Receive Latency

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I just made some measurements on cw receive latency and wanted to share them.  I used a simple methodology of recording the tx sidetone in my K3S while transmitting a single dit and recording the subsequent cw receive in a Flex 6500, Orion II, and ANAN-100D all set for 400hz receive and no dsp functions engaged.  The latency figures measured  were 175msec, 45msec, and 70msec respectively.  I hope going forward the Flex number can be improved.  175msec is just long enough that it's getting to the point of me being slightly delayed when trying to quickly respond in a dx pileup.

73, Barry N1EU
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Barry N1EU

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Posted 4 years ago

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Sergey, R5AU

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Hi Barry, this is not new and you well confirm what we have on hands for now with F6000 UM:

however such mesurements are verys depends on the filters shape factor you know what was discussed ex. here:  https://community.flexradio.com/flexradio/topics/cw_filter_shape_factors?topic-reply-list%5Bsettings%5D%5Bfilter_by%5D=all

i am not againts with you notes but necessary to have apple-to-apple compare
or we need to talk concerning introduction of the  Shape Factor "tuning knob" into the F6000

P.S. personally i have no issue with Latency, usually my setup is CW 400Hz and 32WPM and higher
(Edited)
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K0UNX

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My Apple Macs give you a choice of analog output or FIBRE output.  So does my TV, and my HI-FI equipment.  I had gone the FIBRE route to eliminate physical connections, ground loops, and the hum associated with connecting things together.  It didn't take long to realize that whenever you have AD and DA converters, you introduce latency with each step.  The result is "LIP-SYNC" problems watching TV and ECHO effect with audio.

SDR's have to take analog signals and digitize them to send them over a network or to process them.  On the other end of the pipe, the computer or terminal (Maestro, etc.) has to convert the digital stream back to analog for our ears.

The TV in our living room was purchased in 1974, and has a "converter box" to receive OTA HDTV and present it on that old set.  We also have a modern HDTV in another room.  The latency between the two when you're standing halfway between them is on the order of FIVE SECONDS.

Yup!  Latency is with us.

I've gone back to analog wires connecting my stuff together, and put away all the fibre gear.

Jim
K0UNX
Littleton, Colorado
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Barry N1EU

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Thanks Sergey, but I'm not seeing 85msec, I'm seeing twice that much latency - big difference that concerns me.
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Sergey, R5AU

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Barry, i assume you mesured two way signal cirucaltion, however in the table mentioned one direction ex. from  the Mic to Ant
(Edited)
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Barry N1EU

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No Sergey, this is 175msec ONE way, from antenna to speakers/headphones.
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Sergey, R5AU

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Got it, very strange, I'll remesure at the next weekend
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Andrew O'Brien

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Just to stir things up... is there any evidence that a 175 Msec delay makes ANY difference in whether the DX station picks you out or not ?  That delay might actually help.
Andy K3UK
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Mark Griffin

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Barry,
This is nothing new. If you were to take a Flex User poll and ask them to pick between lower latency versus unlimited filter width, the unlimited filter width would win out. I myself have a K3 and also a Kenwood TS-990S.

The K3 has hardware filters and so does the Kenwood. And of course you can adjust the width of the filter with the limits of the firmware that is installed. Do you use your Flex for contesting?

The contest radio club I belong to was to have N4HY, who was one of the architects of Flex Radio at our club meeting tonight. But due to illness he is not able to make it. I was going to ask him some questions related to the Flex after the meeting. But that will have to wait for another time as they say.

I was going to purchase a Flex. I was very impressed with the hardware performance. But with all the issues that are software related, I purchased the 990S. I just see too many issues when it comes to software. That is why I was very apprehensive. Mark Griffin, KB3Z
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Barry N1EU

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If you don't do a lot of contesting, this is probably a non-issue.  But I often engage in trying to bust a pileup for a needed multiplier.  Precise timing of my calls is crucial in the ebb and flow of the pileup.  175msec is enough to throw my timing off a bit.  

I'm under the impression that Flex is seriously going after the contester market, so I think this IS an issue.

