, or closer to the command directly to the Flex.  When running N1MM+  it seems to be a little bit different, but pretty fast.

If I remember Paul's previous tests correctly, the key-up-to-receive-audio time was pretty good on CW.  It has to be, if they could run 100 WPM QSK with separate antennas.

Ken - NM9P

George - AB4FH

Steve, N5AC reminded me that there is a table of latency as a function of mode and bandwidth in the SSDR 1.4 Software Users Guide.  Here is a clip of the table:
This doesn't explain why ARRL measured 138 ms for SSB, though. In contest mode I could live with 43 ms with VG filtering and Med latency <=400 Hz.

KY6LA_Howard

That explains why I found the latency so low when running DIGU and DAX Audio when remoting...

George - AB4FH

Thanks, Steve, I took the liberty of copying and pasting the table in a post below.  What do I need to do to the select the number of taps to achieve 43 ms on CW at <=400Hz?  This is a compromise I can live with in contest mode. Unless, of course,
you can pull some more magic out of the "lab experiment" that you all are conducting for SSDR V1.4.  :-)

KY6LA_Howard

Frankly as a Sometimes Very Serious Contester.. the one major drawback for S&P is the lack of integrated spots into the Flex Display..

Clearly not an issue when running a frequency but a definite limitation on S&P... 

Yes.. I know Writelog has a pretty good bandmap but it is static and does not correlate to the actual received signals on the Flex Display so one does not know if one should waste time listening on the spotted frequency or not..

If working S&P in contests we run NaP3 on a (Heaven Forbid) K3... the integrated spots into the Real Time display make a huge difference to rate as you can see immediately if the spot is actually there to work....

Ken - NM9P

Howard,  I know your CW Key is tied to a brick at the bottom of Davy Jones' Locker....(;p) but...

On my last CW contests, CQ160CW and ARRLDXCW, I used N1MM+ and CW Skimmwe, which gave a wonderful band map of all the stations I could copy, and I could use the QSY technique that others have mentioned with the CTRL <&> buttons.  What a difference it made!  I wasn't limited only to the stations that were spotted by others, but I was able to have on my display and QSY controls the stations that my own receiver was actually hearing.  Next time I will open multiple skimmers on different bands and let them give me a head start for Band changes and multiplier hunting.  I haven't perfected this yet.  I figure that if I add one new tool to the contesting arsenal  each contest or two, then I will be making good progress.

To bad there isn't a Skimmer for voice modes yet!

Stu, et. al. Have you tested RTTY skimmer under the duress of contest situations yet?  
I need to know if it is worth the money....CQ Skimmer sure has been.

Ken - NM9P

Stu Phillips - K6TU

Ken - haven't tried RTTY skimmer yet...
Stu K6TU

George - AB4FH

Howard, while I don't put in the ****-in-chair time to win contests because, frankly, I'm only interested in the exhilaration and intensity for a few hours, using N1MM+, CW Skimmer, SO2V  in S&P mode, I have achieved rates over 100 Q's per hour (peaked 70 Q's for 30 minutes once).  With N1MM+ 's keyboard shortcuts, I rarely look at the band map.  I just tap cntrl + up or down key to jump to the next unworked station.  The logger keeps track of everything else.  If the rig is a little off the station's frequency, I only have to tap control + "<" or ">" to move a user defined step.  Another reason to not use the visual band map is that it gets so crowded.  While you could use the mouse and "point & click", we both know that we need to keep our hands on the keyboard at all times for speed.

BTW, my hat's off to you for your achievements in winning contests.  [Back in the 1970's I was more serious and won SC section on occasions, if people remember WB4PDQ].

Charles - K5UA

One of the posts in this conversation implied a truncation of the first 3.5 elements of his call in CW at 30 wpm if the latency is 140 msec.

My question is this.... are any elements being being truncated?  That would seem to make QSK impossible, and we know that the 6000 series can do QSK at very high speeds.  Or are these elements simply being delayed?  If they are just delayed, that brings up a different question....

