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High Loss% with ThumbDV on DMR
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Patrice Quilici <f1hmr@...>
The new key work very well on Mac and PC Many thank’s 73’s F1HMR Le 25 janvier 2018 à 22:45:08, Bryan Hoyer (bhhoyer@...) a écrit:
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Patrice Quilici <f1hmr@...>
Thumb DV well arrived look work nice many thank’s for all P.QUILICI-F1HMR Le 25 janvier 2018 à 22:45:08, Bryan Hoyer (bhhoyer@...) a écrit:
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👍
On Jan 28, 2018 06:00, <tcorcoran@...> wrote: All,
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All,
to bring closure on this thread ... I saw the hi Loss% on two repeaters which both happened to be running Pi-Star. In MMDVMHost, we increased the jitter from 300 (default) to 700 and Loss % is consistently 0% now. AND great audio reports. Tnx for everyone's constructive advice. Much appreciated. ThumbDV is a great performer and suits my need for a convenient travel package. I look forward to future product enhancements. Now returning to regular programming .... with repeaters and hotspots!! Tom VE3NY
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One thing we ran into on some hosts was the latency timer on the FTDI serial driver. I want to repeat, on SOME hosts. Take a look as root: cat /sys/bus/usb-serial/devices/ttyUSB0/latency_timer it may be set at 16. set it to a 1 and re-test.
73, Steve N4IRS
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Tnx David and all others. Will assess internet parameters. In meantime, I think I will contain my use of ThumbDV for DStar ... appears that I have no issues on that mode ... Tom VE3NY
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Hi All, I will try to explain. What happens when you sent to the DMR master/reflector. Every 20ms I receive a DMR voice frame of 72 bits from the ThumbDV. I wait until I have 3 frames. Then I add some extra spicy saus for DMR data ( 48 bits ) ( EMB etc ). It is not normal to use TCP as a transport for voice. When you have loss it will re-transmit. And retransmitting is latency or jitter. Jitter is really bad for voice! There are several tools on internet to test the latency, loss etc. A good internet connection from end to end is very important for voice! ---
Greets and 73, David PA7LIM
On 25-01-2018 23:24, John D Hays - K7VE wrote:
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Tom -- David (PA7LIM), author of BlueDV, participates on this list, so we may hear from him on this topic.
On Thu, Jan 25, 2018 at 2:22 PM, <tcorcoran@...> wrote: All, --
John D. Hays Edmonds, WA K7VE   
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All,
tnx for very constructive advice. I will pursue with s/w author. Tom VE3NY
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Brian,
not sure. Will check.
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Tom McDermott
Hi Tom, In my opinion this is not a hardware issue. The general problem is that the Internet hasWhat to do? Real time media devices sometimes use a special protocol such as RTP / RTCP to balance the tradeoff between loss rate and latency. If the internet path from the source to the destination (involving a lot of connections, routers, etc.) has loss and / or latency problems, that sort of has to be fixed first. -- Tom, N5EG
On Thu, Jan 25, 2018 at 1:39 PM, <tcorcoran@...> wrote: Tnx Tom,
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The software, in this case BlueDV, controls the packet flow to/from the ThumbDV. NW Digital Radio is responsible for the manufacture of the ThumbDV and that it performs according to the hardware specs and documentation. Software is responsible for transport of Audio (PCM) and AMBE to and from the ThumbDV hardware.