Maybe the filter slopes need to be slightly shallower but that's not currently a configurable parameter.
(Edited)
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Lewis Cheek

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I have a 6500, and the more I use it in cw while contesting the less I like it. The total delay is not something I like. My hope is after Maestro is rolled out ( I NEED KNOBS ) Flex will work on reducing latency, if not I'll be moving back to Elecraft. Many times the station I'm working is well into the exchange or calling cq before my receiver is switched. I know a couple of BIG time contest stations are using Flex and perhaps their input will help resolve.

Lew
N4CO
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W7NGA

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Lew, could you expound further? I am trying to follow your example. You are transmitting, stop, and after the Flex switches to receive the other station is already mid-CQ? It seems to me that the time to go from transmit to receive is essentially instantaneous (~7ms) and you receive almost immediately. The latency contributes a delay before you hear the signal only. Reversing this line of thought, you are hearing the other stations CQ ~165ms after they stop transmitting. They should hear your reply about ~170ms after they stop and listen (ignoring their own latencies). I measured this at one time but there is essentially zero latency between key-down and RF at the antenna.

W7NGA  dan
(Edited)
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Lewis Cheek

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Dan, guess I need to work on this a bit :). When I stop xmit and start hearing the other station they are well into the exchange before I hear them. Now I do understand some guys are quick, and perhaps they don't wait until I have finished :). However, this occurs very often. I usually run using a 400 hz bandwidth.Wish I had a way to test this myself. I'll really be disappointed if Maestro exacerbates this. For my operating gaining some knob control is all I need. I'm looking to be able to use my left hand with Maestro and keep my right hand on keyboard, etc.

Lew
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W7NGA

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Lewis, I removed my comment about Maestro because I realize now that to be a contesting machine you must be hard-wired to the Flex and not be Remote. If latency is a problem now, you sure don't want to add networking delays.  I was enthused about Maestro to use it as an expensive FlexControl but I have been told that it cannot control SSDR on the PC. Perhaps in the future. I have become far too accustomed to my beautiful 24" displays, and 4 slices, to fall backwards with the Maestro.
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W7NGA

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Let's back up some more. Your signal travels at 186 miles-per-millisecond. About 1300 miles during your T/R switching interval. About 15,000 miles in the difference between a very low latency receiver and the Flex. Hmm .. not much. 

So, the issue would be when the transmitting station finishes calling CQ, you will not be able to know this until ~165ms after the fact (should we include transit times?). You hear him stop, your brain processes this fact and introduces its own latency, and your arm eventually presses the CW key to transmit his call. 

Instead of buying a new radio, wouldn't one be almost better off to simply hone their reflexes? Reflex exercises. See the light, press the buzzer. Or maybe just move closer to the DX station(s) and buy yourself a millisecond? Hehehehe .... 
(Edited)
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Lewis Cheek

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You're on to something here! Just need to also account for rotation of earth and if signal is coming from west to east, east to west, north to south or south to north. My xyl says I don't hear well, so maybe a good wax job prior to contest is in order. :)
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W7NGA

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Well, I *do* understand Barry's concerns. I am just surprised that latency is the problem it appears to be. 
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Walt - KZ1F

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Mark and Barry, you both mention you have multiple radios. Something I've never quite understood is how does that work? For instance, I have 3, the 530 and 1500 are collecting dust. Someone, a yr or two ago, said their k3s was their everyday radio but then when is the 6000 used? So I was curious in your two cases.
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Mark Griffin

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Walt,
I was going to do a SO2R situation when I considered adding the flexradio. I had a Top Ten DX Doubler all ready to go. But after getting my 990S I have a main receiver as well as a sub receiver.

That is one option I did not have with my K3. So when I use my 990S with N1MM Plus for contesting  I have the software set for S02R and I can see a bandmap not only for spots on the main receiver but also the Sub Receiver.

Currently my K3 is sitting on a couch. I have it as a backup rig just in case the 990S falls to pieces. And I hope that doesn't happen! I just used my 990S for the CQWW SSB and CW contests, and I prefer it over my K3.
Just personal preference I guess.

