Narrow vs Wide Band

[captdan]

A quick question for the technical people - does it make a difference if I program my radio - for GMRS for wide or narrow band if I am only interested in communicating simplex between our own units?

 

For example - is one better than the other for use on MURS band ? will one go further ? Sound better ?  Does one penertrate buildings or other obsticales better ?

 

Same questions for using GMRS band ?

 

 

Thanks for any and all assistance ! 

 

Simple answers, (with maybe a very short tech explaination is ok),  are better for this old guy ! 

 

 

Dan

[JohnE]

you can expect to loose 5 to 7 percent in range and depending on the audio circuitry in the radio audio can sound good or bad.

I have had some in building issues w/NB, also I was running 650 narrow for a while due to adjacent channel interference and found a loss in horizon areas where I could talk through in wide before.

[captdan]

you can expect to loose 5 to 7 percent in range and depending on the audio circuitry in the radio audio can sound good or bad.

I have had some in building issues w/NB, also I was running 650 narrow for a while due to adjacent channel interference and found a loss in horizon areas where I could talk through in wide before.

 

SO ..unless there is a complelling reason I should keep the program set to wide band ?

 

Thanks!

 

Dan

[PastorGary]

Our own testing on UHF and VHF IG frequencies confirms what John E mentioned.  Narrowband is a distance loss format. 

[captdan]

Thank you both

 

This is one of the great things about this forum - techinical question from simple mind (me)  -  simple answer from brilliant minds !  (you)

 

 

Thank you !

[JohnE]

SO ..unless there is a complelling reason I should keep the program set to wide band ?

 

Thanks!

 

Dan

in a word yes. I put 650 back to wide and deal w/adjacent channel noise b/c in places where it was marginal it no longer worked.

basically a what is the lesser of 2 evils scenario.

[JohnE]

Our own testing on UHF and VHF IG frequencies confirms what John E mentioned.  Narrowband is a distance loss format. 

PG

     what did your testing yield?

[PastorGary]

PG

     what did your testing yield?

 

 

John, we had our IG equipment reprogrammed WAY before the Jan. 01, 2013 mandate, so we left the existing wideband programming in all of our UHF and VHF radios, which is legal as long as it is only used in an emergency as stipulated in 47CFR90.407.  

 

We tested each setup on three random days over a two week period in September 2012, so atmospheric condition changes could be averaged. Our test was simple... Using VHF high band SIMPLEX with CTCSS and a base station for MONITORING ONLY to a single mobile traveling on a US highway away from the base station and reporting in every 1/2 mile out past 25 miles.  We logged the mile post that the WIDEBAND signal was lost from the mobile - in this case it was 42.0 miles. We then had the same vehicle come back to the starting point and do it all over again, this time with the base station and mobile on the same test frequency and CTCSS but in narrowband.  The signal was lost at 38.5 miles, or just a little over 10 percent degrading of narrowband vs. wideband.

 

We then had the moble go back to the starting point and use UHF SIMPLEX with CTCSS in wideband.  The signal was lost at 34.5 miles.  Again, we started over and went to narrowband on both radios with the base MONITORING ONLY and the signal was lost at 29.5 miles. Again, just over 10 percent signal degrading in narrowband.  We did this same testing at the same time of the day on two additional days that month and the results were the same.

 

*Equipment used for VHF test:  Kenwood TK780G (H) radios, base and mobile with base radio MONITORING ONLY.  Mobile antenna was producing an ERP of 80 watts. 

 

*Equipment used for UHF test:  Kenwood TK863G  radios, base and moble with base radio MONITORING ONLY. Mobile antenna was producing an ERP of 35 watts.

[Linus]

There is no narrow band legal requirement yet for the GMRS channels. If you program for additional FRS channels (not the shared gmrs / frs ones), they must be narrow band and 500 mw or less to be compliant with FCC regulations. I have one of those bubble pack radios from a while ago and the manual shows the GMRS channels as wide and the FRS only as narrow.

 

For MURS look here (http://en.wikipedia.org/wiki/Multi-Use_Radio_Service) for the narrow band and wide band requirements. Some channels are wide and some are narrow.

The bandwidth is not the usual version that we are used to seeing on other services.

 

GMRS will escape a building pretty well. MURS will propagate further in an open area. MURS is limited to 2 watts.

[JohnE]

thanks for posting that up PG. your field testing about matches what we have experienced w/switch over. 

the in building repeaters suffered more that we originally thought they would in some cases. some of it was fixed w/higher power portables and more power out of the repeaters. in one case I tried an Rx preamp, that didn't work out too well.

[PastorGary]

I know, John... when you don't have very much modulation component to start with after being used to a 20K0F3E emission for 70 years, it's a slap in the face type of reality check.  This mandated manipulation of bandspace has political ties and lobbying from 'certain' companies as well as the new narrowband systems - especially P-25 - putting public safety personnel in harms way.  You won't read about radio failures costing lives, but it is happening.  But that's a discussion for another time.

 

By the way - IF your local fire department is using a 700 or 800 mhz trunked system as a FIREGROUND link, perhaps they should realize that a working fire puts out a wall of carbon particulate 'plasma' that some digital portable radios just can not transmit through.  If a firefighter is on the opposite side of a blaze from where the closest trunking tower is located, he or she may not have reliable comm... a disaster waiting to happen when fall back orders can not be heard or a request for additional personnel at a hot spot battle is requested. 

