- Posts: 3
Jumper T8sg and E010s flysky AFHDS = latency
12 Oct 2017 10:24 - 12 Oct 2017 10:38 #64979
by goebish
Replied by goebish on topic Jumper T8sg and E010s flysky AFSDH = latency
Hi, I'm the developer of the AFHDS 2A protocol, not AFHDS 
I've just received a Flysky E010S (thanks Fred !) and there's no problem with my T8SG, no latency, everything works perfectly on my end.
The same machine with Fred's T8SG has the latency issue.
I'm not sure what the problem is and it seems you're not the only one to have this issue.
I'd like to make a test build with configurable packet interval, just to try, vlad_vy, I had a look at your github but I can't find a branch for the T8SG, is it available somewhere, is there a reason it's not available in master branch yet ?
I've just received a Flysky E010S (thanks Fred !) and there's no problem with my T8SG, no latency, everything works perfectly on my end.
The same machine with Fred's T8SG has the latency issue.
I'm not sure what the problem is and it seems you're not the only one to have this issue.
I'd like to make a test build with configurable packet interval, just to try, vlad_vy, I had a look at your github but I can't find a branch for the T8SG, is it available somewhere, is there a reason it's not available in master branch yet ?
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12 Oct 2017 10:47 - 12 Oct 2017 10:47 #64981
by goebish
Replied by goebish on topic Jumper T8sg and E010s flysky AFSDH = latency
Ok, that's what I thought but I wasn't sure, I'm just coming back from holidays
Would you commit it on your github (new branch) or just send your sources to me for test purpose ?
(myname @gmail.com)
Would you commit it on your github (new branch) or just send your sources to me for test purpose ?
(myname @gmail.com)
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12 Oct 2017 11:05 - 12 Oct 2017 11:05 #64983
by goebish
Replied by goebish on topic Jumper T8sg and E010s flysky AFSDH = latency
Thanks very much vlad_vy !
Oh, I've just tried with my 2nd T8SG (the first model, with unattainable USB connector
) and it exhibits the same issue, loss of packets (blue led blinks on the E010S) and extreme latency that makes it uncontrollable.
I've to check if I've the same issue with other A7105 protocols (Hubsan, AFHDS 2A) or if only the AFHDS protocol is affected.
Oh, I've just tried with my 2nd T8SG (the first model, with unattainable USB connector
) and it exhibits the same issue, loss of packets (blue led blinks on the E010S) and extreme latency that makes it uncontrollable.I've to check if I've the same issue with other A7105 protocols (Hubsan, AFHDS 2A) or if only the AFHDS protocol is affected.
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12 Oct 2017 12:57 - 12 Oct 2017 18:12 #64988
by goebish
Replied by goebish on topic Jumper T8sg and E010s flysky AFSDH = latency
I tried tweaking packet interval (it was changed ~1 year ago to match new AFHDS transmitters, see
here
) but that doesn't change anything 
Hubsan protocol (A7105 as well) works without any issue but this protocol does not have any frequency hopping, so I suppose it's more resilient to packet loss.
I'll try AFHDS 2A ...
Hubsan protocol (A7105 as well) works without any issue but this protocol does not have any frequency hopping, so I suppose it's more resilient to packet loss.
I'll try AFHDS 2A ...
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12 Oct 2017 13:52 #64990
by goebish
Replied by goebish on topic Jumper T8sg and E010s flysky AFSDH = latency
Well, I suppose it's time to grab the HackRF to understand what's happening 
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12 Oct 2017 15:38 - 14 Oct 2017 12:30 #64994
by goebish
Replied by goebish on topic Jumper T8sg and E010s flysky AFSDH = latency
All I can see with SDR is that the working T8SG and the Devo 10 has an almost perfect gfsk center frequency (only +30kHz drift, and it could be my HackRF that's not calibrated ...):
(working T8SG and Devo 10 captures are ~similar)
while the non working T8SG has a +80 kHz drift compared to the working ones (110 kHz in total):
Both signals look pretty similar, only shifted in the frequency axis.
That's probably due to the (non) accuracy of the crystal oscillator they're using for the A7105.
I'm not sure this can be an issue, I think the RX side should have enough selectivity to cope with that, but maybe it's on the edge and most packets are not received ...
edit: I've also tried to swap antennas, but same result.
(working T8SG and Devo 10 captures are ~similar)
while the non working T8SG has a +80 kHz drift compared to the working ones (110 kHz in total):
Both signals look pretty similar, only shifted in the frequency axis.
That's probably due to the (non) accuracy of the crystal oscillator they're using for the A7105.
I'm not sure this can be an issue, I think the RX side should have enough selectivity to cope with that, but maybe it's on the edge and most packets are not received ...
edit: I've also tried to swap antennas, but same result.
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12 Oct 2017 17:06 - 13 Oct 2017 21:22 #64999
by goebish
The A7105 has a frequency compensation function, but only in Rx mode (see chapter 14.3 in A7105 datasheet), unlike the cc2500 & cyrf6936 there's no way to fine tune the frequency in software on Tx side
... I've an old 4-in-1 module, I've never installed it in my Devo 10 because it's the first version with non working LNA on nrf24 & a7105, I think I'll try to swap it with the one in the non (well, almost) working T8SG to check if that's the problem.
... let's grab the hot air rework station now.
edit: A7105 Tx frequency can be fine tuned with registers 0x11, 0x12 & 0x13, the nrf24l01 is the only radio on which we can't fine tune Tx frequency.
Replied by goebish on topic Jumper T8sg and E010s flysky AFSDH = latency
... I've an old 4-in-1 module, I've never installed it in my Devo 10 because it's the first version with non working LNA on nrf24 & a7105, I think I'll try to swap it with the one in the non (well, almost) working T8SG to check if that's the problem.
... let's grab the hot air rework station now.
edit: A7105 Tx frequency can be fine tuned with registers 0x11, 0x12 & 0x13, the nrf24l01 is the only radio on which we can't fine tune Tx frequency.
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