Hopefully this gives you some insight on how I operate when it comes to contests.

With day to day operating I will probably be on 40 meter CW which is what I have the main receiver on. The sub receiver I usually have on 40 meter SSB. I have 2 speakers so I can listen to both.

Mark Griffin, KB3Z
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Walt - KZ1F

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That's great, thank you Mark. A few months back I had to take a road trip to HRO in NH to return a rotor. The gas it took was way less than shipping and I got to see, feel, and play with their radios. Absent were Flex, and Elecraft. But the 990s was there as were Icoms and Yaesu's. I liked the 990, aside from it's size and weight, it seemed pretty full featured. Now that is a candy shop. This is meant as a rhetorical and I am certain FRS has already 'done the math' but I wonder if selling retail would ultimately sell more units with a positive margin for FRS. It's gotta be deemed less profitable for whatever reason. I didn't see Alinco's there either, not that I was looking for them,
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Mark Griffin

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Walt,
You make an excellent point that neither Flex or Elecraft were at HRO. Elecraft is basically either a kit or assembled. And you pick the options that you want. Flexradio is pretty basic except for adding a GPS or Antenna Tuner on the 6300. Both Elecraft and Flexradio seem to be quite successful with their marketing strategy.

My first major radio was a TS-940 and I was going to reactivate that one. But decided to get the 990S instead. Plus the deal that HRO had where it was about 1500 dollars less was a major reason why I purchased it. It is a large, heavy rig, but with all the features I really like it. There is a learning curve, but that will happen with any piece of equipment you buy today.
Mark Griffin, KB3Z
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Andreas Junge, Elmer

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Barry,

are you measuring the delay at the speaker output in the back of the radio or are you using the "Remote" audio? I am sure the latency table from the manual is based on output at the speaker port of the radio.

Routing the audio through the "Remote" seems to add a considerable amount of latency.

73, Andreas, N6NU
(Edited)
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Barry N1EU

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It's measured at the rear panel speaker output.

I suspect that the current 6K steep filter slopes is a double negative for cw contesting - it results in greater latency and it stops you from hearing off-frequency callers when you're running.  Not-too-shallow, not-too-steep is what's needed - like the PowerSDR "1024 buffers" slope that matches the Orion slope:

cwrxbufferjpg
(Edited)
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Sergey, R5AU

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Barry with F6K in use FIR filters what a different from the regular one what you explained, but latency measurement results what you get are very strange 
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Craig K9CT

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Barry

My opinion is that this latency is real but not having any effect on the ability to DX or Contest. I have been grinding away using SO2R and have not seen any negative effect in SSCW or ARRL 160. I can listen to my second harmonic and get a feel for the latency. I don't change my operating at all.

Being on the DXpedition side of things...some delay before calling is a GOOD thing. Almost everyone calls at the same time. The DX station is usually tuning away from the last station worked in a split and it takes a half second before he can hear the next call. Notice how many times in a phone pileup that the DX station will ask for the Echo Uniform or cw pileup EU? That is because you were the last station he heard. 

If you are running on cw, two or three stations on the same freq is uncopyable but you will notice the last couple of letters and work that guy. 

So far, other than knowing there is some latency, it has not had any impact on my operating. Should it be improved as much as possible? Yes, I would agree. 

I was more concerned about turnaround time. The time it takes to go from TX to RX. In SO2R, I am very impressed how quickly the 6700 switches. The second I CQ on one slice, I am listening to the second slice. Once done CQing, I am now instantly listening to the first slice. Is there a real delay? Yes, but not perceptible or meaningful in real time operating.

You can actually listen full duplex in SO2R, so no actual noticed delay unless you are near your harmonic. 

73, Craig K9CT

 
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Barry N1EU

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First off, big congrats Craig to what I believe is the best showing ever (at least in USA) in a contest using a DDC/DUC xcvr.  I agree with everything you said but there is still a real downside to the receive latency for my contesting.  When I'm trying to break a hellacious pileup on a needed multiplier, and I'm hearing the dx well, I feel that precise timing of my calls is a big advantage to punch through.  That's the edge I would lose with 165msec receive delay. 