 Does the station with the quickest reply (let's say140 msec quicker) receive the prize of a return call from the DX station being pounced upon?  No, I would hazard a guess to say hardly ever in a pileup. So who does get the contact the vast majority of the time?  I'd say the station that is 3 dB (or more) above the pileup.  So unless YOU are that +3dB station above the pileup, you are not not affected by that 140 msec delay. Ever see what happens when the BIG DOG gets to the plate of food 140 msec behind the little dogs?

 In fact... in a pileup.... all stations being equal in strength, it is often the station that tail-ends after the horde makes their unintelligible racket for a second or two that gets the return call.  I have heard this consistently in pileups and contests for the past 56 years. So if you are not the BIG DOG, being 50 msec ahead of the horde is not going to make a difference.

 Since this 140 msec is so significant, shouldn't we also be talking about not eating or not taking bathroom breaks or not sleeping during contests

 I am not saying that reducing the turn around time has no merit, I just think justifying it based upon contest scores is really a stretch.  One would think the QSK ops would be the ones raising the issue of latency.

The trade-off between latency and filter shape factor that is now in SmartSDR has given the 6000 series the best filters in amateur radio.  All who want to give that up, keep complaining about latency.... but be careful, you may get what you ask for.  And you won't like it.

Steve-N5AC

The paddle-down to RF out on the FLEX-6000 is a world-class ~8ms.  So this is not an issue.  It is on the receive side where there is filtering that you have the latency. The latency in CW is also less on receive because we adjust the filter based on the bandwidth of the passband to have a good shape factor, but not "overdo" the filter. 

Stu Phillips - K6TU

I'm still not sure we are all talking about the same thing here...

Latency simply imparts a delay - what I hear happened some time back and as long as the time is small (100 mS is fine) its not an issue.

Turn around time is something else.  

Turn around time is the window of time from when the transmit PTT is raised and I can copy USABLE audio from the receiver.  I believe that is what the ARRL test measures.

The key question is from the point where PTT is raised, what is the DEAD TIME where nothing is copied by the receiver that can be used as usable audio?

If that dead time causes me to have to ask for a fill or a repeat, its not the size of the DEAD TIME that is the issue, its the time it takes for a repeat - that is seconds, not milliseconds.

Yes, I count seconds per QSO because over a full weekend it translates into a significant number of ADDITIONAL QSO's if I can save it.

As an example, I work really hard to only use phonetics when I have to and not endlessly repeat my callsign as KILO SIX TANGO UNIFORM but as K6TU - believe me, it all adds up.  

In the 2014 Cal QSO Party which is 24 operating hours out of a 30 hour contest, I made 1555 QSOs...  if I can avoid a second per Q, that's another 25-35 contacts I can make...

For me, this is significant.
Stu K6TU

PS: so what is the DEAD TIME in milliseconds?  Is it the 184mS ARRL claims?
Second question - why is PowerSDR so much better on the same measurement?

KY6LA_Howard

I think we are confusing SSB vs CW vs RTTY Contesting...

140ms latency is not really a significant issue in SSB Contesting as the human brain can usually integrate the odd time you miss a 1/2 syllable.  Realistically most contesters are not EXPERTS so few S&P operators will jump onto your call within that 140ms latency delay....

I have actually (without knowing that it had less latency) run a few contests via DIGU and DAX.. did seem a tad quicker but not enough that I really felt a difference... I have used DIGU and DAX for Remote - where i did notice a quicker turn around.. but the Internet Latency was the real issue so every bit helped...

I can't comment on CW Contesting.  No experience whatsoever

On RTTY Contesting... I can see where latency could be a major issue.. but then I have never come in the top 10 in an RTTY contest.. so until I build my RTTY Skill levels to contest grade, I doubt that the latency will have that much effect on my scores..


