Proper hardware for a cross band Simulcast

[chiefhal3]

I have been reviewing various threads and made posts on several as well as gotten quite a bit of replies to this idea. However, the only solutions I have gotten that really make sense and are of a reasonable price are really aftermarket type work arounds and not really a part of the systems main controllers or repeaters.

What is the Motorola way if you will to simulcast a VHF conventional repeater on to a talk group of an 800 mHz trunked system? I have the ability to put the hardware at the actual tower sites of the 800 system or the VHF system which by the way are in different locations. I would appreciate model numbers and approxiamate costs if possible.

Further info, the 800 is a Motorola Type II mixed mode trunked APCO25 system with six satellite recievers hooked up to two sites that are simulcasting each other. The VHF is a conventional repeater with one satellite reciever. The satellite receiver is actually a repeater that is being used as a satellite but in the event the main repeater goes down it takes over.

The basic functionality we are looking for is that the VHF system will be able to monitor and transmit back to a single talk group on the 800 trunked system which will also have the ability to monitor and transmit back to the VHF system.

[xmo]

"...What is the Motorola way..."
__________________________

The "Motorola" way requires a console that is part of the system. The VHF conventional channel would be connected to a BIM [Base Interface Module] in the Centracom CEB [Central Electronics Bank]

The 'simulcast' is effected through the console "patch" function. There are two ways to set that up. Either operator initiated or permanent. Operator initiated simply means one of your operators sets that patch up when it is needed.

Permanent patch is established by the console programming software [e.g. CDM - Console Database Manager]. In a Centracom Gold environment permanent patch can only be programmed into button LEB operator positions - but - the position does not have to have an actual hardware op - it can be a 'virtual' op.

Plus & minus evaluation:

On the plus side the patch is an integrated part of the system - there is nothing mickey mouse involved. Another plus is that the trunking system will only pass the traffic from the conventional channel if there is at least one trunked radio affiliated with the patched talkgroup.

Minuses are that you can't patch a patch, i.e. if you have a particular talkgroup involved in a permanent patch no other operator can patch either that talkgroup or the conventional channel to any other radio resource.

Another minus concerns scan. If you have trunked users with this talkgroup in their scan lists but there is no physical radio affiliated with the talkgroup - no traffic gets patched to the trunking system and the scanning users don't hear the VHF traffic.

Your other alternative is a linking scenario. This can be a stand alone device comprised of back to back radios - one each on the VHF side and one on the trunked system - this is where mickey mouse sometimes gets involved with a couple of cheap radios kluged together.

I prefer to set up the link by directly interfacing the VHF repeater infrastructure to a fixed trunked control station - preferrably with console remote control enable/disable.

The linked scenario will always pass the VHF traffic to the trunked talkgroup regardless of whether there are any other trunked radios affiliated since the link radio itself is affiliated. That can be either a good thing or a bad thing depending on the specifics of your application.

Regardless of the approach taken - console patch or linker - I think it is very important to use a hardware handshake interface. The traditional patch got its bad rap for a good reason - traditional VOX has a pick up delay that results in audio truncation that is compounded by the trunked system access delay.

By using hardware handshake [e.g. COR] and adding an audio delay module, the cross connect between the two systems can be seamless with no truncation issues. If COR handshake can't be implemented - some of the new linking systems [e.g. JPS] employ a "smart" VOX system that is microprocessor based to properly sense voice activity plus they include audio buffering to eliminate truncation.

[RKG]

xmo: Are you completely sure that you can't patch a patch? I'm not challenging, just asking, and the reason I'm asking is that I think I've seen data printouts where 2 or more talkgroups were patched (into a new temporary talkgroup) and then that patchgroup has been patched into another talkgroup.

Or have I just answered my own question: what I've seen is patches within the trunking controller, not between the trunked system and a conventional channel within the CEB controller?

I should add: not only am I too tired to go pawing through the SmartNet manual, but the last game of the World Series is about to start.

No, actually my wife says it started a couple of minutes ago and the Charlie Manson lookalike just homered.

[nmfire10]

If it is an operator controlled patch, you CAN add to the patch. Lets say you have "Patch 1" set for Talkgroun 1 to VHF. If you want to patch another console resource to one of those two., you would have click on the patch button and add that third resource to the patch. The result would be three resources on "Patch 1" rather than two.

You can NOT make a resource that is in Patch 1 be part of any other patch. You need to put them all in the same patch group.

[xmo]

In the original post I gave this as a sort of warning: "...if you have a particular talkgroup involved in a permanent patch no other operator can patch either that talkgroup or the conventional channel to any other radio resource. ."

Notice I said permanent patch. Operator initiated patches can have members added or deleted as the operator chooses with the restriction that no one resource can be a member of two patch groups at the same time.

Permanent patch is used when the connection between the two resources is intended to be full time and it is desired to NOT have operator intervention required to initiate the connection.

Most op positions today are Elite [Smartzone / Smartnet systems] You can NOT have a permanent patch on an Elite op. Permanent patch is only possible on 'Classic' ops. If you have a Gold console system with Classic CRT ops, then you could have permanent patches on 'live' ops, but if you choose to create a virtual op for the purpose of supporting permanent patches it has to be button LED. [You could create a Classic CRT op without the actual op hardware - BUT - when the COIM for that position is initialized it will come up disabled waiting for input from the op]

Since the permanent patch in most systems has to be created on an op that does not actually exist - it follows that other resources cannot be added to such a patch. Likewise resources that are part of ANY patch - permanent or operator initiated at one op cannot be added to another patch at any other op.