I just ran some more experiments.  Latency drops from 165msec to about 100msec when I increase to 422Hz bandwidth.  I then ran some passband plots to look at the slopes and compared them with my Orion II (roofing filter plus dsp at their steepest setting of "199 taps").  Yes, the Flex filter slope is slightly shallower at 422Hz than 400Hz, accounting for the lower latency.  BUT the Orion filter slope is MUCH shallower still than even the 422Hz filter slope.  I would post some plots but the only software I have available produces logarithmic traces and they look a little strange.

This data seems to indicate that Flex has really skewed the filtering to extremely steep filter slopes without offering the option (yet?) of shallower slopes. Steep filter slopes are great when I'm tuning a crowded band or I have major QRM on the side when running.  But otherwise, shallower filter slopes comparable to what's being provided in rigs like the Orion II and K3 will result in MUCH lower latency and would also allow me to hear off-frequency callers, which I generally want.  On another note, when I'm just cw ragchewing, I really prefer the tone of a shallower sloped filter.

73, Barry N1EU
(Edited)
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km9r.mike

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Please do not take this the wrong way and I hope you do the same so you will agree. While working a contest pileup I go from loudest to weakest. I think it is just human nature to be lazy and work the easiest stations first.. Even if I get a quick prefix that is subsequently covered by a loud full call , I will default to the loud full call unless the prefix copied was a multiplier. I am not saying that your calls are not loud, at the worst I am just saying there may be louder stations calling at the same time and the station being called also goes from loudest to weakest as well.

At the same time, I think a leading edge technology machine like the flex SS rigs should be the envy of other manufacturers when it comes to measurements like this and am disappointed that they currently are not in this particular measurement. : (

(Edited)
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Andreas Junge, Elmer

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Barry,

thanks for measuring this! BTW, would it be possible to get the numbers for the "Remote" setting? To me it feels like it adds  another 150 to 200ms.
 
73, Andreas, N6NU
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M0GVZ

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The delay is irrelevant, really truly it is. In fact it may actually help you as I've always found that as a low powered station and operating mobile I get a lot more success being the "tail end Charlie" as it were so that the tail end of my transmission gets heard after the cacophony of noise from everyone braying away has subsided. "Station with victor zulu in the call"  or "station with golf victor zulu in the call" is often what I hear from the station running the frequency.

Look through my videos on Youtube. You'll see I get through pile ups usually in the first couple of calls. You'll also notice I repeat my callsign twice to ensure I'm tail end charlie. One of them, the one with the President Lincoln where I get through a pileup to AU3NIAR I'm only running 21W into a Hexbeam and manage to get through second call. 

At the end of the day though the biggest delay is actually in the operator. 
(Edited)
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W7NGA

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Too funny .. whoda thunk the day would come where adjustable latency becomes a feature?
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Barry N1EU

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The delay is irrelevant

It's irrelevant to YOU.  Several cw contesters have contacted me off-line and told me it's not irrelevant to them.

73, Barry N1EU
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M0GVZ

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Then quite frankly they're as dillusional as everyone else who thinks it makes a difference or they're trying to come up with excuses as to why they've not done that well. Stations don't answer calls that start to get sent 50ms before others, they answer the ones they can hear enough of a complete or partial of. 

Here's how asinine the argument is and the that of claims your friends are making. At 20WPM a dit is 50ms. Being generous and assuming a 50WPM send rate then at most they're a dash behind the fastest person who gets their transmission out first. And that's at 50WPM. That is nowhere near a good enough difference to be the make or break between making a contact or not. 

And if its so critical I assume you're all using CW keyers that are analysing the RX audio for the millisencond the last dit is sent so you're not wasting time with the 0.7 seconds of human reaction time so there isn't a single millisecond wasted more than is needed or are you wasting time reaching for the function key on the keyboard or the paddle/key?

