Re: Bridging the digital voice and data gap

Matthew Pitts <daywalker_blade_2004@...>
 

Tyrell,

The transcoding between AMBE and Codec2 has been done by Kristoff ON1ARF; his blog has some sound samples that I have listened to. I will admit that they may not be the neat sounding speech with multiple conversions, but it's still a lot clearer than analog signals from a fringe area into an analog repeater.

As an update, it appears that AMBE to AMBE should be fairly easy, especially between D-Star and NXDN; there appears to be only a difference of 50 Hertz in the sampling rates, and a similar difference in the error correction. I will have to research the difference between D-Star and DMR next.

Matthew Pitts
N8OHU


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From: Tyrell Berry ;
To: Subject: Re: [UniversalDigitalRadio] Re: Bridging the digital voice and data gap
Sent: Fri, Aug 3, 2012 2:00:31 PM

 

Again, I'm not an audio engineer, and I have been wrong before...  but isn't saying that the chip is a vocoder and it is not compression kind of like saying MP3 is a Muscoder and is also not compression? Is it somehow true that because someone chooses to use a different vocabulary that the principles of which I speak somehow cease to apply?

It has been said several times before, and I will agree: it's entirely possible that transcoding through back to back vocoders may produce legible audio...  Only one way to find out, and I look forward to hearing recordings of the results.  

On Aug 3, 2012 6:51 AM, "Bryan Hoyer" <bhhoyer@...> wrote:
 

The UDR56K has an expansion interface which is designed for an optional ambe vocoder (it is NOTcompression).

DVSI chips are TI DSPs that are factory programmed with their code. The interface is 2 SSPs or synchronous serial port which connect directly to the Marvell SOC.

The interface and drivers wil be documented.

Bryan

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