[chiefhal3]

From the replies it is obvious that this can be done on the 800 side via the control systems and consoles. I guess the only thing I need some clarification on is how the VHF system will be accessed by the 800 since they are not at the same sites. Is it best to do this over the air by having a base unit on the VHF system installed at the 800 system, or, would it be better to link them via a dedicated phone line? Either option shouldn't be a problem. One obviously has a one time cost while the other has a recurring cost and the risk of being disconnected. What normally seems to be the most reliable link?

[RKG]

To simply matters (perhaps greatly), a "console" is really just a large tone-controlled remote, which is capable of reaching out (via tone termination panels or otherwise) to more than one radio. So in the context of your question, a console could access the 800 system either via a mobile radio or via the trunked controller directly, and it could access the VHF system either via a mobile radio or via the base station directly. In either case, the patch is simply an audio bridge and a logic matrix that "keys" both radios when someone else has "keyed" either of them.

When you take a look at what you called "third party" solutions to the problem, you find that, functionally, they work the same way. For instance, the RC-200 by KR Nida (which we have used successfully in a couple of applications) is basically a box hooked to two (or more) mobiles, each of which has access to one system. The box bridges audio and "keys" the other radios when any of them is receiving.

[/\/\y 2 cents]

It is bascially buying backwards if you use a leased line. That kind of thinking is very 1960's. Then you have microwave as the other option, which not only has a high upfront cost, but high total cost of ownership for the recurring site fees. The same thing/effect can be accomplished with no total cost of ownership issue and very small upfront capital cost by going with a VoIP interface such as SiteCast and all you need to have is internet and a spare radio at each location. The more SiteCast's you have the more you can connect sites into one another-via DTMF from the field, or with a fixed operator at the control point. Leased line is dead and microwave is for only the most robust of site applications where the cost can be justified. What you want and seem to be expressing the need for is a 3rd party work-in that adapts to the exisiting infrastructure already in place and efficently simulcasts both systems into one another, skirting the turnking handshake issue. Yes, your problems/needs can be met with a $75,000 console and $2000 interface cards that hook into leased lines that cost $1000/mo. plus maintence all associated fees and you'll get what you want. And by the way, thats the Motorola way that you refer to. But that is DUMB and to go from hooking up the Audio and COR of a Maxtrac and GTX (quick fix) to something that is on the other end of the spectrm (only able to be afforded and warranted by the largest of public agencies) is like trying to ballance a see-saw with a 5000lb. elephant vs. a 20lb poodle. They are not in the same class. There are heavyweight (and wasteful) solutions (the motorola way), temporoary solutions (your maxtrac GTX crossband setup) or reliable, cost-effective and responsible (VoIP switchable on-the-fly links) The latter gives you as good quality of service (QoS) and low cost. The EasyLink setup you refered to is a good choice, but it isnt as flexible or software define-able plus is range dependent because ut uses radio waves..Telephone lines are not range dependent in a quality of service perspective, but are range depedent because of a cost issue....you can have all the range you want but it is going to cost $1000 per increment. The internet on the other hand, while there more than 99% of the time (the only real claim against it is if the internet sevice you use goes down) you pay no amount for distance with the same quality level as a leased line. It's like the best of both worlds.

[chiefhal3]

I understand where you are coming from and I do think you have both good opinions and probably a via-able product that I may still utilize. I am really just considering all the options. I really like the idea of using two mobiles set up on both systems and linking them together because I have control of what is happening. But I am also exploring doing it at the 800 system site as that site is maintained with all kinds of maintenance, backups, etc. that I may not maintain as well at my dispatch location. Plus the 800 site and system does already have all the expensive Motorola Controllers and Cards, and Consoles. I just don't know if they are going to allow my equipment to be installed directly on the system or not but I want to know how it would be done if they do end up allowing me to do so.

I have a meeting in the coming week or two with the operators of the 800 system to discuss the additional access they are giving us. At this point I don't really know what all they are going to allow us to do until we meet to discuss it but from a preparation standpoint I wanted to know my options ahead of time so I can beprepared and hopefully end up with the best service at a reasonable cost to both them and me.

At this time I don't even know if they are going to give me any talk groups of my own or if they are only going to let me access their existing talk groups. If they give me my own talk groups I am going to want to try and link them to my exisiting VHF system so that my guys with 800 radios don't have to carry two radio on their side. If they don't give me any talk groups but only access to their existing one the whole linking deal is dead.

Also, I have a second project I am working on that is totally separate from all this. That is what I called you about but when we talked it sounded like your solution for my second project would actually work for me first. That is why I am so interested in what your system has to offer, especially with the ability to access it from the internet world wide.

[wavetar]

I'm not sure what your cost considerations are, but we have had tremendous success with the MobexII unit from Futurecom. The unit I'm referring to has a built-in VHF repeater, which can also be programmed simplex if desired. You provide the 800MHz radio, which can be either an Astro Spectra W4 or MCS2000 Model III (GE Orion is also another choice). The units have to be remote-mount versions regardless of which one you choose, since the MobexII integrates directly between the transceiver & control head. The unit is small enough to mount in a vehicle if desired, or sit in a corner of an office, or be located on-site...whichever is prefered. They can be set-up for full-time crossbanding, or can be brought up with a DTMF command from a VHF unit. The audio is incredible, with zero delay. A nice feature is 'trunked error tones' for your VHF radios. Normally in a crossband situation, if you talk on the VHF radio and the trunked side of the crossband could not transmit for whatever reason, the VHF side has no way of knowing this. With the MobexII, the error tones will be sent on VHF at the end of the VHF transmission, letting you know the trunked users didn't hear you. I can't say enough good things about these units. The only con is the cost, since they are truly a high-end product, but they otherwise cannot be beat. If this interests you, more information can be found here:

http://www.futurecom.com/mbx_nf.htm