FRS vs. GMRS - coverage area

Licence free two-way radio services that now includes both FM and digital channels. Discuss models, modifications and other similar worldwide standards such as FRS and GMRS.
Post Reply
rooth
Regular
Regular
Posts: 24
Joined: 27 Mar 2017, 19:29
Location: Roma

FRS vs. GMRS - coverage area

Post by rooth » 28 Nov 2017, 19:09

What is the difference as the coverage area if I emit 0.5W in FRS versus 0.5w in GMRS.
Does anyone know to explain?

User avatar
Admiral
Legend
Legend
Posts: 10000
Joined: 08 Mar 2011, 21:20
Call Sign: 26TM157
Location: MK-UK

Re: FRS vs. GMRS - coverage area

Post by Admiral » 28 Nov 2017, 19:43

None at all as half the channels are shared between FRS and GMRS and the rest are a gnats willy away.
Winner of the 2017 IBTL 'Summer Sizzler' competition

User avatar
radiosification
Top Poster
Top Poster
Posts: 2434
Joined: 27 Dec 2010, 23:52
Location: North London
Contact:

Re: FRS vs. GMRS - coverage area

Post by radiosification » 29 Nov 2017, 00:19

Your location is showing on your profile as Romania. FRS and GMRS are for use in the USA and it is probably illegal to use them in Romania. In Europe we have our own version which is legal here, called PMR446.

Apologies if you knew this already but since you're quite a new user and are asking about this stuff when you're in Romania, I thought I better tell you just to be sure.
If you're interested in digital voice, check out my YouTube channel:
http://www.youtube.com/radiosification

rooth
Regular
Regular
Posts: 24
Joined: 27 Mar 2017, 19:29
Location: Roma

Re: FRS vs. GMRS - coverage area

Post by rooth » 29 Nov 2017, 16:03

@radiosification:

My question was generic. I see 0.5W FRS / GMRS devices that say they emit 10-15 miles and look the same as the 0,5W PMR of Europe.
I was wondering where the big difference in coverage is ?

User avatar
kilimax
Veteran
Veteran
Posts: 2649
Joined: 05 May 2014, 09:18
Call Sign: GM0BRJ
Location: Same Country as Buick Mackane

Re: FRS vs. GMRS - coverage area

Post by kilimax » 29 Nov 2017, 19:29

rooth wrote:
29 Nov 2017, 16:03
@radiosification:

My question was generic. I see 0.5W FRS / GMRS devices that say they emit 10-15 miles and look the same as the 0,5W PMR of Europe.
I was wondering where the big difference in coverage is ?
Optimistic advertising! :lol:

Range will depend greatly on, and is a combination of power, receiver, antenna and terrain. Terrain is especially important at UHF.

As these allocations are essentially the same, assuming you had PMR446/FRS/GMRS equipment side by side, with same power, antenna and receivers were of similar spec, you should expect to achieve a similar range.
Kilimax - Drew
Amateur Callsign GM0BRJ
Tango Mike Callsign 108TM144

I've changed radios that many times, I've forgotten what I have :think:

rooth
Regular
Regular
Posts: 24
Joined: 27 Mar 2017, 19:29
Location: Roma

Re: FRS vs. GMRS - coverage area

Post by rooth » 30 Nov 2017, 07:35

And then where is the difference of coverage up to 35 miles even to those FRS or GMRS 0.5W power assuming we are in the free field. However, the PMR do not pass 8-10 km maximum under ideal conditions.
Is it somewhat higher frequency?

User avatar
M3HIM
Radio Addict
Radio Addict
Posts: 650
Joined: 08 Apr 2010, 14:32
Call Sign: M3HIM
Location: Aylesbury, Buckinghamshire, UK - IO91ot
Contact:

Re: FRS vs. GMRS - coverage area

Post by M3HIM » 30 Nov 2017, 15:15

FRS and GMRS share frequencies in the 462MHz and 467MHz bands with unlicensed users limited to 0.5W. PMR446, as the name implies, uses frequencies in the 446MHz band with a limit of 0.5W. As all three services operate on similar frequencies and power levels, the coverage area is similar and typically 5-10km in open space but much less in an urban environment.

However, licensed users of FRS / GMRS can operate on higher power (2W, 5W, 50W) depending on the channel range in use and GMRS also supports duplex repeaters.

PMR446 (analogue) and FRS use 2.5kHz FM deviation whereas GMRS uses 5kHz FM deviation which can improve signal range.

Some unscrupulous advertisers may quote coverage area based on use of repeaters, external antennas or higher power which is not available to unlicensed users.

So, generally speaking, 0.5W simplex with an integral antenna on UHF will get you 5-10km with terrain and conditions allowing greater coverage in some circumstances but much less in others.
Félim M3HIM
26-CT-909 / 26-TM-989 / 26-FRS-001 / 26-IRC-909 Aylesbury, Buckinghamshire, England/UK [IO91ot]
29-CT-909 / 29-TM-989 / 29-FRS-001 / 29-IRC-909 Sandymount, Dublin, Ireland/Éire [IO63vi]

User avatar
kilimax
Veteran
Veteran
Posts: 2649
Joined: 05 May 2014, 09:18
Call Sign: GM0BRJ
Location: Same Country as Buick Mackane

Re: FRS vs. GMRS - coverage area

Post by kilimax » 30 Nov 2017, 18:00

rooth wrote:
30 Nov 2017, 07:35
And then where is the difference of coverage up to 35 miles even to those FRS or GMRS 0.5W power assuming we are in the free field. However, the PMR do not pass 8-10 km maximum under ideal conditions.
Is it somewhat higher frequency?
They operate on the same general part of the UHF spectrum. It's the advertising that's incorrect.
Are you reading this information from somewhere or actually have evidence that this is the case? I ask because there is no "practical" difference between these bands. Is this line of sight (point to point) or through a repeater? Anyone can get 40 miles through a repeater.
As I previously posted, if you had identical equipment on these bands, you would expect the same coverage. You cannot simply magic an additional 25 miles from nowhere.
Kilimax - Drew
Amateur Callsign GM0BRJ
Tango Mike Callsign 108TM144

I've changed radios that many times, I've forgotten what I have :think:

User avatar
M3HIM
Radio Addict
Radio Addict
Posts: 650
Joined: 08 Apr 2010, 14:32
Call Sign: M3HIM
Location: Aylesbury, Buckinghamshire, UK - IO91ot
Contact:

Re: FRS vs. GMRS - coverage area

Post by M3HIM » 30 Nov 2017, 20:32

From Wikipedia: "The best known [PMR446] long distance record is 333 mi (535.8 km) from Blyth in the United Kingdom to Almere, Netherlands. This was the result of enhanced propagation conditions, not a line-of-sight signal."

https://en.m.wikipedia.org/wiki/PMR446?wprov=sfla1
Félim M3HIM
26-CT-909 / 26-TM-989 / 26-FRS-001 / 26-IRC-909 Aylesbury, Buckinghamshire, England/UK [IO91ot]
29-CT-909 / 29-TM-989 / 29-FRS-001 / 29-IRC-909 Sandymount, Dublin, Ireland/Éire [IO63vi]

Post Reply

Who is online

Users browsing this forum: No registered users and 2 guests