Date   
Re: What's in a name?

Steve <yahoo-udr@...>
 

Incorporate the band, not the speed, into the model name.

On the current product, this might be:
UDR4 (70cm, 420-450MHz band)

Future products (we hope you folks will come up with) could be:
UDR2 (125cm, 222-225MHz band)
UDR9 (33cm, 902-928MHz band)

And FWIW: An Internet search will typically bring up a similar name no matter what you call it.

Re: What's in a name?

Mark L Friedlander <marklfriedlander@...>
 

UDR100 is already taken. Besides, why limit the speed in the name? As time progresses, faster models may become available. How about the HSUDR-1 for High Speed Universal Digital Radio version 1?


Mark KV4I



On Wed, Nov 20, 2013 at 11:43 AM, John D. Hays <john@...> wrote:
 

Have you ever thought about product names? It's kind of important.  A good name will identify a product in such a way that the observer is quick to understand the purpose of the product.

We have been thinking about the changes in the UDR56k-4 since it's first introduction.  At the time we had identified that the radio would be limited to a top data rate of 56 kbits.  This was in part due to the limitations of the modem/RF chip in our original design.  We have since changed our architecture into an I/Q Software Defined Modem (SDM) and will be delivering a modem that will likely exceed 100 kbits.

Steve, WA7PTM, contacted us and suggested we consider renaming the UDR56k-4 to reflect those changes and indicated we had a great resource --> the UniversalDigitalRadio Yahoo! Group.   We thought this was a great idea, thanks Steve.

We had been thinking about a model name change, but we thought Steve's suggestion was a great opportunity.

So, if you have a suggestion of what we should use for the name/model of the radio, here's your chance to change the destiny of all mankind :)

Please post your ideas.

Some guidelines:
  • We think it makes sense to keep UDR in the model number / name.
  • It should not infringe on any other trademark.
  • A Google search should not currently bring up an exact or very similar match
  • Keep it  short-ish.
  • Keep non-english meaning of the word(s) in mind (e.g. it shouldn't mean 'stinky eel' in Tongan)
  • Consider how it might relate to a family of products (e.g. a different band)

We will review your suggestions, and others developed in house. If there are several particularly good suggestions, we will create a survey where you can vote for your favorite.  

We reserve the right to use any or none of the suggestions.  

All suggestions become donated property of NW Digital Radio, without compensation. We will acknowledge the person or persons who came up with the chosen name.



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


What's in a name?

"John D. Hays" <john@...>
 

Have you ever thought about product names? It's kind of important.  A good name will identify a product in such a way that the observer is quick to understand the purpose of the product.

We have been thinking about the changes in the UDR56k-4 since it's first introduction.  At the time we had identified that the radio would be limited to a top data rate of 56 kbits.  This was in part due to the limitations of the modem/RF chip in our original design.  We have since changed our architecture into an I/Q Software Defined Modem (SDM) and will be delivering a modem that will likely exceed 100 kbits.

Steve, WA7PTM, contacted us and suggested we consider renaming the UDR56k-4 to reflect those changes and indicated we had a great resource --> the UniversalDigitalRadio Yahoo! Group.   We thought this was a great idea, thanks Steve.

We had been thinking about a model name change, but we thought Steve's suggestion was a great opportunity.

So, if you have a suggestion of what we should use for the name/model of the radio, here's your chance to change the destiny of all mankind :)

Please post your ideas.

Some guidelines:
  • We think it makes sense to keep UDR in the model number / name.
  • It should not infringe on any other trademark.
  • A Google search should not currently bring up an exact or very similar match
  • Keep it  short-ish.
  • Keep non-english meaning of the word(s) in mind (e.g. it shouldn't mean 'stinky eel' in Tongan)
  • Consider how it might relate to a family of products (e.g. a different band)

We will review your suggestions, and others developed in house. If there are several particularly good suggestions, we will create a survey where you can vote for your favorite.  

We reserve the right to use any or none of the suggestions.  

All suggestions become donated property of NW Digital Radio, without compensation. We will acknowledge the person or persons who came up with the chosen name.



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

New Update on NW Digital Radio Blog

john@...
 

http://nwdigitalradio.com/udr-progress-report

Re: Any updates on the release?

bhhoyer@...
 

