the 'A' is typically the toughest digit to decode among with the '5'.
These are the digits that have the largest tone deviation.
Another problem source could be the Radios audio level.
Not knowing what Radio it is, it may have de-emphasis circuitry where it
shouldn't. How is it interfaced? if there is any other audio processing
going on, it may reshape the audio wave in such a way that the SVXLINK
decoder is asked to do more than it can.
Where is the audio picked off? If it comes from an accessory connector,
the received audio is already processed through the Radio since this
type of connector was originally meant for packet and not voice. Many
manufacturer implement a filter that re-shapes the signal for packet.
Audio would sound more muffled. The filter rolls off at much lower
frequency at -3dB. Just about enough to mess with the DTMF tones.
If the audio source is the Speaker Out from the Radio, there should be
in general no problems aside the level.
It is a little tricky to comply with all the Industry standards and yet
have it universal.
If you set your audio source to 0dBm (750mvpp) it is usually too hot for
the soundboard (Voice). If you set it too low, the DTMF decoder will not
work properly because the standard input level is 0dBm.
On a accessory connector (packet) your audio level maybe at 500mvpp
(when using 9600 Baud) and barely at 350mvpp (when using 1200 Baud).
These are fixed levels.
In both cases above, the DTMF decoder gets into trouble while the
500mvpp may work. As far as I remember, Tobias did adhere to the
industry standard as much as possible.
I think Adi has made the right suggestions, and in my opinion the Radio
should be exchanged with an other on (different manufacturer) if
possible at all. I believe it is the Audio level combined with some
weird filter implementation before it gets to SVXLINK for decoding.
Concluding, whilst in general working acceptable it is not really the
optimum to supply the Voice audio and the Decoder audio at the same
level because there are two different requirements.
Visit the Website at
On 9/10/2010 01:19, Adi Bier wrote:
> Danny Moss schrieb:
>>> Danny Moss schrieb:
>> Hi Adi, a the Group,
>> Thank you very much for your responce to my cries for help ok first problem
>> I have adjusted DTMF_MAX_FWD_TWIST in your [Rx]-section and started at
>> 10 and went right up to 40 I am now sitting on 17 as yourself this now
>> decodes all but the A so I can now decode 1 2 3 4 5 6 7 8 9 0 # B C D
>> just cannot seam to get A but I dont think that will matter I will keep
>> checking this and see if I cant fine tune it abit more but for most of the
>> commands it is working.
> Hi Danny,
> it's a bit amazing that you can't decode just a single digit. Here I can
> only recommend to try with another radio with dtmf, just to check that
> it is a problem of the svxlink dtmf decoder. The software dtmf decoder
> works really well but I see the problems in the enormous number of
> different ham radios with varying dtmf-levels, modulation, frequency
> responses together with different soundcards, adapters and so on. So the
> only chance is to find an optimum that covers the rig that usually used
> in hamadio field.
>> 2 Second problem ( I might not explained myself correctly sorry)
> as Norbert wrote before, it may be a problem with your configuration.
> It's not possible to run two different machines behind a dsl router
> without any problems. To exclude that it is such a problem, please
> conduct the next steps:
> - start svxlink on your linux machine, brinf down the windows pc
> - double check that your router configuration is correct and the port
> forward points only to the IP of your svxlink server
> - connect to the echolink testserver and check that your audio is
> playing back to you
> - please send your log /var/log/svxlink (just the last lines from the
> svxlink-startup including the connection to the testserver)
> - what version of svxlink do you use?
> 73's de Adi, DL1HRC
>> I changed the fire wall setting before looking and of course mucked things
>> up then checked and saw that the rules was already there and of course
>> this system worked till I changed the radio over and had to change
>> connections on the interface.
>> So I don't think it is a firewall problem but I could be wrong.
>> now to better explain my problem
>> It seams to be only the audio coming from the radio side of things
>> what I do to test my system I have my normal echolink account vk7hdm and I
>> have my svxlink account vk7hdm-L
>> so Using svxlink from the keyboard I send
>> 2 #
>> then I dial my vk7hdm system
>> 2 1 3 5 #
>> It connects to my vk7hdm (windows system) and I can hear svxlink
>> announcement (I get and Audio Bar)on that system but the moment I pick up
>> my hand held and call myself I don't get a audio level bar in echolink on
>> the windows machine and no audio.
>> I can disconnect and get the announcements on the windows machine.
>> So then I use the handheld to open the link to my windows system vk7hdm-l
>> I send the dtmf
>> 2 # I hear the announcement from svxlink over the radio I then send
>> 2 1 3 5 # to connect to my windows system vk7hdm
>> and both on the radio and on the windows system I hear the announcements
>> that I have connected but I then key up the hand held and speak and
>> nothing no audio or a Audio bar in my echolink windows machine even if I
>> just key up the handheld with out speaking there is no Audio bar at the
>> bottom of the screen in echolink ion the windows machine
>> Here is a cut and paste of my fire wall
>> Accept If protocol is UDP and destination port is 5198 and state of
>> connection is NEW
>> Accept If protocol is UDP and destination port is 5199 and state of
>> connection is NEW
>> Accept If protocol is TCP and destination port is 5200 and state of
>> connection is NEW
>> My System is Linux Fedora 13
>> If anybody wants to have a look at my svxlink.conf I can send that as well
>> incase I have a problem there.
>> Any help is very much appreciated in this matter
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