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Author Topic: 2 way radios  (Read 4161 times)

Ray Aberle

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Re: 2 way radios
« Reply #10 on: May 07, 2017, 01:44:53 am »

Ray,

Did you go get your license on your own or did you have a vendor do it for you? I just spoke to Bearcom and they wanted to handle it for me said I can't do it on my own. Seems strange.

I already have an FRN, but what class of license do I need to apply for?
Not wanting to dump a bunch of people asking for help on his lap........... but Henry helped me get my appropriate license setup. I just paid the fee to the FCC; I don't remember what that was, though, because it was a couple three years ago (and I barely remember last week... ;) ).

Ray - What region did you get you frequencies coordinated?
To be candid, I'd have to ask Henry. He put in the best options for me, in his experience.

-Ray
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Kelcema Audio
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Henry Cohen

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Re: 2 way radios
« Reply #11 on: May 07, 2017, 07:46:40 pm »

First to the topic of which radio: Presuming one is looking for a fairly durable unit with high reliability, the Motorola CP200d (and the discontinued CP200) are quite prevalent in the entertainment and A/V markets with lots of inventory at radio rental houses. The other Motorola product at this price/performance/size in widespread use is the XPR3000 series, with the 3500 having a display. Both are solid performers but you will pay a premium for the batwing.

If you're not hung up on buying the big M, The Hytera DMR (digital mobile radio) line, specifically the PD5, PD6 and PD7 series, are every bit the Motorola equivalent at about two thirds the price. Even the lower tier PD4 is quite a good radio at a very nice price point (we just put 150 into our rental inventory for those who want a smaller radio). Further, as long as a DMR radio is programmed with standard DMR channels, different brands can talk to each other in digital mode. Only Tier II pseudo-trunking and advanced encryption are proprietary to each brand.

In addition to Hytera and Motorola, other good DMR radios are manufactured by Tait (expensive and very good), Klein (under the Black Box" brand; inexpensive and uses cheap microphone, speaker and analog audio amp) and Vertex (also doesn't sound very good due to cheaper analog audio component choices).

Kenwood and Icom offer excellent analog/digital radios as well, but they use the NXDN (FDMA) standard and thus incompatible with the DMR (TDMA) products mentioned above when in digital mode.

I'm concentrating on digital radio offerings, and DMR in particular for a few reasons: a) At this durability/performance/reliability level and expected ROI, you're looking at the same general pricing as an analog only radio; b) These radios provide the option of operating in either conventional analog mode or digital on a per channel basis, which means backward compatibility and compatibility with most of the available rental inventory; c) Digital radios offer a number of advantages in spectral efficiency, range, less susceptibility to co-channel interference, and channel loading.

With respect to licensing in the US, business uses in either VHF or UHF require a license, except for the VHF MURS frequencies, which is license by rule (except for foreign entities). The itinerant frequencies in either band require only a license, not FCC frequency coordination. If you want more frequencies than the five VHF or four UHF itinerant, you'll need to obtain frequencies from one of the FCC designated frequency coordinators for the business station class "IG". Someone mentioned Forest Industry Telecommunications; I'll second that recommendation. Nice group of folk with quite good pricing. They will handle both the coordination and license application/filing.

One last note regarding programming capability for radios. No reputable manufacturer makes their programming software available to the end user, unless it's a large entity with a dedicated compliance person/department (generally public safety and utilities). Motorola is particularly diligent about this, and has been since their advent of computer programmable radio equipment.
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Henry Cohen

CP Communications    www.cpcomms.com
Radio Active Designs  www.radioactiverf.com

Stephen Swaffer

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Re: 2 way radios
« Reply #12 on: May 08, 2017, 10:56:28 am »

Henry,

Thank you for taking the time to chime in-your informatio was/is very helpful!
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Steve Swaffer

Brian Adams

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Re: 2 way radios
« Reply #13 on: May 08, 2017, 04:32:22 pm »

I have 6 Motorola RMU2050's, which are MURS radios, and I purchased these based on a friend's recommendation who had good results with them in a small theatre. On my first show out with them they were barely adequate. They just don't have the range I need for outdoor shows and the earpiece is fairly quiet. I haven't been able to sell them so I still occasionally use them for small theatre shows, but I certainly wouldn't buy anything like them again.

If your shows are anything like mine I would absolutely recommend something higher wattage, which is going to require a license. I've had good results with Motorola RDU4100's, which is a 4 watt UHF radio. During rock shows I wish it had a little more volume out of the earpiece, but that would be my only real complaint with that radio in particular. They're a lot louder than my RMU2050's. In general I think I'd be comfortable with anything in the 4-5 watt range, but the RDU4100's are good enough for me for now.