Thanks Matthew,


I'll post an update later today. 



---In UniversalDigitalRadio@..., <daywalker_blade_2004@...> wrote:

No; "patience grasshopper". Give them time to work things out to the best advantage of all users.

Matthew Pitts
N8OHU



From: "dperv27@..." <dperv27@...>
To: UniversalDigitalRadio@...
Sent: Friday, November 8, 2013 6:24 PM
Subject: [UniversalDigitalRadio] Any updates on the release?

 
Any new updates on the release date?  The website doesn't have any new updates.


Re: Any updates on the release?

Matthew Pitts <daywalker_blade_2004@...>
 

No; "patience grasshopper". Give them time to work things out to the best advantage of all users.

Matthew Pitts
N8OHU



From: "dperv27@..."
To: UniversalDigitalRadio@...
Sent: Friday, November 8, 2013 6:24 PM
Subject: [UniversalDigitalRadio] Any updates on the release?

 
Any new updates on the release date?  The website doesn't have any new updates.


Re: Update on the UDR transceiver

"n0cf (Chris Conklin)" <n0cf@...>
 

Here-here!

Patience is usually/sometimes/? a virtue

 

From: UniversalDigitalRadio@... [mailto:UniversalDigitalRadio@...] On Behalf Of john@...
Sent: Wednesday, November 13, 2013 6:33 PM
To: UniversalDigitalRadio@...
Subject: [UniversalDigitalRadio] RE: Update on the UDR transceiver

 

 Many of our future customers have told us that they prefer we "do it right" before release.

Re: Update on the UDR transceiver

john@...
 

An announcement was made at DCC this year http://nwdigitalradio.com/breaking-the-100kbit-barrier


Here's a quick status:


We continue to code.  The main issue over late summer was difficulty with implementing the SOC (CPU) to our ADC/DAC chip.  Support for small design/manufacturing shops from the chip foundries leaves much to be desired and documentation is often incomplete.  This requires a lot of trial and error during driver work.   


The good news is that we seem to have had a good breakthrough on the driver and now the software defined modems can start exercising the RF section of the radio.  Much of the protocol / application work has been running for many months -- so end-to-end test and integration can proceed.

Our re-architecture of the radio / modem section made the implementation more complex (and extended work) but will lead to a better end product.

We will release updated schedules once we are able to complete integration and test.


We appreciate the support and growing interest.  Many of our future customers have told us that they prefer we "do it right" before release.



---In universaldigitalradio@..., <dperv27@...> wrote:

I'm wondering if there is any update?

---In UniversalDigitalRadio@..., <jimns3k@...> wrote:

Any update on the UDR56K radio?

 

 

Jim

Re: Update on the UDR transceiver

dperv27@...
 

I'm wondering if there is any update?

Any updates on the release?

dperv27@...
 

Any new updates on the release date?  The website doesn't have any new updates.

Re: Serval "Mesh Extender" (WiFi to UHF packet)

VE7CBH <ve7cbh@...>
 

What is a WD unit?
 

------ Original Message ------
Sent: 26/09/2013 7:31:38 AM
Subject: [UniversalDigitalRadio] RE: Serval &quot;Mesh Extender&quot; (WiFi to UHF packet)


Got all the stuff together to start setting up my MESH testing.  Am the only one in the area so far, but once I get my WD unit I hope to link to the system.  

Tom de VE7GDA/BH  



---In universaldigitalradio@..., wrote:

I for one am patiently waiting for my second WIFI modem so I can get going.  All is in place, so will be watching this thread closely.  Nobody near me yet, but hope to get some club members working.   



--- In universaldigitalradio@..., wrote:

I'm a bit of a fan of mesh networking devices and we are now introducing the Village Telco "Mesh Potato" wireless telephony/data device to our county EMA.

That said, I ran across this on the FreedomBox mailing list. The Serval Project is a cousin to the Mesh Potato and uses open software to connect Android devices without the commercial infrastructure. The note below relates to the addition of 900 MHz UHF devices as range extenders for the 2.4 GHz mesh network. This is all Part 15 but I found the mix of 2.4 GHz WiFi and UHF to be interesting and something that might be relevant to this group. The bottom line of the note is an appeal for funding but there's enough meat to make it interesting.

