RFI-EMI-GUY
Member
- Joined
- Dec 22, 2013
- Messages
- 7,378
From time to time someone will post a proposed plan to "fix" GMRS.
This is done with good intentions, but without having or considering all of the facts.
Fix #1: Make more channels available, Narrow Band GMRS.
Fallacy: GMRS already has as many channels available as possible due to the fact that the traditional 12.5 KHz "interstitial channels" were allocated for FRS operations. If you reduce the deviation of GMRS from +/- 5.0 KHz to +/- 2.5 KHz you will have a 3 dB reduction in signal to noise ratio. And you will not gain any channels.
FIX #2: Reduce power for GMRS from 50 watts to 25 watts.
Fallacy: Why? Why would you do this? This will result in an additional 3 dB reduction in signal to noise ratio.
Argument for Fixes 1 and 2: Why not, 6 dB is equivalent to 1 S-unit.. Not much of a reduction
Fallacy: 6 dB means a lot more with respect to area communications reliability.
Look at the differences 3 dB and 6 dB make in the maps on this page. It is very significant
LEIKHIM AND ASSOCIATES LLC - VHF-UHF Narrowbanding
Fix #3; Lets make it license by rule. I don't like paying "the man" $70 for a license and I don't want "the man" to know what and where I am up to.
Fallacy: The $70 is for a 10 year license that is good for you and many of your relatives. It is less than 2 cents per day. By god are you that cheap? If so get into CB or ham radio. "The man" already knows what and where you are up to from your iphone. GMRS actually by its obscurity gives you more freedom.
Fix #4; Lets make GMRS a digital service!
Fallacy; Not so much as a fallacy, there are certain digital technologies that would enhance GMRS. However, the existing "wide band" FM technology has proven to be quite resilient and easy to interoperate between radio models. There are a number of digital technologies proposed. P25 which is very expensive and will not improve spectrum utilization. NXDN which shows promise but is not a huge commercial success. DMR is similar in some aspects to NXDN, but is an international standard adopted by nearly all manufacturers. DMR allows networking via IP and provides 2 slot TDMA. So yes , my bias is toward DMR. But getting there would require a consensus and a strong argument to show the FCC. Don't count on either. Until then enjoy wide band FM as the FM god Major Edwin H. Armstrong intended.
Fix #5: Lets make GMRS an extension of the 70CM ham band that way I can use my ham license and save 2 cents per day.
Fallacy: Amateur radio Part 97 and GMRS Part 95 are totally difference services with totally different goals.
FACTS:
GMRS is the only free relatively unrestricted, communications band that an individual can make use of high performance, 50 watt, wide band commercial grade performance. GMRS permits repeaters. None of the other Personal Radio services allow repeaters.
GMRS band is located in very desirable UHF spectrum. It would not take much to convince the current FCC administration to pave over it with commercial services. By having a license, GMRS operators are showing interest in occupying that space. Make use of it, dont abuse it by operating unlicensed, dont abuse it by running excessive power.
Buy radio equipment that meets the GMRS service specifications. If the transmitter does not modulate +/- 5.0 KHz and have an emission designator of 16K0F3E or 20K0F3E, you are not getting all the performance you can from GMRS. Some vendors repackage FRS junk with a higher power transmitter and call it GMRS. Shop wisely.
Please don't "fix" it.
This is done with good intentions, but without having or considering all of the facts.
Fix #1: Make more channels available, Narrow Band GMRS.
Fallacy: GMRS already has as many channels available as possible due to the fact that the traditional 12.5 KHz "interstitial channels" were allocated for FRS operations. If you reduce the deviation of GMRS from +/- 5.0 KHz to +/- 2.5 KHz you will have a 3 dB reduction in signal to noise ratio. And you will not gain any channels.
FIX #2: Reduce power for GMRS from 50 watts to 25 watts.
Fallacy: Why? Why would you do this? This will result in an additional 3 dB reduction in signal to noise ratio.
Argument for Fixes 1 and 2: Why not, 6 dB is equivalent to 1 S-unit.. Not much of a reduction
Fallacy: 6 dB means a lot more with respect to area communications reliability.
Look at the differences 3 dB and 6 dB make in the maps on this page. It is very significant
LEIKHIM AND ASSOCIATES LLC - VHF-UHF Narrowbanding
Fix #3; Lets make it license by rule. I don't like paying "the man" $70 for a license and I don't want "the man" to know what and where I am up to.
Fallacy: The $70 is for a 10 year license that is good for you and many of your relatives. It is less than 2 cents per day. By god are you that cheap? If so get into CB or ham radio. "The man" already knows what and where you are up to from your iphone. GMRS actually by its obscurity gives you more freedom.
Fix #4; Lets make GMRS a digital service!
Fallacy; Not so much as a fallacy, there are certain digital technologies that would enhance GMRS. However, the existing "wide band" FM technology has proven to be quite resilient and easy to interoperate between radio models. There are a number of digital technologies proposed. P25 which is very expensive and will not improve spectrum utilization. NXDN which shows promise but is not a huge commercial success. DMR is similar in some aspects to NXDN, but is an international standard adopted by nearly all manufacturers. DMR allows networking via IP and provides 2 slot TDMA. So yes , my bias is toward DMR. But getting there would require a consensus and a strong argument to show the FCC. Don't count on either. Until then enjoy wide band FM as the FM god Major Edwin H. Armstrong intended.
Fix #5: Lets make GMRS an extension of the 70CM ham band that way I can use my ham license and save 2 cents per day.
Fallacy: Amateur radio Part 97 and GMRS Part 95 are totally difference services with totally different goals.
FACTS:
GMRS is the only free relatively unrestricted, communications band that an individual can make use of high performance, 50 watt, wide band commercial grade performance. GMRS permits repeaters. None of the other Personal Radio services allow repeaters.
GMRS band is located in very desirable UHF spectrum. It would not take much to convince the current FCC administration to pave over it with commercial services. By having a license, GMRS operators are showing interest in occupying that space. Make use of it, dont abuse it by operating unlicensed, dont abuse it by running excessive power.
Buy radio equipment that meets the GMRS service specifications. If the transmitter does not modulate +/- 5.0 KHz and have an emission designator of 16K0F3E or 20K0F3E, you are not getting all the performance you can from GMRS. Some vendors repackage FRS junk with a higher power transmitter and call it GMRS. Shop wisely.
Please don't "fix" it.
Last edited: