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New Updates on Site

John Hays <john@...>
 

See new information on http://nwdigitalradio.com

Sent from my iPhone

Mark L Friedlander <marklfriedlander@...>
 

I understand there have been some changes to the specs since we preordered so I'd like to clarify the details on what I'm buying.

I understood that originally, I would have been able to use the UDR56K for 9600 and 56k packet without adding a TNC. As indicated by the name change and earlier posts, it appears that 56k packet is no longer included. Is that correct? What about 9600 packet. Will the new version UDRX-440 be capable of 9600 packet without an additional TNC?

Thanks,
Mark KV4I



On Mon, Dec 23, 2013 at 4:50 PM, John Hays <john@...> wrote:
 

See new information on http://nwdigitalradio.com

Sent from my iPhone


"John D. Hays" <john@...>
 

Hi Mark,

The in-built modem capability allows different speeds and modulation under software definition.

9600-bps packet, without the need for an external TNC, will be supported right out of the box.  

The name change reflects that the top speed is yet TBD, but will be greater than 56kbps.  

The faster modems will roll out as software selectable updates as we prove them out in the lab.  

The 56kbps speed could be supported, but due to the lack of a significant installed base, we are dedicating engineering resources to leap-frogging that particular rate, in favor of a higher delivered speed.

By design, the UDRX-440 will support modems and protocols (e.g. soft TNC) within the radio itself and should not require an external modem for any supported speed and protocol of the radio itself.  (One might attach an additional TNC or Node Adapter and radio to provide bridging capability to another band or mode [e.g. a 1200 baud 2m port], but this is not required for general operation.)



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




On Mon, Dec 23, 2013 at 2:18 PM, Mark L Friedlander <marklfriedlander@...m> wrote:
 

I understand there have been some changes to the specs since we preordered so I'd like to clarify the details on what I'm buying.

I understood that originally, I would have been able to use the UDR56K for 9600 and 56k packet without adding a TNC. As indicated by the name change and earlier posts, it appears that 56k packet is no longer included. Is that correct? What about 9600 packet. Will the new version UDRX-440 be capable of 9600 packet without an additional TNC?

Thanks,
Mark KV4I

Mark L Friedlander <marklfriedlander@...>
 

Thank you, John. I understand and agree with the idea that 56kbps speed could be supported, but due to the lack of a significant installed base, you are dedicating engineering resources to leap-frogging that particular rate, in favor of a higher delivered speed. I think  faster modems rolling out as software selectable updates is particularly slick. I like that. In the meantime, I can use the UDRX440 for a 9600 packet node for less than the cost of a 440 radio and TNC.

73 Mark KV4I




On Mon, Dec 23, 2013 at 6:02 PM, John D. Hays <john@...> wrote:
 

Hi Mark,

The in-built modem capability allows different speeds and modulation under software definition.

9600-bps packet, without the need for an external TNC, will be supported right out of the box.  

The name change reflects that the top speed is yet TBD, but will be greater than 56kbps.  

The faster modems will roll out as software selectable updates as we prove them out in the lab.  

The 56kbps speed could be supported, but due to the lack of a significant installed base, we are dedicating engineering resources to leap-frogging that particular rate, in favor of a higher delivered speed.

By design, the UDRX-440 will support modems and protocols (e.g. soft TNC) within the radio itself and should not require an external modem for any supported speed and protocol of the radio itself.  (One might attach an additional TNC or Node Adapter and radio to provide bridging capability to another band or mode [e.g. a 1200 baud 2m port], but this is not required for general operation.)



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




On Mon, Dec 23, 2013 at 2:18 PM, Mark L Friedlander <marklfriedlander@...m> wrote:
 

I understand there have been some changes to the specs since we preordered so I'd like to clarify the details on what I'm buying.

I understood that originally, I would have been able to use the UDR56K for 9600 and 56k packet without adding a TNC. As indicated by the name change and earlier posts, it appears that 56k packet is no longer included. Is that correct? What about 9600 packet. Will the new version UDRX-440 be capable of 9600 packet without an additional TNC?

Thanks,
Mark KV4I


"Michael E. Fox - N6MEF" <n6mef@...>
 

It seems like the target keeps changing.  “If you don’t know where you’re going, any road will take you there.”