FreedomBox, FYI, is a personal server development project intended to provide privacy.

Steve KB1TCE

Message: 3
Date: Tue, 9 Jul 2013 04:37:04 +0930
From: Paul Gardner-Stephen <paul@...>
To: freedombox-discuss <freedombox-discuss@...>
Subject: [Freedombox-discuss] Crowd-funding the Serval Mesh Extender
Message-ID:
Gjm87L5dgBD-jytV0hph_w@...>
Content-Type: text/plain; charset="iso-8859-1"

Hi All,

As some of you may already be aware we have been working on what we call the Mesh Extender at the Serval Project.

The Mesh Extender is a combined battery powered embedded Linux router and UHF packet radio running the Serval Mesh software (which is all GPL, see github.com/servalproject for the source).

It is intended for mobile and truly ad-hoc deployment where the end user just turns it on and uses it.

The idea is that it uses the UHF packet radio to mesh over greater
distances than is possible with Wi-Fi, the trade-off being lower bandwidth.

In general, we find that the UHF packet radio has a range of about 10x that of Wi-Fi when deployed indoors with omni-directional antennae. This means it has a range of about a block in a suburban or urban setting compared with Wi-Fi's range of about one house or apartment.

For example testing it in Boston recently we had coverage over much of the MIT campus from a single Mesh Extender in my room at a nearby hotel:

http://servalpaul.blogspot.com/2013/05/range-testing-mesh-extenders-in-boston.html
http://servalpaul.blogspot.com/2013/05/range-testing-serval-mesh-extender-on.html
http://servalpaul.blogspot.com/2013/05/crossing-charles-river-by-mesh-extender.html

Extending the range in this way is a critical enabler for the adoption of mesh communications because it removes the need for skilled installation and lowers the required penetration rate from near 100% in a local area if using un-aimed Wi-Fi to below 1%:

http://servalpaul.blogspot.com/2013/05/urban-testing-of-mesh-extender-part-1.html
http://servalpaul.blogspot.com/2013/05/urban-testing-of-mesh-extender-part-2.html

Combined with the always-on end-to-end encryption of voice calls and text messages of the Serval Mesh we think that this device has the potential to play a significant role in enabling distributed, resilient and private communications for people in a wide variety of situations.

We also see that the close alignment of what the Freedom Box and Serval Project are trying to achieve means that any device like this that we create could easily be adapted to being both a Mesh Extender and Freedom Box by adapting the included software inventory.

The necessity of a portable and trivial to deploy enabler of mesh
communications, and the need for this to be completely open, has led us to the current point where we have setup a crowd funding campaign to develop this technology, taking it from the prototype stage and to develop an actual manufacturable product, and do further testing with our humanitarian partners.

This is the point that our campaign at igg.me/at/speakfreely will take us to if fully funded.

But to realise the full potential of this we not only need to make an
attractive manufacturable device, but also to improve the open-source
firmware of the packet radios we are using to support true "ad-hoc packet radio" within the complex regulatory requirements of the ISM 915MHz band, in particular the need to frequency hop which presents interesting technical challenges for a fully distributed mesh that does not rely on GPS timing for synchronisation.

Achieving "ad-hoc packet radio" will require us to not only meet our
current funding goal, but stretch it by a factor of two.

We are conscious that achieving this will require promoting the campaign far and wide, possibly wider than the Serval team can achieve alone.

Therefore it would be tremendously helpful if as many of you as are willing and able would assist us in spreading the word as far and wide as possible. We would love to get slash-dotted and reddited off the net. Repeatedly.

So please take a look at our campaign, use the words below if they are
helpful, and help us to get the word out, and ultimately let's make
effective and private long-range mesh communications not only possible, but practical and easy for the general public so that they can enjoy the resilient backup communications capability that they need to keep connected, no matter what disaster may befall them.

Thanks in advance,

Dr. Paul Gardner-Stephen
Founder, Serval Project.

