Any iDAS users out there?

[n1das]

Anybody out there using iDAS yet? If so, VHF? UHF? Conventional or trunked?

[N2DLX]

You already know me. All I have to add is.. IDAS GPS works like a charm..!

IDAS GPS Location

[n1das]

Originally Posted by N2DLX

You already know me. All I have to add is.. IDAS GPS works like a charm..!

IDAS GPS Location

I figured you'd chime in here. :-)

I've got some UHF Kenwood NEXEDGE portables working on a friend's UHF iDAS repeater (conventional) in 6.25k mode. He has some NEXEDGE portables and some Icom iDAS portables and mobiles. He is leaning more toward the Icom iDAS radios instead of Kenwood NEXEDGE radios.

I was mainly wondering who else on RR is playing around / using Icom iDAS or Kenwood NEXEDGE radios.

From some of the comments I've received from people who have listened to my audio samples at http://nxdn.mygmrs.com, I've had a few tell me they love the digital and I've had a few tell me they'd rather stick with analog, especially under weak signal conditions. From testing my friend and I have done, we've found one area where digital blows away analog any day. It's when you are hearing someone thru a repeater in analog and they are weak and scratchy into the repeater and you are also hearing the repeater very weak and scratchy. You're listening to a weak and noisy signal that's rebroadcasting the audio from a weak and noisy signal received by the repeater. It's essentially NOISE x 2, making it much harder to make out the person's audio. Digital totally 100% cleans this up, thanks to the benefit of forward error correction you get thru the (digital) repeater. The audio is still crystal clear instead of Noise x 2. We did this test on a UHF Icom FR6000 repeater. It does mixed analog/digital modes, so we were doing the analog vs. digital test test thru the same repeater under the same signal conditions. The only change was analog vs. digital modes during the test. I gotta figure out how to record an audio sample of this test!

NXDN Rocks, whether it's Kenwood NEXEDGE or Icom iDAS!

[pachanga22]

I did that the other day. Far enuff from repeater that keying one portable analog and waving the other around in the air, it would crack squelch but that's all. Went to digital and we could talk.

[N2DLX]

I'd love to mess around with the Kenwoods but I'm locked into Icom gear. I've compiled a ton of information about these radios, including the serial data. Do the Kenwoods have PC Control data sent over the serial port (similar to CAT on Ham radios)? It'd be great if Kenwood and Icom radios are compatible on that level -- all my data would then also pertain to Kenwood.

I heard a rumor Kenwood is working on 800 MHz NXDN radios. I wish Icom would expand their products outside of VHF and UHF.. it would benefit them immensely, especially with the new F9011 series where 800 MHz systems are a bigger chunk of the market.

[n1das]

The NXDN audio samples I've posted on Rich's site NXDN Information were done in simplex. The analog vs. digital difference under weak signal conditions is MUCH more dramatic when you are struggling to hear someone in analog that's just barely readable (i.e., very weak and scratchy) into a repeater and at the same time you are just barely hearing the repeater. Weak and scratchy on BOTH ends. Digital totally cleans it up!

[n1das]

Originally Posted by N2DLX

I'd love to mess around with the Kenwoods but I'm locked into Icom gear. I've compiled a ton of information about these radios, including the serial data. Do the Kenwoods have PC Control data sent over the serial port (similar to CAT on Ham radios)? It'd be great if Kenwood and Icom radios are compatible on that level -- all my data would then also pertain to Kenwood.

The Kenwoods DO have serial port capability. I haven't messed with it at all so I don't know if PC control data is also available. I agree w/u, it would be absolutely great if they were compatible in terms of PC control.

I also agree NXDN should be on more than just VHF and UHF and Icom should expand their product line.

[rescuecomm]

The information is interesting. It appears to indicate that one could split a 25 khz UHF channel into 5 channels if the coordinator would approve it? To be able to build out a county wide system using existing frequency allocations would be a bonus.

Bob

[N_Jay]

Originally Posted by rescuecomm

The information is interesting. It appears to indicate that one could split a 25 khz UHF channel into 5 channels if the coordinator would approve it? To be able to build out a county wide system using existing frequency allocations would be a bonus.

Bob

How do you figure?

6.25x4=25

[n1das]

Originally Posted by rescuecomm

The information is interesting. It appears to indicate that one could split a 25 khz UHF channel into 5 channels if the coordinator would approve it? To be able to build out a county wide system using existing frequency allocations would be a bonus.

Bob

I think it would actually be 4 channels (4 6.25kHz spaced channels, totalling 25kHz). With NXDN digital, being able use existing freq allocations comes as a bonus on top of everything else. This is one of Icom's talking points in their FDMA vs. TDMA paper. In many cases, all that would need to change on existing licenses would be an emission designator or two.

Icom and Kenwood have a viable 6.25kHz solution TODAY that works with existing freq allocations. OTOH, Motorola does not. To Moto, 6.25kHz operation means using a 2-slot TDMA system operation on 12.5kHz spaced channels, claiming to offer "6.25kHz equivalent efficiency". Even when the 2nd timeslot is unused when a MotoTRBO repeater is on the air, the whole occupied bandwidth of a 12.5kHz-spaced channel is still used. IIRC, the FCC still hasn't bought into Motorola's approach as a 6.25kHz solution.