On Thu, Jan 25, 2018 at 1:39 PM, <tcorcoran@...> wrote: Tnx Tom, --
John D. Hays Director 
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Is HW flow control enabled? It is a requirement for the AMBE3000 Chip
Bryan K7UDR
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Tnx Tom,
this is is a thorough diagnosis and resolution of the problem. Is this something that should be fed back to NW? Or is DMR beyond the design spec of the ThumbDV? I understand conceptually what you have done but would be unable to build the interface to provide packet limiting on my own. Any "brite force" method of limiting packets? Is this something that the vendor could/should provide? I’m using BlueDV but not implying he should do anything. It’s a NW issue - correct? Tom VE3NY
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Tom McDermott
Hi Tom, I've written an interface for ThumbDV to gnuradio. It runs in DSTAR or DMRAMBE encoding/decoding mode without losses. Right now I don't have any modules written to insert or extract DSTAR bits from a raw 4800 BPS stream, nor to/from DMR. So testing is just loop-back: audio-input to AMBE encoded samples, those samples looped back to the decoder to audio output. In writing the gnuradio driver, I ran across one case where the losses were high. For me this occurred when over-running the ThumbDV with packets faster than a 20 milliseconds per packet rate. It was not enough to limit the packets-to-ThumbDV to the 460,800 bps serial rate, The device would lose synchronization at the packet level, and eventually recover after throwing away enough corrupted response packets. Then after a few good packets it would get lost again. The device latency appears to be about 3 packets, so it is necessary to pipeline the packets. It ended up being necessary to limit how many packets are inside the ThumbDV. My driver limits the number of packets inside the device to 5, it seems to run OK with that. -- Tom, N5EG
On Thu, Jan 25, 2018 at 10:34 AM, <tcorcoran@...> wrote: Mike .. good suggestion and tried it ... no luck. still hi loss % 0% BER and Loss figures are all over the map from 0% to 80%. I have tested on DMR/BM and DMR+ with same result. D-Star works fine and "some" TG's are ok. Have also tried other pc's ... same result.
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Mike .. good suggestion and tried it ... no luck. still hi loss % 0% BER and Loss figures are all over the map from 0% to 80%. I have tested on DMR/BM and DMR+ with same result. D-Star works fine and "some" TG's are ok. Have also tried other pc's ... same result.
Do either of you or John (or others) have a ThumbDV and, if so, are you experiencing this issue? Tom VE3NY
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Sounds a lot like streaming issues when connected to the Internet over a marginal wireless access point or low bandwidth connection. If you're using public WiFi when experiencing this, there's not much you can do. But if you have unlimited data, try creating a WiFi hotspot with your smartphone.
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Thanks for suggestions .... I will try John's suggestions on sending a ping from my pc to a selected reflector. Michael, I have tried both plugging into the pc directly as well as using a powered USB port. Same result. Tom VE3NY
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Mike.WB4TTZ
Plugged directly into the PC or into an external hub? You may not have enough current capacity to effectively power the ThumbDV. Try it plugged directly to the PC. Mike, WB4TTZ
From: John D Hays - K7VE
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Which software are you using with the ThumbDV? The ThumbDV only deals with serial communications over the USB port. It is extremely unlikely that any bit errors could be introduced at the USB interface between the computer and ThumbDV. Bit errors tend to happen in the transport layer, eg. over the air on a weak or interference prone signal, in the modem (which would tend to be a radio), or most likely what you are seeing is UDP packet loss -- if you are seeing packet loss -- I think most dashboards are expressing loss in terms of percentage of packet loss rather than BER. You may want to run ping between your computer with the ThumbDV and the reflector's IP address (You can find them at https://ar-dns.net) and see what the packet loss is when you kill or stop the ping. For Windows https://datapath.io/resources/blog/how-to-test-for-packet-loss-on-windows/, on Linux or MacOS, just use the command line ping and run it for a while and then hit Control-C and look at the stats.
On Wed, Jan 24, 2018 at 11:07 AM, <tcorcoran@...> wrote: Have been using DMR/DStar for couple of years now but I recently acquired a ThumbDV for travel and am generally pleased. However, when I check reflector dashboards, I note high Loss % (yet 0% BER) when on DMR. The loss % is quite volatile as well (5 - 50%). Other stations registering 0% Loss and 0% BER. Anyone else have this experience? --
John D. Hays Edmonds, WA K7VE
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