---

Serval crowd-funding Mesh Extenders to make mesh & disaster telephony go the next mile http://igg.me/at/speakfreely

Serval Project has been working for three years with New Zealand Red Cross on free and open technology, called the Serval Mesh, which can keep mobile phones operating when mobile networks fail, such as during disasters. We now want to take this technology out of the lab and get it into peoples hands. Find out more at http://igg.me/at/speakfreely

Twitter: @ServalProject


Re: Serval "Mesh Extender" (WiFi to UHF packet)

thomas.wagner@...
 

Got all the stuff together to start setting up my MESH testing.  Am the only one in the area so far, but once I get my WD unit I hope to link to the system.  

Tom de VE7GDA/BH  



---In universaldigitalradio@..., <thomas.wagner@...> wrote:

I for one am patiently waiting for my second WIFI modem so I can get going.  All is in place, so will be watching this thread closely.  Nobody near me yet, but hope to get some club members working.   



--- In universaldigitalradio@..., <shansen@...> wrote:

I'm a bit of a fan of mesh networking devices and we are now introducing the Village Telco "Mesh Potato" wireless telephony/data device to our county EMA.

That said, I ran across this on the FreedomBox mailing list. The Serval Project is a cousin to the Mesh Potato and uses open software to connect Android devices without the commercial infrastructure. The note below relates to the addition of 900 MHz UHF devices as range extenders for the 2.4 GHz mesh network. This is all Part 15 but I found the mix of 2.4 GHz WiFi and UHF to be interesting and something that might be relevant to this group. The bottom line of the note is an appeal for funding but there's enough meat to make it interesting.

FreedomBox, FYI, is a personal server development project intended to provide privacy.

Steve KB1TCE

Message: 3
Date: Tue, 9 Jul 2013 04:37:04 +0930
From: Paul Gardner-Stephen <paul@...>
To: freedombox-discuss <freedombox-discuss@...>
Subject: [Freedombox-discuss] Crowd-funding the Serval Mesh Extender
Message-ID:
<CA+_T8-AWOSZ1cUoFk1Vg+pVr9G1=Gjm87L5dgBD-jytV0hph_w@...>
Content-Type: text/plain; charset="iso-8859-1"

Hi All,

As some of you may already be aware we have been working on what we call the Mesh Extender at the Serval Project.

The Mesh Extender is a combined battery powered embedded Linux router and UHF packet radio running the Serval Mesh software (which is all GPL, see github.com/servalproject for the source).

It is intended for mobile and truly ad-hoc deployment where the end user just turns it on and uses it.

The idea is that it uses the UHF packet radio to mesh over greater
distances than is possible with Wi-Fi, the trade-off being lower bandwidth.

In general, we find that the UHF packet radio has a range of about 10x that of Wi-Fi when deployed indoors with omni-directional antennae. This means it has a range of about a block in a suburban or urban setting compared with Wi-Fi's range of about one house or apartment.

For example testing it in Boston recently we had coverage over much of the MIT campus from a single Mesh Extender in my room at a nearby hotel:

http://servalpaul.blogspot.com/2013/05/range-testing-mesh-extenders-in-boston.html
http://servalpaul.blogspot.com/2013/05/range-testing-serval-mesh-extender-on.html
http://servalpaul.blogspot.com/2013/05/crossing-charles-river-by-mesh-extender.html

Extending the range in this way is a critical enabler for the adoption of mesh communications because it removes the need for skilled installation and lowers the required penetration rate from near 100% in a local area if using un-aimed Wi-Fi to below 1%:

http://servalpaul.blogspot.com/2013/05/urban-testing-of-mesh-extender-part-1.html
http://servalpaul.blogspot.com/2013/05/urban-testing-of-mesh-extender-part-2.html

Combined with the always-on end-to-end encryption of voice calls and text messages of the Serval Mesh we think that this device has the potential to play a significant role in enabling distributed, resilient and private communications for people in a wide variety of situations.

We also see that the close alignment of what the Freedom Box and Serval Project are trying to achieve means that any device like this that we create could easily be adapted to being both a Mesh Extender and Freedom Box by adapting the included software inventory.

The necessity of a portable and trivial to deploy enabler of mesh
communications, and the need for this to be completely open, has led us to the current point where we have setup a crowd funding campaign to develop this technology, taking it from the prototype stage and to develop an actual manufacturable product, and do further testing with our humanitarian partners.