My choice: NXDN 6.25kHz digital, offered thru Icom as iDAS and Kenwood as NEXEDGE. They are compatible in conventional mode only. Trunking locks you into either Icom or Kenwood. With Motorola's MotoTRBO, you're already locked into Moto even for conventional operation, and it likely will have to be replaced in a few years when the FCC eventually picks a date to migrate to 6.25kHz technology. Icom and Kenwood's solution is already future-proof.

[N_Jay]

It would be nice if there was a compatible set of FDMA and TDMA technologies.

While two 6.25 kHz channels looks more flexible, it is almost impossible to place them at the same site, or even at nearby sites, so if you want to load a site, TDMA is better. If you want site to site flexibility or simplex efficiency then FDMA is better.

Each company like to present the benefits of their solution and the deficits of the other. Both have both!

[N2DLX]

Originally Posted by N_Jay

It would be nice if there was a compatible set of FDMA and TDMA technologies.

While two 6.25 kHz channels looks more flexible, it is almost impossible to place them at the same site, or even at nearby sites, so if you want to load a site, TDMA is better. If you want site to site flexibility or simplex efficiency then FDMA is better.

Each company like to present the benefits of their solution and the deficits of the other. Both have both!

But the idea of FDMA @ 6.25 kHz is that you can be assigned channels from anywhere in the band. You can have one channel at 450 MHz and one at 470 MHz. With TDMA, you *HAVE* to be able to get a 12.5 kHz channel whether you end up using the full capacity or not.

In congested areas like NYC, 12.5 kHz channels are a little tricky to find. On the other hand, you can easily find 6.25 kHz channels scattered around. The fact that they aren't consecutive frequencies makes absolutely no difference to a FDMA system. While TDMA meets the "requirements" of the narrowbanding, it doesn't give the benefits of narrowbanding. Everyone has to occupy 6.25 kHz (and only 6.25) per channel for the benefits to be seen.

[pachanga22]

The problem with adjacent 6.25s is combining them. TXRX can do it certainly, but it is going to cost both your wallet and your output power. The insertion loss will be extreme. And you'd have to run some serious notch filters on the receivers if it is an inbuilding site with real high rx input levels or you'll crush the adjacent receivers. Too bad nobody makes extremely selective receiver front ends anymore like the old Mastr IIs.

[N_Jay]

Many people moving to these narrowband systems have existing channels, so when they split them they are adjacent.

at 6.25 kHz the TX loss would be ridiculous, and there are no filters good enough.

And even a hand tuned mastr II would not be tight enough for 6.25 adjacent.

[Radio76]

With 0 Kc combiners available you can put 6.25's end to end with about 6-7 dB of loss

[rescuecomm]

I was thinking about having the sites 3-4 miles apart. One in the northern part of the county, one in the middle at the 911 site, one at our existing site, and one in the southern part of the county. This would give almost complete UHF WT coverage using existing spectrum if techically feasable.

Bob

[pachanga22]

Originally Posted by N_Jay

Many people moving to these narrowband systems have existing channels, so when they split them they are adjacent.

at 6.25 kHz the TX loss would be ridiculous, and there are no filters good enough.

And even a hand tuned mastr II would not be tight enough for 6.25 adjacent.

True, but it's one of the tightest front ends I ever saw.

Ya know, I keep hearing and reading about people "splitting" their 25KC channels, and that's not the way I understand it works. As I understand it, the channel centers are staying the same. Because you have a 25KC license doen't mean you are licensed on the channel centers of any 6.25 channel centers within that 25KC. When someone renews a 25KC license, it comes back 12.5 on the same center, you don't get 2 12.5 channels back for your 25...Am I missing something? I haven't heard of anyone being licensed to 4 6.25 centers within a 25KC license.

[N_Jay]

Originally Posted by pachanga22

True, but it's one of the tightest front ends I ever saw.

Ya know, I keep hearing and reading about people "splitting" their 25KC channels, and that's not the way I understand it works. As I understand it, the channel centers are staying the same. Because you have a 25KC license doen't mean you are licensed on the channel centers of any 6.25 channel centers within that 25KC. When someone renews a 25KC license, it comes back 12.5 on the same center, you don't get 2 12.5 channels back for your 25...Am I missing something? I haven't heard of anyone being licensed to 4 6.25 centers within a 25KC license.

Yes, you are missing the idea of splitting your channel by narrow-banding on your center and requesting new allocations on the channels you freed up.

The center issue does cause a problem, as even at 6.25 you only get three usable channels, not 4.

You could request a waver to go to new centers and try to get 4 channels, but you would need to show tech engineering work to convince the FCC that your edges won't cause interference.

Additionally, much of this becomes much more difficult with shared channels and overlapping allocations (VHF).

That is why you use experts when licensing.

[pachanga22]

I actually know of, and advised against, some folks just programming repeaters on what they deem the 6.25 centers on "their" 25KC channel. I'm sure they'll cry foul if the FCC catches up to them and makes that license THEIRS.

[ElroyJetson]

I'm currently in the initial stage of designing an iDAS single site trunking system for a very interested customer.

Having had many Kenwood and Icom radios cross my tech bench over the past several years, my considered opinion is that Icom makes a better radio. With roughly equal numbers of Kenwood and Icom radios coming in for PM and service, I'm seeing essentially no warranty service issues on the Icoms but I've seen several Kenwood warranty service issues. New radios that fail in the field, very quickly. I don't see new Icoms coming back unless they've been beaten to death. Run over by a bus. Drowned.

Elroy