Re: DVAP and the DVRPTR boards


 

D-STAR is a protocol.  The protocol has an open specification that has been implemented in open source software.  Within D-STAR are sub-protocols and specifications.  The vast majority of D-STAR's protocols and specifications can be implemented in open source.  One of those specifications is the Vocoder for Digital Voice.  That specification calls for a version of AMBE, the most widely used method of vocoding.  When the specification was written there wasn't anything generally available for vocoding that competed with it, which is why it is in APCO25 (Phase 2), DMR, NXDN, etc --.AMBE is proprietary and licensed technology of DVSI, which can be obtained in firmware on a dedicated DSP chip for a few dollars.

CODEC-2 only became generally available in the last year and still requires a significantly powerful processor to run the algorithm.  It does not, at this time, run in realtime on the Raspberry Pi. It might if it was rewritten using fixed point, but the developers have chosen not to do that.  The most likely implementation of CODEC-2 for Raspberry Pi will be a DSP daughter card (much like the AMBE chip) to run the algorithm and provide a radio interface, leaving the Pi to provide the user interface and networking support.

The argument that ham radio can't use proprietary, licensed,  or closed technology is ridiculous at best.  Let's take the logic and apply it to amateur radio.

Let's say CODEC-2 was optimized sufficiently to run on the Raspberry Pi. If no proprietary, licensed, or closed technology could be used, you couldn't run it on the Raspberry Pi -- which uses a whole bunch of licensed and proprietary technology.  Even the processor itself uses ARM, a licensed and proprietary architecture -- see http://www.arm.com/products/buying-guide/licensing/index.php and some of the drivers have been closed source based on Broadcom NDAs (Non-Disclosure Agreements).   Other subsystems in the Broadcom SOC (System on a Chip) processor in the Raspberry Pi are similarly licensed intellectual property of Broadcom and others.

Let's look at other technologies that are (or were) patented and proprietary and used widely in amateur radio.

Every microprocessor, display, and almost every discrete component in a radio.

A read of https://en.wikipedia.org/wiki/History_of_radio will show that CW, AM, FM were all patented inventions.


This is true of almost every aspect of radio telecommunications.

The original question was around 

"Can someone recommend a place to buy a raspberry pi board and the correct
version / part number? I am looking to build a DVDongle - Pi box"

People simply provided various sources for the Pi, and the below referenced email simply provided additional devices that could be used with the Raspberry Pi  to provide D-STAR connectivity

All of these are for a gateway/hotspot to allow someone with a D-STAR radio connectivity to the rest of the D-STAR network via the Raspberry Pi.  None of them require the AMBE chip (one has it as an option).

The arguments express ignorance of the technology and applications -- Amateurs should do better than that, providing technically and logically correct answers.  Leave misinformation and deception to the politicians!

If you don't like D-STAR, simply state it, but making false arguments doesn't leave much credibility.  It's OK to not like something, but allow others to learn about and make up their own minds about it.



John D. Hays
K7VE
PO Box 1223, Edmonds, WA 98020-1223 
  




On Thu, Jun 6, 2013 at 8:36 PM, Mathison Ott <mathisono@...> wrote:
 

D-star isn't even opened source!  Were is the codec2 mode for the RPi?

73 Kj6dzb
Mathison



On Thu, Jun 6, 2013 at 7:19 AM, John Hays <john@...> wrote:
 

Not one of these has a vocoder (AMBE) to do the gateway/hotspot function and all can run using open source.






Sent from Samsung tablet

Dave B <dave@...> wrote:
 

On 6 Jun 2013 at 8:57, Raspberry_Pi_4-Ham_RADIO@... wrote:

> __________________________________________________________
> Re: DVAP and the DVRPTR boards
> Posted by: "John D. Hays" john@... k7ve
> Date: Wed Jun 5, 2013 4:36 pm ((PDT))
>
> DVAP - small "Dongle" type 2m or 70cm radio that you plug into a
> computer, it transmits at about 10mw and is the popular choice for "in
> house" access to the D-STAR digital voice network.
> http://www.dvapdongle.com/DV_Access_Point_Dongle/Home.html
>
> DVRPTR V1 - A GMSK modem based on DSP that goes between a computer,
> attached by USB, and an existing 2-way radio (9600 bps packet ready)
> to give access to the D-STAR digital vocie network -
> http://www.dvrptr.net/
>
> STARBoard - A GMSK modem based on a dedicated modem chip that goes
> between a computer, attached by USB, and an existing 2-way radio (9600
> bps packet ready) to give access to the D-STAR digital vocie network
> - http://moencomm.com/
>
> UDR56k-4 - A new digital radio, 70cm/25 watts, built in DSP modems for
> D-STAR Digital Voice, D-STAR Digital Data (56kbps+ Ethernet over
> radio), packet radio from 9600 bps - 56kbps +, and more. Built in
> computer to run the DSP modems, protocol stacks, and applications on a
> Linux operating system (Debian / ARM). Open source for experimenters.
> Gateway or end user radio. http://nwdigitalradio.com (Discount on
> pre-orders until the 15th).
> [I am a member of the team creating this radio.]
>
> ------------------------------
> John D. Hays
> K7VE
> PO Box 1223, Edmonds, WA 98020-1223
> <http://k7ve.org/blog> <http://twitter.com/#!/john_hays>
> <http://www.facebook.com/john.d.hays>
>

Remember that those things are anything but low cost, closed source, and
your not even legally permitted to reverse engineer the protocol! (Not
that it stops some...)

Not great for "Amateur" radio, turning us into "appliance users" nothing
else.

There are better and truly "open" audio codec's about, FreeDV being one.
http://freedv.org/tiki-index.php

Scroll down to the Links seciton, for a lot more info.

73.

Dave G0WBX.


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