This is the point that our campaign at igg.me/at/speakfreely will take us to if fully funded.

But to realise the full potential of this we not only need to make an
attractive manufacturable device, but also to improve the open-source
firmware of the packet radios we are using to support true "ad-hoc packet radio" within the complex regulatory requirements of the ISM 915MHz band, in particular the need to frequency hop which presents interesting technical challenges for a fully distributed mesh that does not rely on GPS timing for synchronisation.

Achieving "ad-hoc packet radio" will require us to not only meet our
current funding goal, but stretch it by a factor of two.

We are conscious that achieving this will require promoting the campaign far and wide, possibly wider than the Serval team can achieve alone.

Therefore it would be tremendously helpful if as many of you as are willing and able would assist us in spreading the word as far and wide as possible. We would love to get slash-dotted and reddited off the net. Repeatedly.

So please take a look at our campaign, use the words below if they are
helpful, and help us to get the word out, and ultimately let's make
effective and private long-range mesh communications not only possible, but practical and easy for the general public so that they can enjoy the resilient backup communications capability that they need to keep connected, no matter what disaster may befall them.

Thanks in advance,

Dr. Paul Gardner-Stephen
Founder, Serval Project.

---

Serval crowd-funding Mesh Extenders to make mesh & disaster telephony go the next mile http://igg.me/at/speakfreely

Serval Project has been working for three years with New Zealand Red Cross on free and open technology, called the Serval Mesh, which can keep mobile phones operating when mobile networks fail, such as during disasters. We now want to take this technology out of the lab and get it into peoples hands. Find out more at http://igg.me/at/speakfreely

Twitter: @ServalProject

Update on the UDR transceiver

jimns3k@...
 

Any update on the UDR56K radio?

 

 

Jim

Re: NW Digital Radio Discusses Higher Data Speed Plans

PE1RDW <pe1rdw@...>
 

good news, hope it works out as speed can never be to low

73 Andre PE1RDW
op 25-09-13 21:36, john@... schreef:

NW Digital Radio Discusses Higher Data Speed Plans

john@...
 

ARRL/TAPR DCC Forum Schedule, Banquet Speaker & Sunday Seminar Announced

Mark Thompson <wb9qzb_groups@...>
 

 
2013 ARRL/TAPR DCC (Digital Communication Conference)
 
Friday, 9/20 - Sunday, 9/22
 
Cedarbrook Lodge, Seattle, WA
 
 
Preliminary DCC Technical & Introductory Forums Schedule
On-Line at link below & attached:
 
 
ARRL/TAPR DCC Seattle Saturday Evening Banquet Speaker will be: 
Tom Van Baak
Presenting
“Passion and Precision: Adventures of a Time Nut”
 
 
ARRL/TAPR DCC Seattle Sunday Morning Seminar will be 
Conducted by Ron Frohne, KL7NA 
Presenting "Android Programming Tutorial"
 
 
On-line DCC Registration at:
 
The Early Bird Discount for DCC Pre-Registration has been extended to midnight Friday, September 13.
Walk-ins will be welcome throughout the DCC, but the Early Bird Discount will no longer be applicable




Re: Serval "Mesh Extender" (WiFi to UHF packet)

thomas.wagner@...
 

I for one am patiently waiting for my second WIFI modem so I can get going.  All is in place, so will be watching this thread closely.  Nobody near me yet, but hope to get some club members working.   



--- In universaldigitalradio@..., <shansen@...> wrote:

I'm a bit of a fan of mesh networking devices and we are now introducing the Village Telco "Mesh Potato" wireless telephony/data device to our county EMA.

That said, I ran across this on the FreedomBox mailing list. The Serval Project is a cousin to the Mesh Potato and uses open software to connect Android devices without the commercial infrastructure. The note below relates to the addition of 900 MHz UHF devices as range extenders for the 2.4 GHz mesh network. This is all Part 15 but I found the mix of 2.4 GHz WiFi and UHF to be interesting and something that might be relevant to this group. The bottom line of the note is an appeal for funding but there's enough meat to make it interesting.

FreedomBox, FYI, is a personal server development project intended to provide privacy.

