Idas questions - probably simple ones

[486dx4]

Hi -

I have read the brochures, etc on Icom's idas system (and Kenwood Nexedge) - the NXDN equipment.and I had some questions about it that some may know - probably simple stuff. All of the questions deal with conventional operation only.

- How does mixed node actually work with NXDN? The brochures talk about allowing analog radios to talk to idas radios which I kind of get but what does the detection of the analog or digital carrier? Is it the repeater or do the idas mobiles/portables do this as well in simplex?

- For mixed mode can the idas repeater go both ways? What I mean is if the idas radios are in with other analog radios on a conventional system and the idas radios are all digital can they communicate with the analog equipment on transmit and receive going through the idas repeater. After writing this maybe the 1st and 2nd questios are the same perhaps.

- For the Icom Idas repeater on digital only (no analog). How do you set up two 6.25 Khz channels like the brochures describe? Do you need a repeater with an additional RF module (channel module?) to make that happen? Or is the base repeater enough for doing this?

 

[WayneH]

- How does mixed node actually work with NXDN? The brochures talk about allowing analog radios to talk to idas radios which I kind of get but what does the detection of the analog or digital carrier? Is it the repeater or do the idas mobiles/portables do this as well in simplex?

When properly programmed the field radio can determine whether to receive both or one or the other. The repeater, when set up for mixed mode, can determine on reception which mode to repeat also.

- For mixed mode can the idas repeater go both ways?

The repeater is just that, it repeats what it receives. The repeater cannot receive digital and re-transmit analog if that's what you were asking. It will do one or the other when programmed for it.

- For the Icom Idas repeater on digital only (no analog). How do you set up two 6.25 Khz channels like the brochures describe? Do you need a repeater with an additional RF module (channel module?) to make that happen? Or is the base repeater enough for doing this?

The repeater chassis has two spaces for two RF modules (or essentially two repeaters). You will still have two connections to contend with for each module.

 

[486dx4]

Thanks Wayne for the info -

That is what I thought - the repeater cannot take digital and put it back to analog for the older radios in the system so for everything to really work (everyone can talk to everyone else regardless of what equipment they have) you would need to have everything set to analog on transmit and receive until the older equipment goes away then you can flip over to digital. Otherwise if the idas portables are programmed as digital for transmit the analog portables won't hear anything so to speak - you would hear the "hash" of the digital portables on FM when they talk..

As for the repeater the two channel (voice path) solution you would need two repeaters although you can for convenience put them in the same chassis to save space.

I am just looking at the comparisons between this system and Mototrbo. It seems that on both systems to have the backwards compatibility you have to be all analog until you get all digital equipment then you can change over to digital..

In terms of cost at this point from what I can see the idas portables/mobiles seem to be much less expensive than the mototrbo units. You also have reasonable access/cost of the software and upgrades, etc with icom. But on the repeater side it looks like to have the capability of two voice paths on a previous frequency where there was one path the repeater for idas maybe would be more expensive than a mototrbo repeater? - could be wrong on that if you really crunched the numbers. It seems though that the moto repeater does the 2 slot TDMA function out of the box with nothing added to buy and no need for another duplexer/circulator/amplifer (if licensed for the power)/antenna, etc. which is a factor. Again this is for conventional use so with trunking the debate changes on that I'd say.

This seems like another betamax vs. VHS or Blue Ray vs. HD-DVD situation where it is too early to see who if anyone will win out. I guess I'll stay tuned (as long as I can receive the signals of course).

Thanks again for the info on this though.

 

[stevelton]

I think I read a while back that mototrbo has only pass the FCC requirements for 12.5 narrowband. But it has be suggested that the FCC will some day make another switch to Narrow-Narrow band, 6.25.

While the mototrbo is 2 slots within one 12.5 channel, the FCC has not accepted that as 2 individual 6.25 channels, since the coordinators would have to allocate "2 6.25 channels" together, when the next switch to NNB happens. With REAL 6.25 systems like Icom, you will have an easier time getting better frequencies, because one 6.25 channel can be in this part of the band, and the other can be on a different part.

BTW, Icom is the only one with REAL 6.25. Kenwood is still working on theirs some, their NXDN is mainly 12.5 NB, not 6.25 NNB like Icom.

If you are shopping for your employer, send me a PM and we can talk some more details.

If your are just curious how it all works, then that is fine too.
Steven

 

[radiofan1]

BTW, Icom is the only one with REAL 6.25. Kenwood is still working on theirs some, their NXDN is mainly 12.5 NB, not 6.25 NNB like Icom.

Steven

WRONG. Try reading up on the NXDN Forum, specifically the CAI.

 

[486dx4]

Thanks Steven for the info. The interest is for curiousity right now but for where I volunteer our equipment is currently 12.5 Khz analog so for now there is compliance. Of course with a possible future mandate to NNB at 6.25 Khz (I have heard it called VNB for Very Narrow Band as well). I guess with mototrbo if a mandate does really happen for 6.25 Khz the equipment cannot be used at that point I guess. But then I have read that the FCC would for NNB/VNB allow it because it is "6.25 Khz efficiency equivalent" for 2 slot TDMA which is true I guess - but the frequency you are using is still 12.5 Khz wide. Of course what you read on the net sometimes may not be all that true.about these things. That's why I posted here to see what the experts had to say on this.

I have read too that Kenwood nexedge does 6.25 Khz as well like the icoms.

 

[RADIOGUY2002]

Huge and good post on this in Falcon Direct, pls read carefully. NXDN is a shared protocol between icom and kenwood (a few others as well). Think about that.

 

[486dx4]

Absolutely noted and its a good point... Having more than one manufacturer onboard (Icom, Kenwood, Rtiron) with this as well as Aeroflex to have test equipment for the protocol is a good thing to have.