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Bandwidth question


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Posted

Being new to the whole GMRS world, I am trying to understand all the rules and regulations that apply. 

Regarding the allowed bandwidth, I have found the following on the FCC site:

 

§95.1773   GMRS authorized bandwidths.

Each GMRS transmitter type must be designed such that the occupied bandwidth does not exceed the authorized bandwidth for the channels used. Operation of GMRS stations must also be in compliance with these requirements.

(a) Main channels. The authorized bandwidth is 20 kHz for GMRS transmitters operating on any of the 462 MHz main channels (see §95.1763(a)) or any of the 467 MHz main channels (see §95.1763©).

(  Interstitial channels. The authorized bandwidth is 20 kHz for GMRS transmitters operating on any of the 462 MHz interstitial channels (see §95.1763( ) and is 12.5 kHz for GMRS transmitters operating on any of the 467 MHz interstitial channels (see §95.1763(d)).

© Digital data transmissions. Digital data transmissions are limited to the 462 MHz main channels and interstitial channels in the 462 MHz and 467 MHz bands.

 

I have friend that has some older radios he offered to me but he thinks the specks on them say that they are at the old spacing, 25 kHz. Are these radios still allowed to be used in the GMRS service and will they work with GMRS repeaters at this bandwidth? 

 

Thanks in advance for any help. 

4 answers to this question

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Posted

They work fine with GMRS repeaters. If they are Part 95 approved (most Kenwoods, a few Motorolas, maybe some others) they are legal. If they are just Part 90 approved, FCC has stated that they are aware that folks are using them on GMRS.

Fact is, a lot of the repeaters are built from old Part 90 radios.

Clear as mud?

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Posted

Just to add to what RCM mentioned - GMRS was not involved in the FCC Part 90 rebanding plan from a few years ago because it is a Part 95 service - not Part 90.

Therefore 'wideband' operations on the MAIN channels listed in your post, is the normal operating mode for most licensed GMRS operators and for most repeater operations.

 

Welcome to the Forum.

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Posted

I have friend that has some older radios he offered to me but he thinks the specks on them say that they are at the old spacing, 25 kHz. Are these radios still allowed to be used in the GMRS service and will they work with GMRS repeaters at this bandwidth? 

 

Thanks in advance for any help. 

 

 

It is highly likely that those radios are actually 20KHz bandwidth, not 25. You'd have to be looking at radios well over 30 years old to see 25 KHz bandwidth. If the FCC Type Acceptance shows an emission code that is 16Kxxxxxx, it is 20KHz. Given the fuzzy response from the FCC, you may consider legacy 20KHz radios to be very usable in GMRS. I do.

 

The narrowbanding effort that culminated on the the deadline of 1/1/13 brought most of Part 90 down to 12.5KHz, forcing a lot of agencies to remove their older 20KHz only radios from service which is why you see so many of them for sale on auction sites.

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