Steve KB1TCE

Message: 3
Date: Tue, 9 Jul 2013 04:37:04 +0930
From: Paul Gardner-Stephen <paul@...>
To: freedombox-discuss <freedombox-discuss@...>
Subject: [Freedombox-discuss] Crowd-funding the Serval Mesh Extender
Message-ID:
<CA+_T8-AWOSZ1cUoFk1Vg+pVr9G1=Gjm87L5dgBD-jytV0hph_w@...>
Content-Type: text/plain; charset="iso-8859-1"

Hi All,

As some of you may already be aware we have been working on what we call the Mesh Extender at the Serval Project.

The Mesh Extender is a combined battery powered embedded Linux router and UHF packet radio running the Serval Mesh software (which is all GPL, see github.com/servalproject for the source).

It is intended for mobile and truly ad-hoc deployment where the end user just turns it on and uses it.

The idea is that it uses the UHF packet radio to mesh over greater
distances than is possible with Wi-Fi, the trade-off being lower bandwidth.

In general, we find that the UHF packet radio has a range of about 10x that of Wi-Fi when deployed indoors with omni-directional antennae. This means it has a range of about a block in a suburban or urban setting compared with Wi-Fi's range of about one house or apartment.

For example testing it in Boston recently we had coverage over much of the MIT campus from a single Mesh Extender in my room at a nearby hotel:

http://servalpaul.blogspot.com/2013/05/range-testing-mesh-extenders-in-boston.html
http://servalpaul.blogspot.com/2013/05/range-testing-serval-mesh-extender-on.html
http://servalpaul.blogspot.com/2013/05/crossing-charles-river-by-mesh-extender.html

Extending the range in this way is a critical enabler for the adoption of mesh communications because it removes the need for skilled installation and lowers the required penetration rate from near 100% in a local area if using un-aimed Wi-Fi to below 1%:

http://servalpaul.blogspot.com/2013/05/urban-testing-of-mesh-extender-part-1.html
http://servalpaul.blogspot.com/2013/05/urban-testing-of-mesh-extender-part-2.html

Combined with the always-on end-to-end encryption of voice calls and text messages of the Serval Mesh we think that this device has the potential to play a significant role in enabling distributed, resilient and private communications for people in a wide variety of situations.

We also see that the close alignment of what the Freedom Box and Serval Project are trying to achieve means that any device like this that we create could easily be adapted to being both a Mesh Extender and Freedom Box by adapting the included software inventory.

The necessity of a portable and trivial to deploy enabler of mesh
communications, and the need for this to be completely open, has led us to the current point where we have setup a crowd funding campaign to develop this technology, taking it from the prototype stage and to develop an actual manufacturable product, and do further testing with our humanitarian partners.

This is the point that our campaign at igg.me/at/speakfreely will take us to if fully funded.

But to realise the full potential of this we not only need to make an
attractive manufacturable device, but also to improve the open-source
firmware of the packet radios we are using to support true "ad-hoc packet radio" within the complex regulatory requirements of the ISM 915MHz band, in particular the need to frequency hop which presents interesting technical challenges for a fully distributed mesh that does not rely on GPS timing for synchronisation.

Achieving "ad-hoc packet radio" will require us to not only meet our
current funding goal, but stretch it by a factor of two.

We are conscious that achieving this will require promoting the campaign far and wide, possibly wider than the Serval team can achieve alone.

Therefore it would be tremendously helpful if as many of you as are willing and able would assist us in spreading the word as far and wide as possible. We would love to get slash-dotted and reddited off the net. Repeatedly.

So please take a look at our campaign, use the words below if they are
helpful, and help us to get the word out, and ultimately let's make
effective and private long-range mesh communications not only possible, but practical and easy for the general public so that they can enjoy the resilient backup communications capability that they need to keep connected, no matter what disaster may befall them.

Thanks in advance,

Dr. Paul Gardner-Stephen
Founder, Serval Project.

