D-STAR23cm@groups.io

W4ART Arthur Feller

Moderators Note: NXDN was designed for business communications not ham radio consequently the radios do not have VFOs and are not frequency agile requiring channel programming in advance. Radios & repeaters can do dual-mode FM & Digital Voice on VHF & UHF bands only. NXDN Digital Voice is 6.25 KHz bandwidth using FDMA modulation. While NXDN has the positive performance characteristics of digital voice the radios do not have ham callsign identification. Icom sells networking capability, but it is designed for a closed business network not an open ham oriented network like D-STAR. APCO P25 has many of the same deficiencies when used in ham radio as well.

Hi!

Has anyone on the list explored the NXDN common air interface?  Uses the AMBE-2 vocoder and is, otherwise, an open system.

ICOM and Kenwood are producing equipment now.

Looks like it might be more robust than D-STAR, though it's voice or data and not both at the same time.

See: 

Thanks!!

73, art.....
W4ART  Arlington VA

W4ART Arthur Feller

#203

Moderator's Note: There is a small group in a rural area of central Illinois that are also using Icom IDAS NXDN radios & a repeater. It works OK for them. Of course NXDN systems don't integrate into the D-STAR network, but I suppose they could be connected to IRLP or Echolink or maybe the Asterisk technology.

Hi, Moderator!

Thanks for the note.

Some amateur NXDN systems are now operating, according to a ham I met at the Radio Club of America meeting this last weekend.  (100th anniversary!!)  Been trying to learn more.

Although D-STAR is ham oriented, the protocol is very weak in the presence of multi-path propagation.  Diversity receivers fix the problem nicely.  But, diversity receivers are expensive and not built into repeaters or handheld radios.  What to do??

Given that both ICOM and Kenwood designed this system jointly and some hams already use it, it seems that NXDN might be worth a look.  I don't know.  Lots to learn!!

Anybody have knowledge or experience to add?

Thanks!!

73, art.....
W4ART  Arlington VA

adkins.james@gmail.com

#204

Moderator's Note: MOTOTRBO like NXDN is designed for business communications. MOTOTRBO like NXDN & P25 has no callsign ID of radios and radios are channelized & not easily frequency agile. 
Icom has an interesting white paper comparing NXDN FDMA to MOTOTRBO TDMA at: www.idas625.com/Information_Paper_FDMA_TDMA.pdf 

This group is not meant to be a discussion of whether D-STAR is better or worse than P25 or MOTOTRBO or NXDN, but it can be helpful to understand the capabilities of other commercial digital voice technologies since hams often consider using them instead of D-STAR. 

Mototrbo is a much better protocol than NXDN.  Audio is much better and it is 2 time slot TDMA, allowing digital data and digital voice on the same frequency simultaneously or two digital voice conversations.  It is also open protocol, and thus legal on the ham bands.  It is set ip for RoIP out of the box, no external equipment needed.  Future expansion to 4 time slot TDMA is coming soon, as is mixed mode repeaters allowing analog users to use it as well as digital, similar to P25, but at a much lower cost.  The fact that D* doesn't do mixed mode or multiple time slots is a big disadvantage in my opinion.  Hams are using trbo equipment like crazy on the west coast for wide area linked systems.  The cost of a mototrbo repeater is only about $2400, too, about the same as a single D* repeater and controller.

I'm not sure that their data throughput can live up to the 128k of D*, though.

Sent via BlackBerry by AT&T

Show quoted text

-----Original Message-----
From: W4ART Arthur Feller <afeller@...>
Date: Tue, 24 Nov 2009 23:20:48 
To: <D-STAR_23cm@...>
Subject: Re: [D-STAR_23cm] NXDN

Moderator's Note: There is a small group in a rural area of central Illinois that are also using Icom IDAS NXDN radios & a repeater. It works OK for them. Of course NXDN systems don't integrate into the D-STAR network, but I suppose they could be connected to IRLP or Echolink or maybe the Asterisk technology.

Hi, Moderator!

Thanks for the note.

