Batboard

I was recently told that it was illegal to cross band from a UHF conventional channel or repeater with a VRS that then transmits via an ASTRO Spectra. The equipment is, of course, irrelvent, it's more the concept and setup that I'm pointing out: Conventional or Repeater, UHF into an 800 trunked system.

If the conventional/repeater is licensed for public safety use, and there is a letter of permission from the 800 system administrator, is it still illegal in the eyes of the FCC?

I've searched through Part 90 for anything related to cross band operations, but theres only one small paragraph that has nothing to do with this.

Anyone that might be able to shed some light on this, especially a section from 47CFR90 that allows/disallows it would be greatly appreciated!

I've never heard of such a thing and it is done all the time by people who can't afford a ton of astro portables but have an astro mobile.

The equipment is not irrelevant, and the FCC Rules establish the legal conditions.

If the equipment you describe is placed at a FIXED location it is NOT considered to be a vehicular repeater. A vehicular repeater is ONLY authorized to extend the communications range of hand-carried units (see 90.247). It is NOT authorized to link fixed stations or systems operating in different frequency bands. Therefore the equipment you describe must be licensed and frequency coordinated per FCC rules as a fixed repeater station (station class FB2). It must meet the transmit frequency stability requirements for FIXED stations in the listed frequency band (see 90.213). Very few portables or mobiles are certificated or were type-accepted as complying with the 2.5 PPM requirements on UHF, 1.5 PPM in 806 or 1.0 PPM in the NPSPAC 821 MHz sub-bands. The Astro Spectra whether UHF or 800 is not approved.

Those requirements are clearly laid out in the FCC rules. In general, things that are acceptable in a low-profile mobile application are often prohibited by the FCC for use in a high visibility, wide area environment unless there is an overwhelming technical justification for allowing the non-compliant use. Local budget relief is not a category that the FCC tends to favor in this situation. In my opinion you could have a good case for getting an FCC waiver to allow cross-band linking between the nationwide interop channels on LB and HB, or HB and NPSPAC CALL; that's what those interop channels are for.

There's also an issue of being able to monitor the opposing band's receive channel before transmitting on it. Many folks completely ignore this, assuming that they have exclusive use of "their" channels because they don't hear anyone else most of the time. 90.403e requires licensees to take reasonable precautions, including monitoring the transmitting frequency for communications in progress. If your cross-band repeater was configured such that a trunked user could listen to the UHF channel in carrier squelch (CTCSS disabled) before transmitting, then you would comply with this separate section.

But this is a VEHICLE REPEATER (hence "VRS"). I don't see anything fixed about what he is describing.

Thanks, Karl. I should have been more specific about the setup.

It is a mobile system, Motorola VRS, connecting to an Astro Spectra - all in a vehicle. It really is a mobile repeater in the truest sense, and the portables are set to 2W on the mobile repeater frequency as required. It all seems legit to me, but some people just seem to think that it isn't.

On a similarly related topic, does the FCC dictate how a cross band repeater is operated? Instead of a bunch of mobile repeaters, would it be legal (with written permission) to just connect our legally licensed/operated repeater to a Spectra and operate it as a cross-band setup?

I don't see any FCC sections that specifically address the permissability/prohibition of cross band setups. Is it safe to presume that they are allowed in a public safety environment if both sides have written agreements?

Looking at what I wrote, I did not mean to be as harsh as it might have appeared. I've recently had to "retrain" some folks trying to implement a full cross-band, cross-mode link using mobile boxes and a big 12VDC power supply, with gain antennas about 50 feet up.

From your explanation I would say that both your equipment and the application appear to be in full compliance with the rules.

However, 90.247 defines (and therefore limits) the communications that can be relayed. The VRS is not permitted to repeat conversations from units other than portables over to the mobile, which is on a trunked system in your case. Therefore the CTCSS tone that a portable uses to activate the VRS must be different from the regular tone used on the UHF repeater. From practical experience it also should not be the connect tone used on your Motorola trunking system.

The rules do NOT prohibit cross-band repeating, and lots of folks do cross-band using a patch on their consoles. Having a human there means that somebody is listening, which covcers the monitoring requirement in 90.403e. Standalone cross-band links are more work because it's hard to listen on the UHF channnel when your radio is trunked 800, but there are well-designed interfaces from several suppliers that do check for co-channel signals before they enable PTT of the other-band station.

Remmber the coordination requirements. If incoming signals are being automatically retransmitted on more than one band, both stations are mobile relays and the license should include both inputs and both outputs under a single callsign. The FCC has decided that stations in different categories (PW for HB or UHF PS pool channels and YF for NPSPAC trunking) must be on separate applicaitons and therefore will have different call signs.

That's where you should request a waiver to put both on a single piece of paper, and use the "I" word to justify. Interoperability gets more favorable treatment today, especially when the local APCO, IMSA, etc. frequency advisors attach comments in support. Particularly important if that UHF channel is not managed by the same coordinator as your 800 system.

The following came up when I submitted the reply above:

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[yup, we are aware of the problem, this has been covered in the general forum. This is why you should aways read your stickies and announcements!!!!! Posts and PM's work, email notification does not. -Alex]

There have been a number of people commenting about the error. Allex knows about it and will get it fixed when his time permits.

I have a question about using the I designator on a license. Can you give me a call sign of a station that you know has it done that way. I would like to see just how the paperwork was set up. Have a number of public safety systems that I am working on that will probably end up with some cross band links or patches for some extended times until the legacy equipment is taken down.

Jim


[quote="Karl NVW"]The following came up when I submitted the reply above:

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[yup, we are aware of the problem, this has been covered in the general forum. This is why you should aways read your stickies and announcements!!!!! Posts and PM's work, email notification does not. -Alex][/quote]

The error seems to have gone away tonight, at least i'm not getting it right now while posting or sending PM's.

Looks like they kicked the server and blew out the dust bunnies and got it working again!