Contesting Comments

This weekend is my favorite contest WPX SSB...  I am usually the only KY6 in the contest so I am a desirable multiplier which means that I can hold a frequency for the entire 48 hour contest and everyone comes to me.  easy to do 100-200 Q/hr for a while anyways....   IIRC I have done over 2K Q's a couple of times   Enough to dominate my area but Not as good as some of the Europeans who rack up 4-5K Q's 

HOWEVER..XYL is NOT traveling this weekend .. so **** in the chair time will likely be severely limited...  Likely only a very few hours of rates 100-200 Q/hr followed by intense silence...

My other favorite contests from my QTH are Asia Pacific and JIDX SSB Contests because my SteppIR MonstIR @85' @600' ASL 1KM from Pacific gives me about 30 minute longer openings at each end than anyone else in NA... Really helps to have a big station...as those contests seem to be like shooting fish in a barrel.. I tend to own the Pacific in contests.. I only wish I could same for Europe where the 1000' mountain in my backyard kills propagation....

BTW... love working the Japanese in contests.. they are so disciplined that I can get the rate up to almost 300 Q/hr by sitting on a frequency... I really wish some of the Europeans would take contest discipline lessons from the Japanese as everyone's rates would be better..

When we work ARRL Contests... I usually head up to the NX6T contest station which has the big gun to the East (I have a 1000' mountain in my backyard to the East)...  NX6T wins lots of contests every year..   Mainly with K3's albeit we have many different transceivers (K3, 6700, KX3, FT 5000, 7800 to name a few)....  

As i said the big difference maker for S&P is to use the NaP3 App to integrate Spots into the real time display on the K3.

By my estimates that can almost double S&P rates from 60Q/hr to over 100Q/Hr...

Why ......because you don't have to waste time trying to listen for spots you cannot see on the display as being workable...  the lack of integrated spots is the one major shortcoming of the 6700 for S&P Contesting...

Finally .. they run a Contest University, every year at the Visalia International DX Convention and at Dayton.. the crowd is much more sophisticated at Visalia...

Mike NN9DD

The change is ms is 111 The is little more than 1/10th of a second. I don't know about you but that's way down the list of things holding me back from working all entities, state, counties. So far down the list that it never crossed my kind and now that I know I hope it never crosses my mind again. The ability to hear thing and **** them out is far more important then 1/10th of a second Mike N9DFD

W7NGA

I don't have much of a dog in this hunt as I believe contesting to be the bane of amateur radio .. but I digress. no dog, but I do have a research-grade electronics lab and took the time to make a few measurements.

latency AM   - 135.5ms
latency SSB - 146.5ms

remember too, that the sending station also has latency and switchover times that may help ameliorate the timing dependencies. geez .. I just want to call CQ and get an answer. any answer .. even if I have to wait an interminable 150ms!

I do have my Flex 6300 outputting a bodacious AM signal that I am very pleased with.

dan  W7NGA
San Juan Island, Wa.

Ross - K9COX

The only relays that I know of that take that much time are usually hand operated with a very long throw.

Stu Phillips - K6TU

And as a follow-up...

Some web searching shows an average speaking rate of around 150 wpm and that's about 240 syllables  per minute or 4 per second.

So if the DEAD TIME is approaching 200 mS... that says I can miss a syllable like in Ki-Lo all I get to hear is the Lo...  Say the guy coming back to the CQ jumps the gun ever so slightly...  all I may here is "o"or perhaps just SIX TANGO UNIFORM.

My response?  TANGO UNIFORM again?  

GOLF is one sylllable so GOLF FIVE MIKE becomes FIVE MIKE...

My response?  FIVE MIKE AGAIN?

THIS is why this matters.

Those of you who have never run at high rate or had to deal with New York Air Traffic Controllers (who speak WAAAAYYYY faster than 150 wpm) are free to doubt.

Having done both...  I would still like the answer to what is the DEAD TIME before finding another morbid equine to flagellate.

Steve N5AC?  Any views???

Stu K6TU