Some amateur NXDN systems are now operating, according to a ham I met at the Radio Club of America meeting this last weekend.  (100th anniversary!!)  Been trying to learn more.

Although D-STAR is ham oriented, the protocol is very weak in the presence of multi-path propagation.  Diversity receivers fix the problem nicely.  But, diversity receivers are expensive and not built into repeaters or handheld radios.  What to do??

Given that both ICOM and Kenwood designed this system jointly and some hams already use it, it seems that NXDN might be worth a look.  I don't know.  Lots to learn!!

Anybody have knowledge or experience to add?

Thanks!!

73, art.....
W4ART  Arlington VA

#214

Gentleman although this is not a topic of this group, the info regarding Mototrbo and Nxdn are not accurate. Nexedge (the Kenwood version of nxdn) has excellent voice quality and it is far more advanced.It supports mixed mode simultaneously (and not one at a time), it uses trunking with up to 48 site connectivity. A big difference also is that Mototrbo can only support 2 concurrent channels no matter how many repeaters you connect via Ip. Nexedge supports up to 30 concurrent channels per single site (trunking mode) and can connect up to 48 sites to one big network. TDMA (mototrbo) uses 12.5 KHz, NXDN uses 6.5 KHz. TDMA needs time synchronizing so shorter distance between user and repeater. There are many more details that I can explain if there is interest but using off list mail.

Regards Manos SV1IW

Show quoted text

--- In D-STAR_23cm@..., adkins.james@... wrote:

Moderator's Note: MOTOTRBO like NXDN is designed for business communications. MOTOTRBO like NXDN & P25 has no callsign ID of radios and radios are channelized & not easily frequency agile.
Icom has an interesting white paper comparing NXDN FDMA to MOTOTRBO TDMA at: www.idas625.com/Information_Paper_FDMA_TDMA.pdf

This group is not meant to be a discussion of whether D-STAR is better or worse than P25 or MOTOTRBO or NXDN, but it can be helpful to understand the capabilities of other commercial digital voice technologies since hams often consider using them instead of D-STAR.

Mototrbo is a much better protocol than NXDN.  Audio is much better and it is 2 time slot TDMA, allowing digital data and digital voice on the same frequency simultaneously or two digital voice conversations.  It is also open protocol, and thus legal on the ham bands.  It is set ip for RoIP out of the box, no external equipment needed.  Future expansion to 4 time slot TDMA is coming soon, as is mixed mode repeaters allowing analog users to use it as well as digital, similar to P25, but at a much lower cost.  The fact that D* doesn't do mixed mode or multiple time slots is a big disadvantage in my opinion.  Hams are using trbo equipment like crazy on the west coast for wide area linked systems.  The cost of a mototrbo repeater is only about $2400, too, about the same as a single D* repeater and controller.

I'm not sure that their data throughput can live up to the 128k of D*, though.

Sent via BlackBerry by AT&T

-----Original Message-----
From: W4ART Arthur Feller <afeller@...>
Date: Tue, 24 Nov 2009 23:20:48
To: <D-STAR_23cm@...>
Subject: Re: [D-STAR_23cm] NXDN

Moderator's Note: There is a small group in a rural area of central Illinois that are also using Icom IDAS NXDN radios & a repeater. It works OK for them. Of course NXDN systems don't integrate into the D-STAR network, but I suppose they could be connected to IRLP or Echolink or maybe the Asterisk technology.

Hi, Moderator!

Thanks for the note.

Some amateur NXDN systems are now operating, according to a ham I met at the Radio Club of America meeting this last weekend.  (100th anniversary!!)  Been trying to learn more.

Although D-STAR is ham oriented, the protocol is very weak in the presence of multi-path propagation.  Diversity receivers fix the problem nicely.  But, diversity receivers are expensive and not built into repeaters or handheld radios.  What to do??

Given that both ICOM and Kenwood designed this system jointly and some hams already use it, it seems that NXDN might be worth a look.  I don't know.  Lots to learn!!

Anybody have knowledge or experience to add?

Thanks!!

73, art.....
W4ART  Arlington VA

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