I'm going to look into Henry Cohen's recommendations for my next round of radios. It's safe to say he knows a lot more than me about RF, and probably a lot of other things too!
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Brian Adams
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augie propersi

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Re: 2 way radios
« Reply #14 on: May 09, 2017, 09:46:38 am »

I am sticking with my analog Motorola HT1250/750 as long as we can, even though they are discontinued, analog = no delay good sound quality, repairable and there are lots of them around used & new,

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Steve Ferreira

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Re: 2 way radios
« Reply #15 on: May 09, 2017, 11:38:33 am »

We decided that the upkeep and everything else that comes with radios was too much for us. We just cross rent now from a dedicated two way radio company. They pay for all the licenses and maintain the units. Yes it's a bit of a drag that we have to go to them for pick up and drop off but the pros outweigh the cons for us.
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Tim Hite

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Re: 2 way radios
« Reply #16 on: May 30, 2017, 10:40:01 am »

First to the topic of which radio: Presuming one is looking . . .

Henry, thanks for getting me on track. Ray, thanks for sending Henry.
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Bad Quail
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Tom Provenza

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Re: 2 way radios
« Reply #17 on: June 07, 2017, 09:33:08 pm »

Even though Henry has hit most of the concerns, I will jump in with a couple comments (day job is with the big M). For use in audio production I would stick with UHF, In my experience VHF has always been more susceptible to coupling into audio circuitry in close proximity. Nothing worse than keying a radio and hearing a big thud through the system. 

Also a big DMR fan, which reminds me of another offender in audio systems- TDMA. Due to the nature of TDMA, it could also cause noticeable pulses as the transmitter cycles on and off (remember Nextel /iDEN?). Only an issue with DMR if using a repeater which would be uncommon in most production work

One last option worth mentioning is the 900Mhz spread spectrum radios. The Motorola DTR series, and I believe there may be another manufacturer as well. Very good range & performance, little chance of destructive interference and co-channel issues, and license free.



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Tom Provenza

Henry Cohen

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Re: 2 way radios
« Reply #18 on: June 08, 2017, 05:30:50 pm »

Even though Henry has hit most of the concerns, I will jump in with a couple comments (day job is with the big M). For use in audio production I would stick with UHF, In my experience VHF has always been more susceptible to coupling into audio circuitry in close proximity. Nothing worse than keying a radio and hearing a big thud through the system.

Agree with the UHF recommendation, but for a different reason: propagation. Given the typical venue and immediate surroundings, the shorter wavelengths tend to work better in hallways, tunnels, between floors, etc. With modern audio equipment design and manufacturing, RFI demodulation is far less a problem than it used to be. That said, keying any 4-5 watt radio anywhere near audio (or video) equipment, or low level copper signal cabling, is strongly discouraged. Radios assigned to FOH or monitor mixers should be set to low power (about 1 watt).


Quote
Also a big DMR fan, which reminds me of another offender in audio systems- TDMA. Due to the nature of TDMA, it could also cause noticeable pulses as the transmitter cycles on and off (remember Nextel /iDEN?). Only an issue with DMR if using a repeater which would be uncommon in most production work

Again, not the problem it used to be. The old GSM/TDMA protocol was actually cycling the transmitter in the radio or phone on and off, and it was the transmitter key up that was the primary source of the noise. With DMR, the transmitter is always on for the duration of the key press (or the carrier detect in the case of a repeater); the TDMA aspect here is the cycling between data streams for the two time slots.


Quote
One last option worth mentioning is the 900Mhz spread spectrum radios. The Motorola DTR series, and I believe there may be another manufacturer as well. Very good range & performance, little chance of destructive interference and co-channel issues, and license free.

The DTR 900MHz radio does eliminate the licensing issue, has terrific range and is overall a great radio but for the battery design IMO, a removable plastic cover and a cellphone style battery. The battery compartment door is too easily dropped, lost or broken. The only consideration is for any other 900-928MHz ISM equipment that might be on the event or installed in the venue: high power cordless phone system, machine-to-machine links (M2M for vending machines), HVAC remote control/monitoring, wireless DMX, rigging load cell monitoring, etc.
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Henry Cohen

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Tom Provenza

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Re: 2 way radios
« Reply #19 on: June 08, 2017, 09:40:08 pm »

Thanks for your comments Henry, all good points, especially in the production environment.

However I will disagree with you on TDMA transmitter function. The DMR subscriber units do in fact cycle the transmitter if operating on a repeater, same as P25-P2. This allows the subscriber to actually receive data in between TX bursts which enables advanced features such as transmit interrupt. It also has led to manufacturers claiming increased battery life. If there was a constant carrier from the subscriber, there would be no way to utilize the opposite timeslot as there would be RF contention. The DMR repeaters do transmit constant carrier if active on one or both timeslots, or in hang time or beacon.  The same cycling also occurs in M's proprietary Dual capacity Direct mode.

I can't speak to what is happening in the cellular world & GSM

A little beyond the original intent of this thread, but figured i would clarify
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Tom Provenza
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