Yours sincerely, someone who holds a first in world in class certificate for a CQ-WPX-RTTY contest and a bunch of first in class in England for contests including CQ-WW, CQWPX, IARU HF World Championship and ARRL International DX and who ranks consistently in the top 20% of all entries despite only running 100W, an inverted L and a Hexbeam at 36ft.
(Edited)
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Barry N1EU

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sorry, not buying it; 165msec is more latency that many somewhat fast cw contesters want to compete with

The cw filter slopes can be softened a bit by going to slightly over 400hz BW and turning on APF10.  But I suspect the APF might add even more latency.

Anyway, how did they get the latency down to 70msec on ANAN when they're even dealing with an ethernet roundtrip transport of the data since dsp is in the pc and not rig's FPGA?  Sure seems like Flex should be beating ANAN.
(Edited)
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km9r.mike

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I am gonna have to side with M0GVZ on this. While I would definitely like to see Flex SS rigs have industry leading numbers wrt this issue, in the big scheme of things how big of a detriment are the current numbers wrt real world operating ? The only direct experience I have with this and I think it is noteworthy is operating the weekly NCCC cw sprint events. I think the bigger detriment for me is my ocf dipole at 35 feet, but that works out even better for this discussion. I mention the cw sprint events specifically because of their unique rules. A station can not sit on a freq and run stations. Once a qso is made they must qsy so if you do not get that station before another station does you are SOOL and must find someone else to work.

 Ignorance can be bliss and I had no idea our rigs were so slow but not knowing this I operated them with the understanding that they were just as quick as the next rig. While my qso totals are about one half of the top scores in these events, I think this is more of a reflection of my antenna's performance and lack of experience in these events compared to the top scorers. In other words, I am not getting beat out consistently while answering a cq because my Flex SS is so slow. I am able to win my fair share of qsos by beating the other guy to this critical punch. Now if this is indeed an issue, I need to start playing my rig's handicap and should start transmitting as soon as I start to hear the last dah or 3 dits being sent by the station calling cq.

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M0GVZ

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What I find funny is that some of those "contesters" complaining about latency run a radio with DSP which has latency no matter whether its an old Yaesu FT1000, an Elecraft K3, a Kenwood TS590 or a Flex 6000, run an amplifier which introduces its own latency and will run full break in which increases it even more. If 50ms latency was the make or break they're claiming it is they'd be running a non-DSP radio such as a Kenwood TS850 in semi break in and barefoot. 
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Andreas Junge, Elmer

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I think this is besides the point. For one, I like to decide if I am tail-ending when calling and not leave it to the radio. It's about what can be done vs how it is implemented right now.  Barry has shown that if the filters are set to 422 hz width the latency drops by 65ms. The steep filter curves come at a certain price and I am willing to pay most of the time, but not always. If I get an option to select a filter shape of steep vs shallow with the resulting effect of high vs low latency then I can decide.  

I am also comparing a remote K3 with RemoteRig to the "Remote" audio setup of a Flex 6700 and the delay on the Flex is WAY higher than the RemoteRig.  It feels like there is a 150 to 200 ms added on top of the necessary delay dictated by the filtering. I think there is room for improvement. RemoteRig can do it well....

73, Andreas, N6NU
(Edited)
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M0GVZ

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A remote rig isn't having to process a ton of data. Its processing at best about 3kbit/s, probably less than that. The K3 is also processing far less data. Quite simply its about the number of bits needing shifting and the Flex is shifting a load more than a K3 and RemoteRig.

As I've said earlier the additional delay is a dash at 50WPM. Hardly world ending or contest losing and if you're blaming that for not making contacts in a contest then you're just another bad workman blaming their tools instead of their lack of ability.
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Andreas Junge, Elmer

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Exactly. The remote Audio on the Flex should be as low latency as on a RemoteRig connection, which it is not. The decoding is already done, so the remote audio should only add a few MS to the whole stream. I am OK with the latency at the audio connector at the back of the radio. I think there is room to improve the "Remote" audio stream as part of the Maestro rollout and WAN remote in 2.0.

