Audio TX, what is the wrong config in my setup?

[DM5SB]

Dear remote friends,

my name is Stefan and I use a Remoterig HW version 6 since two weeks. I Use IC706 Mk2G. The previous owner of the rig used it with the same Hardware. I bought it as a set. So it may should work.

After replacing the modems by new fritz-boxes on both sites, the VPN network is working. I use Radio and Control in a DOCSIS Network. No public IP is necessary. The owner of the DOCSIS net is a "friend" of mine, so I could easy test every Up- and Download speed I wish. At the moment the radio has 2.6MB Upload and the control 4MB 


Ok - the Remote-Rig is working too. I have done some nice QSO. But with audio problems. It sounds like the Internet is not fast enough. But I can not imagine that the problem is there! Ping 10ms to 30ms due to other traffic. The VPN net goeas directly over the CTMS.



The audio on the RX sounds good, sometimes it falters but that does not bother. The net is fast enough to use a medium (and sometimes high) audio quality with acceptable interruptions. Ok. No problem. Thats the way I like it.

The audio at the TX is cruel. The stream does not sound continuously. It is choppy. Overdriven. Wagging.

What I try to fix the problem is to play with:
- audio Quality at both sites. different combinations, no big difference. same sample rate
- Codec gain in and out at both sites
- jitter buffer and delay at both sites increase delay but no better audio
- packet size at both sites increase delay but no better audio
- RF power: 2W or 100W no difference
- firmware update - no change

What I do not understand is why there are no noticeable differences in the big range of config combinations. I expected to find on optimum. But the TX sound is poor - always.


Please tell me, what information about my setup and configs do you need? Please help me to find the Problem in the TX way. I read the 250 pages of manual up and down, no further idea.

[DM5SB]

One thing I forgot:

I use COM Port to control a relay interface to switch the antennas.

[dj0qn]

Hi Stefan,

It looks like you may have already attempted to do a lot of tweaking, so perhaps there is not much
more than we can do for you. I assume the bottleneck is actually somewhere in the VPN somewhere,
so perhaps you should try the "normal" method of using port forwards for a test. 99%+ of the installations
are doing fine using this method, so perhaps give it a shot.

Anyway, I have a checklist that assists one with low-bandwidth situations. Again, I assume that you already
tried this, but this is about as best as I can help you at this time:

3G/4G Checklist
------------------
Try reducing your bandwidth to a minimum and changing some parameters to compensate
for a poor line. Note that this is only for using 3G/4G on the control side. Running a RemoteRig
system over 3G/4G with the router on the radio side will never work, unless you pay extra for a
true external IPv4 address or use a VPN.

Here are some tips:

1) These are important:
- audio quality to 0 (half the bandwidth of codec 2 and more than adequate for SSB & CW)
- turn continuous RTP on or set RTP to continuous (depending upon firmware version)
- If using the K3 Twin or Yaesu with a second receiver, then turn off "audio dual-rx" on the
   radio RRC under the radio settings. This doubles the necessary bandwidth if on.

2) Play around with these 3 until you are satisfied:
- increase rx jitter buffer to min 12+
- increase rx jitter delay to min 10+
- audio packet size 20 or 40

3) Also, make sure that serial ports COM1 and COM2 are turned off if not used,
or that either being used is set to the minimum bps necessary to handle the serial
communication. For example, use 4800 for CAT on a rig like the TS-480 and not
a high speed like 57600, since the higher speed is completely unnecessary.

73,
Mitch DJ0QN / K7DX

[DM5SB]

Hello Mitch,

thanks for the reply. 

I tested your checklist:

- RTP to Continuous
- the buffer settings
- turn off COM port

No difference. Hear the attached mp3 file. Thats how my TX audio sounds.



At next I try to play with the VPN network.
I will use the remoterig server. Do I need 2 different public IP for radio and control? Maybe I had to ask the owner of the DOCSIS net.


My last idea is to test the system with another TRX: Kenwood TS480. But before, I had to reconfigure the hardware and so on...

[dj0qn]

Stefan,

The audio sounds scratchy, as if there is not a good connection in the microphone chain. Note that
microphone audio is done entirely in hardware, using the red strappings in the RRC's. Make sure that
all are connecting properly using an ohmmeter. Never push these in by hand, always use a needlenose
pliers to hold just above where the insulation starts and push gently into the hole. If one gets bent, then
throw it away and make a new one.

Also make sure that you are using separate power supplies for the RRC and rig.

If using a VPN, all you need to use is the internal IP number of the radio RRC and not the external IP
number. That won't even work for a VPN, because the ports are not forwarded.

73,
Mitch DJ0QN / K7DX

[DM5SB]

Dear Mitch, thanks for the reply.

I checked the red straps: everything very tight, good electrical connection.
Separate power supplies: yes


After that, I decided to test it with the TS480. I changed the configuration in hardware and software (not the Network). Meanwhile, I drove countless times back and forth. But it was successful. The problem does not occur with the TS480. RX and TX audio are very good. 


So far I have not found out the reason why there were problems with the IC706. At the moment I do not have the time to test it. I am glad that it works at all.


I noticed that within the SSB bandwidth NF gives harmonics. This is not nice at digimode. I reduced the volume from the PC to almost 0. Reduced mic gain. Also, the voice processor was disabled. No noticeable improvement. Could this be a problem in the audio codex? Does anyone have experiences?
At next I will check the audio volume at the radio site.



Many thanks for the support
73

[dj0qn]

Stefan,

You should for sure try different CODECs. There was another thread on here recently that mentioned that
problem and it was solved by changing the CODEC.

If you have any further questions, just let me know. I can be contacted directly at dj0qn (at) darc.de
(die Sprache ist egal).

73,
Mitch DJ0QN / K7DX

[DM5SB]

Hi Mitch thanks for the help.


The TX audio harmonics, measured in the SSB RF signal, are 20dB lower than desired signal by using audio CODEC 1

With CODEC 2 the harmonics are 39dB lower than desired signal. I think thats okay.


I have noticed that the harmonics at very low volume of the PC do increase (still full power). It is best at 50% volume. This contradicts logic, but good to know.


With the new audio setting, the LAN traffic is higher, I have to check the quality...