---

Serval crowd-funding Mesh Extenders to make mesh & disaster telephony go the next mile http://igg.me/at/speakfreely

Serval Project has been working for three years with New Zealand Red Cross on free and open technology, called the Serval Mesh, which can keep mobile phones operating when mobile networks fail, such as during disasters. We now want to take this technology out of the lab and get it into peoples hands. Find out more at http://igg.me/at/speakfreely

Twitter: @ServalProject

Re: UDR56k-4 Sensitivity & BER

Bryan Hoyer <bhhoyer@...>
 

On the topic of Modulation

The data-sheet lists the modulation types implemented in the first release. These types support existing digital standards for compatibility.

The UDR uses an IQ XCVR and as such is capable of doing other modulation types, limited by the regs and the linearity of the PA. The modem is implemented in software and can be updated in the field.

We will release a full briefing on our software architecture at DCC.

Cheers,
Bryan K7UDR

On Aug 7, 2013, at 9:23 AM, "Michael E. Fox - N6MEF" <n6mef@...> wrote:

 


Around here in order to test anything I have to buy more radios and computers, there's no-one else to talk to.  That said, I'm interested in getting more radios :)

Absolutely!  I’m all for that!

Interesting, thanks for the info.  This was using Connected Mode AX.25 or TCP/IP over Disconnected Mode?

We tried both.  It doesn’t matter.  The errored packet still needs to be retransmitted, regardless of whether it is AX.25 or TCP/IP that makes the decision.




Sure.   This is why i thought quoting the sensitivity for a BER of 10^-3 was a bit odd.  I assume that post-correction residual BER figures for modems with FEC would be used in the sensitivity figures when presented in the specs.

I believe that’s the case.  BER is certainly important and one needs to know where that break point is.  But it’s also important to understand that you can’t design a system to operate at the worst case 0% BER point.  The reason is that, with FEC, BER stays at 0% until the signal is so dirty that error correction can’t help it any more.  At that point, BER jumps up very quickly from 0% to 5% or more with just a dB or two of reduced C/I (Carrier to Interference ratio).  In other words, a 0% BER signal and a total unusable signal can be very, very close in C/I.  So, at the point where 0% BER is lost, you have little to no fade margin and your system will not be reliable.  In practice, the modulation fidelity value is monitored during such things as drive tests because it changes gradually as the signal quality gets worse.  That can help you determine the type of fade margin you need to build into your link budget.  Then, depending on the fade margin you need for your environment, you can then determine how much signal you need to stay away from the danger point.

 

On another point, I note that the UDR56K datasheet says the modulation types are FSK and GMSK.  I also know that the digital radio community is moving to PSK as a more reliable way to transmit higher bandwidths within the same spectrum.  I’m not a modulation engineer, but as I understand it, it’s evidently possible to switch more quickly and accurately between phases than it is to switch between frequencies, making for less bit/symbol errors.  I wonder if PSK, QPSK, etc. emission types are even allowed by our FCC Part 97 rules which govern ham radio.  Hmm… something to check.

 

Michael

N6MEF



Re: UDR56k-4 Sensitivity & BER

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


Around here in order to test anything I have to buy more radios and computers, there's no-one else to talk to.  That said, I'm interested in getting more radios :)

Absolutely!  I’m all for that!

Interesting, thanks for the info.  This was using Connected Mode AX.25 or TCP/IP over Disconnected Mode?

We tried both.  It doesn’t matter.  The errored packet still needs to be retransmitted, regardless of whether it is AX.25 or TCP/IP that makes the decision.




Sure.   This is why i thought quoting the sensitivity for a BER of 10^-3 was a bit odd.  I assume that post-correction residual BER figures for modems with FEC would be used in the sensitivity figures when presented in the specs.

I believe that’s the case.  BER is certainly important and one needs to know where that break point is.  But it’s also important to understand that you can’t design a system to operate at the worst case 0% BER point.  The reason is that, with FEC, BER stays at 0% until the signal is so dirty that error correction can’t help it any more.  At that point, BER jumps up very quickly from 0% to 5% or more with just a dB or two of reduced C/I (Carrier to Interference ratio).  In other words, a 0% BER signal and a total unusable signal can be very, very close in C/I.  So, at the point where 0% BER is lost, you have little to no fade margin and your system will not be reliable.  In practice, the modulation fidelity value is monitored during such things as drive tests because it changes gradually as the signal quality gets worse.  That can help you determine the type of fade margin you need to build into your link budget.  Then, depending on the fade margin you need for your environment, you can then determine how much signal you need to stay away from the danger point.