Why does it matter? While you may not be able to tell a difference, at lot of us can and do. You should be happy with the performance you got. Let the rest of us help this fine company to make the Flex 6K line of radios the best in the market.

Why leave performance on the table if it can be improved? The hardware can do a lot, so I don't accept mediocre performance. They can and will do better than that. Not in this version, but maybe next. The Elecraft K3 would not be where it is today if it wasn't for all the user input and Elecraft's willingness to listen to them. 

And yes, I do contest from a hill at 2000' with limited road access at times, so remote latency matters. 

So please let's make this less personal and more about the data.

73, Andreas, N6NU
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Walt - KZ1F

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Is this something even fixable or is it a side effect of SDR or SDR as implemented in the 6000 series verses PSDR?
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Lewis Cheek

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Good question, how about some input Flex?

Lew
N4CO
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Walt - KZ1F

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I, vaguely, remember Steve talking abt this at one point but I have a very hard time searching for specific posts in getsatisfaction. Someone should introduce them to Lucene or (Sol).
(Edited)
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Jay / NO5J

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M0GVZ

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" If I get an option to select a filter shape of steep vs shallow with the resulting effect of high vs low latency then I can decide.  "

But then given as CW ops seem to be the most vehement complainers (complain about people not sending uniform morse but then complain about perfectly spaced computer generated CW for example) it'll then be decided that this isn't good enough and you should have the same latency with the steep filters.

Actually thinking about it if you implement soft filters instead of a "anything outside of 14.030.00 to 14.030.400 will be completely ignored", that involves more maths and data processing than vertical skirts because you're then having to calculate different steps of attenuation at both decreasing and increasing increments. 

In the linked thread K5UA makes a very important point and that is that having steep skirts is far more important in a contest than the extra delay. The only reason I bought a Flex for contesting is because the filtering of mechanical filters and DSP filtering implementation in conventional receivers is quite simply not good enough. The turnaround time is of no consequence to me until it starts to be measured in seconds. Far more time is wasted having to repeat information either way because a nearby station is overwhelming the station I'm in a QSO with than a 150ms latency will ever cause. 

Would it be nice to have a lower latency? Probably if that is a thing that floats your boat. Are the vast majority of users likely to notice any difference? No. Only those more interested in numbers on a bit of paper rather than real world effect are going to be concerned.

I'll leave with this final point. It is interesting to note how many people were completely unaware of any issue until the QST review mentioned it, such is how little impact it has.
(Edited)
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Barry N1EU

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Can you please repeat the point that K5UA made or tell me how to find it?
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Walt - KZ1F

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Good memory Jay! And / or you have mastered search arguments in GetSatisfaction. In either event, I believe that is what I was recalling, Thank you!

One thing I would caution folks about. If someone says or implies their sense is that <such and such>, they are not wrong, it is a general feeling of how well something is to them. Sure, there may be things that aggravate or mitigate the effect as M0GVZ and Steve point out, but the 'take away' for an individual is not wrong, as that's how they feel about the subject. Devolving a thread into personalities and blame serve no useful purpose.
(Edited)
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Jay / NO5J

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My search terms were, Latency N5AC KZ1F, I figured if you remembered it, you might have participated in the discussion. I had a feeling you were referring to N5AC, but there are plenty of other Steve's so I used callsigns which many people sign their post with. I got lucky! after I posted the link it seems those terms are less lucky. Now this thread tops the results, where before it was 4-5 down the results list.

A guide about better search terms would be nice.

73, Jay - NO5J 
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Walt - KZ1F

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ya know what? You are absolutely right, that didn't even occur to me, Wordpress Steve. But, I don't recall being part of that conversation as I am not at the point where even 500ms would make a difference in my success or failure to make a CW contact...Cool, I can blame SSDR or SDR in general from now on. Yes, Jay, I was referring to "the Zen of Flex" Steve.
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N9VV

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I am very interested in the Latency issue. One factor that I find very disturbing is that the ARRL has eliminated or discontinued their "TOR" test for PACTOR and AMTOR TRx operation.  These modes are now obsolete.  But for SSB operators, it points out that the Boat Anchor gear was designed to send a signal, switch back to Receive and then Respond within 20ms to the transmitting station.