[Linus]

PG,

I have a friend who is a fireman. They switched over to 800 MHz systems. Everything goes through a trunked repeater. They have no simplex capabilities. This change makes it very difficult for them when they are trying to communicate to each other in the same burning building. Some changes are worse than the issue they are solving.

[JohnE]

FDNY is currently simulcasting on V and UHF for main dispatch but is using simplex and in hi rise cases portable repeaters on UHF all still wideband. from what I've heard PD an FD pretty much told the FCC to piss off. also most of NYPD's main channels are all up on T-band.

[GWOD]

hello

 

I am jumping in late here on this older thread and would like to get caught up.

Is the narrow band transmit mandate now required on all GMRS only designated 462/467 frequencies?

Any links to a reference are appreciated!

 

Thanks!

Greg

WQQI477

 

[PastorGary]

Not at this time - GMRS is a Part 95 radio service.  The narrowband requirement was applied ONLY to SOME Part 90 radio service frequencies above 54 mhz.  - however, every commission administration change brings 'new' ideas to bear, so anything is possible in the future.

[quarterwave]

PG,

I have a friend who is a fireman. They switched over to 800 MHz systems. Everything goes through a trunked repeater. They have no simplex capabilities. This change makes it very difficult for them when they are trying to communicate to each other in the same burning building. Some changes are worse than the issue they are solving.

 

You know, it is somewhat amazing to me that Radio people, and the agencies never think about this stuff, and accommodate it. However, a salesman will typically miss it....in my 25 years experience in radio. I think it is simply irresponsible and dangerous for any public safety or public service system to operate without a simplex option. 

 

A local (to me) PD and FD went to statewide trunked system a while back, and I am told they have no simplex. The existing VHF and UHF radio (which were in good working order) were zealously ripped out of the cars and trucks in favor of the new "toys"...which work great, but offer no back up to trunked or failsoft repeater operation. I am told they don't even have NPSPAC 800 simplex programmed. Leaving the radios that were narrowband capable (which were most of them) in the vehicles, and using it for back up would have been wise. The FD kept it's VHF repeater and simulcasts dispatches on it, but that's about it. The PD kept their UHF control base....but only to talk to the service department whom they gave the repeater and radios to. They don't even have the ability to use VHF interops from anything they own. 25 years ago every Sheriff's car, PD car, and HP car had VHF with at least 2 common VHF channels and bases all over our state. That was interops. Now they have pretend interops....patching a trunk talk group into another system and fighting with it and the training to get it to work. It's a shame. Sorry that was all off topic. 

[quarterwave]

On the system I admin, our VHF repeater performance is likely degraded some due to Narrow Band, but we are not really noticing. The system has always been over-built (that is a Positive!) with a 75 mira license and it's good for 300 Watts (500 ERP) on a repeater that is on an awesome site. Our split is also 8 Mhz...so it's a great performing setup. We only run 100watts at the antenna...haven't needed to up it.

 

I have seen less range out of our mobiles on simplex channels, we use 2 freqs for site work, portables and truck to truck in transit. I would put usable range down by up to 30%.

[GWOD]

Thanks Pastor Gary. Is there a GMRS "standard" among the community for a default CTCSS tone on the 462 simplex frequencies especially on the traveler channel or for emergency comms? Or are those usually monitoring 462 just use no tone?

[PastorGary]

I don't use GMRS simplex very often, but if I remember correctly, the unofficial 'standard' is 141.3 CTCSS.  I am unaware of any unofficial DPL standard being used simplex nationwide for travelers or emergency comm at this time, but others here may have more up to date info than I have.

[Logan5]

I listen to 3 of the GMRS channels, open, 600, 650, 675. these are our locals. I just activated the standard travel tone on 600. and we are thing of swapping location for 600 and 675, since as I recall, 675 is the standard for Emergency communications. either way 675 makes a lot of sense if you are just listening or are starting your own repeater in an un-serviced area. All though our new equipment is capable,  We do not plan to use Narrow since it is not required on part95.   

[GWOD]

Logan5

 

Thanks for the insight. My reason for the questions are:

If I am monitoring for local activity then no receive CTCSS is best on 462 channels.

If signals are received, then the question of a transmit tone comes to surface for 462 channels.

 

So it appears reasonable to simplex receive with no CTCSS tone on 462 simplex, and transmit on the unofficial but likely 141.3 to open the squelch of those who might be using a tone.

 

On repeaters I imagine (like the ham bands) that tone is typical to reduce interferance and limit users.

 

On your 600 with 141.3 activated do you mean transmit or both TX/RX? Sounds like a repeater you are speaking of - correct ?

 

Thank you!

[Logan5]

Yes we just upgraded to a Bridgecom BCR-40U so I have programed 22 CTCSS tones and one CTCSS to DCS tone. the standard travel tone is one of them. there is also a sysop tone that allows remote programing vis DTMF.  If you are listening for potential "Emergency" calls out for help. you would want to listen to the open channel with out any RX CTCSS or DCS tone. However it is likely this type of call out could come in on any of the GMRS and or FRS channels. GMRS is an unlikely place to find help from strangers in the event of an emergency. Yes I have the travel tone set up to RX and TX, but keep in mind only other hand set's set to 141.3 or open scanners will hear you if you use the travel tone. yes the tone is meant to weed out others, limiting the amount of noise and convo you are not part of or interested in. It does not offer any technical privacy. I have several scanners, I can listen to a channel "OPEN"  or program any CTCSS and or DCS codes of party's I wish to listen in on. Since we have a lot of Illegal business use in this area.