 

Even if a higher speed is possible, it may not be deployable in many locations due to path issues.  Those familiar with deployment of WiFi or digital LMR technologies like P25, DMR, etc. know that the individual circumstances of each path dictate which encoding schemes work and which are just too iffy to be used beyond a certain bit rate.  The denser the constellation, the more perfect the signal needs to be.  Otherwise, what would not be a decoding error at a lower rate becomes an unbearable error level (beyond the ability of FEC to correct) at higher levels.  You can see this on protocol-specific analyzers as the error rate gets higher until FEC breaks down.  To be deployable in multiple environments, a variety of encodings/speeds and channel widths is needed.

 

So, if you start out at only higher speeds, you may end up with something fast in the lab that is not deployable except in limited situations, like path-perfect, mountain-top to mountain-top situations.  And even with mountain-top to mountain-top, if the link is long, you may need to drop back on the speed to lower the error rate Or, maybe you don’t have the right size channel available so you may need to drop back.  (Mountain-top to mountain-top means you’re taking up that channel over a much wider geography and you need to make room for everyone.)  For the price, the thing needs to be able to be deployed in a variety of different scenarios.  At least make sure that we can select various rates/encoding schemes and channel widths.

 

Also, I hope whatever you do includes an analyzer that shows the constellation, decoding error rate, modulation quality, etc.  This will be important for determining the link quality at install time or when diagnosing problems.  Otherwise, even if it works, we’re just sitting there with our fingers crossed, not knowing how close we are to it not working.  Examples of the functionality would be something like the analyzer for P25, DMR, etc. in the Anritsu LMR Master or the Aeroflex analyzer line (several models).  They all pretty much show the same information.

 

I really, REALLY want this product to work.  Hopefully I’m not mentioning anything that the designers/developers don’t already know and are working on.  But I don’t see these real-world issues addressed in the discussion.  So it leads me to wonder…. 

 

Michael

N6MEF

  

bhhoyer@...
 

Hi Michael,


Some good points. I will post a full reply after the Holidays


Bryan

bhhoyer@...
 

Hi Michael, thanks for your input. Here's a point by point response.


# It seems like the target keeps changing.


Quoting from the Press Release at Hamvention 2012:


"The radio will support data rates from 4800-56K+ bps with selectable modulation methods including GMSK, FSK, and 4FSK. The UDR56K will operate in the 70cm band (420-450 mHz.) at up to 25 watts."


As of today we have reduced the band to 430-450, due to availability of SAW filters and increased the upper limit to in excess of 100k.


As far as dropping legacy 56k support. We would rather spend engineering effort on a modern FEC modem.


We are still on target.


# Even if a higher speed is possible, it may not be deployable in many locations due to path issues. 


We are releasing 9600 packet and 4800 D-STAR for full compatibility with the installed base.


Past that, you are absolutely right about the difficulties at higher speeds, so let me clarify our position.


Although lab work is required for verification prior to deployment, the real world is all that matters. We are working with some distinguished modem designers who have decades of experience in this area.


As we announced at DCC in November:


The UDRX will ship with a "Channel Sounder" which will allow all of our users to explore the field performance of candidate modems after they are released (all modems are open-source software plug-ins). I expect many hams will provide the data from mobile stations reporting back to an Internet-connected station where the data will be available on our website.


This data collection and optimization period will last for the better part of the year and result in a short list of modems/rates for different conditions. A negotiation protocol can be added later to establish the fastest reliable connection for a given situation including fall-back as you suggest.


# Also, I hope whatever you do includes an analyzer that shows …


RSSI and BER are built-in as are forward/reflected power. In the process of testing our receiver, it became necessary to inspect the data at various points and display the results graphically. We currently have a crude file based tool that allows us to collect a sample and post-process it using open source tools for things like constellation


The next step will be to connect to the receiver over a socket and display the results using something like WebGL. We will provide the socket but the rest is a substantial software task and we expect some talented Ham will pick this up. I have spoken to a couple of candidates already, but this is not a deliverable item for NW Digital Radio at this time.


All of our software is open-source so anyone may take our internal tools and build on them. If you have a strong math background and the requisite lab equipment, you can design your own modem using our base 9600 FSK/4800 GMSK as a reference.


# I really, REALLY want this to work


Nobody wants this to work more than I do. Except maybe my wife and my increasingly nervous banker.


Onward,

Bryan K7UDR