TOR capable rigs are truly a delight to operate on CW using the examples for working DX that Barry presented earlier. Please do not throw away the "TOR" test/criteria just because *NONE* of the current rigs have that capability.

Latency is relevant to modern operation by operators who experienced the joy of true silky QSK in the past. When one is faced with spending $4K - $8K for a new rig, the Latency issue creates a truly major decision point. QSK is more of a necessity than just a preference for this operator.
thanks,
HNY de Ken N9VV
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Barry N1EU

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Interesting Web page with latency measurements:  http://www.n1kdo.com/sdr-delay-measured/

Barry N1EU
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Andrew O'Brien

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Very interesting
Andy K3UK
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Lewis Cheek

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Confirms what most of us knew, hope it improves soon.

Lew N4CO
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Chris Tate - N6WM, Elmer

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Barry just an fyi all the items we discussed back when you originally started this thread, latency, cw sidetone, adding MOX to the automated cw tx,  etc. are still on a "most wanted" features list for implementation.  After the Maestro smoke settles I am quite optimistic that work will start to be done to loop back on a couple of these issues.  These guys did a full context switch to get the Maestro done and as soon as they get rested and come up for air hopefully some of these items will be addressed.  the flex team appear to be keenly aware of some of the current issues and I probably burned some "nice guy" credit hammering home the contester nit list.  lets let them come up for air and see what the next pass of enhancements bring.
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Kevin

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Today I found a practical if not obscure impact of high latency and a slightly different take on what might be important about latency.

I've been playing around with Faros from VE3NEA which monitors NCDXF beacons on 20 though 10 meters. I was hearing the signals but they weren't being recorded. After an email to VE3NEA I was told to adjust the delay correction so that recorded points cluster around the short path.

I did that with the filters set at their lowest latency and got a few points for each station. Then I move the filters to their sharpest setting and, roughly averaged, I was seeing about 156 ms of delay. The effect makes everything look like it is coming in on the long path. 

Obscure. I know.

But here's my takeaway from this little experiment. It seems that, within reason of course, predictable latency through the filters (through the whole rig for that matter) is more important than low latency when it comes to measuring paths.

I'm not good enough to even consider 156 ms as impacting my ability to make a contact. More often it is fumbling with the key or living with a less-than-ideal antenna that keeps me at the back of the pack. But it is nice to finally figure out how latency can be important. Today I feel smart. Tomorrow it's back to being a pain in the neck.

73,
Kev K4VD
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dl9eri/oe9eri

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Today I took my scope and measured the receive latency of the new filter
settings just for knowing how they work and found that I can now use the slider for equal latency in all choosen bandwidth and modes. The numbers are +- 5mS.

The numbers: left is 0 - 1 - 2 - 3 and auto

In 0 : all modes and bandwidth  55 mS
In 1 : all modes and bandwidth  75 mS
In 2 : all modes and bandwidth 105 mS
in 3 : all modes and bandwidth 165 mS

In the -auto- position of the sliders there are different latencies for the bandwidth in CW and DIGI
from 55mS on 3-5KHz, 75mS on 1KHz, 105mS on 800Hz, and <400Hz 165mS. On SSB in auto there is always 165mS latency but you can choose from sliderposition 0 to 3 to change.

note: it is the receive latency when your partner sends a -did- and you can hear it on the 6500 after the delay in mS

best 73
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Lee, Elmer

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I don't know if K5FR has developed a macro yet, but it's my understanding these filers are callable in the API, as are filter bandwidth to the hz and filter position in the pass band. With all of that available designing a filter around a given parameter like latency should be do-able. I have several custom filters in my macro table

73 W9OY
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Ria - N2RJ, Elmer

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I was at a friend's house yesterday doing some troubleshooting on his low band antennas and coax. For signal strength comparison we fired up my ssdr for IOS on my iPad and also his K3S. There was definitely a noticeable delay almost I would say 250ms or so. I am wondering if this is only in the app or in general?