[drats_users] ERROR Correction in slow speed data

[Joel Black]

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] *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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