[drats_users] ERROR Correction in slow speed data

[Joel Black]

Thanks, Matthew.  Sounds like the manufacturers of our VoIP equipment 
need to use the AMBE voice chip.  :)

73,
Joel - W4JBB

On 9/20/13 5:47 PM, Matthew Pitts wrote:
> Joel,
>
> Conventional VoIP probably doesn't, but D-Star and other similar 
> systems don't follow those rules; the FEC is actually handled by the 
> AMBE Vocoder chips through firmware programming.
>
> Matthew Pitts
> N8OHU
>
>
> ------------------------------------------------------------------------
> *From:* Joel Black <w4jbb at charter.net>
> *To:* Discussion of D-RATS <drats_users at intrepid.danplanet.com>
> *Sent:* Friday, September 20, 2013 6:23 PM
> *Subject:* Re: [drats_users] ERROR Correction in slow speed data
>
> Okay, this goes against what little I have learned about VoIP traffic.
>
> I didn't think there was any FEC with voice.  That's why voice has 
> priority on data networks that use VoIP.  Otherwise, if a data packet 
> has priority, it would bump a voice packet.  When a voice packet is 
> bumped, you lose bits of it resulting in choppy audio.
>
> I have experienced this when some of our first quasi VoIP locations 
> came online.  Voice is live traffic. Once it is said, it goes.  
> There's nothing to re-transmit.
>
> Without getting into the engineering (which will leave me drooling and 
> nodding off to sleep), how does D-STAR use FEC on voice?
>
> 73,
> Joel - W4JBB
>
> On 9/20/13 3:57 PM, John Davis wrote:
>> That is true. The FEC is on the voice with 2400 bits for voice and 
>> 1200 for FEC.
>> John WB4QDX
>> *From:*drats_users-bounces at intrepid.danplanet.com 
>> <mailto:drats_users-bounces at intrepid.danplanet.com> 
>> [mailto:drats_users-bounces at intrepid.danplanet.com] *On Behalf Of 
>> *Daniel Metcalf
>> *Sent:* Friday, September 20, 2013 4:55 PM
>> *To:* Discussion of D-RATS
>> *Subject:* Re: [drats_users] ERROR Correction in slow speed data
>> Agreed. From what I have read d-star is a lot like the UDP network 
>> protocol where it is transmit and forget there is no handshaking / 
>> error correction built in. It is up to the application developer to 
>> handle error correction and the d-rats package does perform some 
>> level of error correction.
>> Dan Metcalf - KB3UUN.
>> On Sep 20, 2013 3:54 PM, "John Davis" <jdavis at gtworks.com 
>> <mailto:jdavis at gtworks.com>> wrote:
>>
>>     My understanding is that the low speed data channel does NOT have
>>     error correction, however, D-RATS offers Error correction in
>>     Message and File Transfer modes where it is most important.
>>     John WB4QDX
>>     *From:*drats_users-bounces at intrepid.danplanet.com
>>     <mailto:drats_users-bounces at intrepid.danplanet.com>
>>     [mailto:drats_users-bounces at intrepid.danplanet.com
>>     <mailto:drats_users-bounces at intrepid.danplanet.com>] *On Behalf
>>     Of *Dave Welker
>>     *Sent:* Friday, September 20, 2013 3:19 PM
>>     *To:* D-Rats Mailing List
>>     *Subject:* [drats_users] ERROR Correction in slow speed data
>>     Hello all,
>>     Can anyone confirm if the D-RATS slow speed data has FEC (Forward
>>     Error Correction) built in now or not?
>>     I understand that D-STAR voice does have error correction built
>>     in.  I've checked on the D-RATS home page/documentation
>>     which is a August 2009 reference.
>>     This is what I found in this document Under users manual/files:
>>     Is this still current information?
>>     *Unlike the D-STAR DV Voice Channel, which has error correction
>>     built into the protocol, the Data Sub-channel has no error
>>     correction. *
>>     *This makes the transfer of data across D-STAR a lot more
>>     dependant on a good radio path being established between the two
>>     locations wishing to *
>>     *exchange data.  D-RATS includes the ability to test connectivity
>>     between two locations**.*
>>     Thanks in advance
>>     regards
>>     Dave
>>     W2SRP
>>     Goals are where we want to be;
>>     Objectives are the steps to get there.
>>     There are 2 rules to success in life:
>>     1. Don't tell people everything you know.
>>
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>>
>>
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