 

On another point, I note that the UDR56K datasheet says the modulation types are FSK and GMSK.  I also know that the digital radio community is moving to PSK as a more reliable way to transmit higher bandwidths within the same spectrum.  I’m not a modulation engineer, but as I understand it, it’s evidently possible to switch more quickly and accurately between phases than it is to switch between frequencies, making for less bit/symbol errors.  I wonder if PSK, QPSK, etc. emission types are even allowed by our FCC Part 97 rules which govern ham radio.  Hmm… something to check.

 

Michael

N6MEF

Re: UDR56k-4 Sensitivity & BER

Darren Long <darren.long@...>
 

On 06/08/13 17:12, Michael E. Fox - N6MEF wrote:
 
It’s even worse than that, especially in the real world.  A 20% loss rate will cause enough retransmits that a cascade failure will occur.  In other words, for those 20% that must be retransmitted, 20% of those will need to be retransmitted again, and so on.  If the link is more than a single user occasionally checking his BBS for short messages, the link becomes worthless pretty quickly.  For example, if there are a 3-4 systems on the frequency, even at only 128 byte packets, the channel becomes hopelessly clogged in very short order.

 

Even your 10^-4 example shows 10% loss of just 128 byte packets.  Again, way too high for anything more than a single user talking to a single station.  So, 20% loss is NOT manageable for AX.25.  Not even 10%.


Around here in order to test anything I have to buy more radios and computers, there's no-one else to talk to.  That said, I'm interested in getting more radios :)

When we first deployed our BBS network, we performed real testing with 9600 baud TNCs (no FEC).  We were getting somewhere in the range of 5% to 10% packet loss at 9600 baud and 0% packet loss at 1200 baud.  (This was not a lab test.  This was between real sites using real antennas.)  Two different TNC brands were used and, yes, deviation was verified to be per manufacturer’s specs.  As a result, even with the higher baud rate, the effective throughput was lower on 9600 than on 1200 baud. 

Interesting, thanks for the info.  This was using Connected Mode AX.25 or TCP/IP over Disconnected Mode?

 

To think that one could go higher in speed and not make things even worse, is just not facing reality.  In *real* environments, with more than just one user talking to one other station at a time, the BER must be much higher (10^-5 to 10^-6) in order for the channel to not rapidly degrade due to cascading retransmits.  For any *real* environment, FEC is going to be essential. 


Agreed.  John Ronan, EI7IG, and I have been experimenting with Delay Tolerant Networks over ham radio links.  There is convergence layer support for Connected Mode AX.25 (implemented by yours truly) in the DTN2 reference implementation and a Nack Oriented Reliable Multicast (NORM) protocol convergence layer too, both of which seem useful.  We've never tried NORM over UDP/IP/UI-Frames on AX.25 yet, but John's been dabbling with it on D-STAR DD.  NORM's packet level erasure codes work well, but with some modest link layer FEC too I should think it would work very well.

The standard level for measuring receiver sensitivity in digital radios is 10^-5 BER.  Anyone who is familiar with P25 or DMR testing will be familiar with modulation fidelity vs. BER.  Those systems have error correction.  The modulation fidelity (measure of how accurately the symbols are being received) can degrade quite severely while still maintaining a 0% BER.  Without forward error correction, these systems would be unusable in any real environment. 


Sure.   This is why i thought quoting the sensitivity for a BER of 10^-3 was a bit odd.  I assume that post-correction residual BER figures for modems with FEC would be used in the sensitivity figures when presented in the specs.

I’d love to deploy the UDR56 on our BBSs that share a common forwarding frequency.  But without FEC, there’s just no way.  The result would be predictably terrible.

I hope that any new modems developed for the UDR56k are prototyped in gnuradio and/or implemented in a userspace soundmodem so that I can experiment with them.  I don't currently have a car and I'm not too tempted to buy 2 UDR56k  units to run at home, but I was thinking of getting one in the hope that all my old AX.25 kit would interoperate with it and that I could use my USRP or a soundmodem to try out any fancy new waveforms. 

I wonder what the minimum tx power level achievable with the UDR56k is?


Cheers,

Darren, G0HWW