The audio quality of 2M amateur radios is soooo much better than CB and than the little blister pack FRS radios that I've used. Are the GMRS radios that they've got today decent audio quality?
@DaveInDenver My real question is GMRS vs. FRS. I've had those FRS radios in the past and they work OK, but I'm not sure they're any better than a handheld CB radio. Is GMRS a huge step above in quality? I just don't know much about this.
Yes and no.
"Yes" meaning GMRS can equal or even exceed the theoretical fidelity of CB, FRS and even typically ham radio.
"No" in that in the real world handheld and mobile radios are all going to be similar.
FRS being narrowband analog FM (e.g. 12K5F3E and 11K2F3E, see technical stuff below) is pretty close to as good as it can and even a top of the line commercial portable radio using the same channel requirements is going to sound a little thin. Narrowband FM is intentionally about as small of a channel as can be used and still sound OK. Not great but functional.
Broadly speaking portable and mobile radio designers a very long time ago figured out that compressing the audio by cutting off highs and lows and enhancing the mid frequencies make the most effective audio for clarity. So most radios cut off audio below about 300 Hz and above 3KHz anyway. There's no attempt made for
faithful reproduction full frequency spectrum of people's voices. And radios designed for use with tone squelch (e.g. PL tones, CTCSS, repeater tones, etc.) must sharply cut off low frequencies otherwise your voice would upset tone squelch or you'd hear the sub tone.
Further, mics and modulation circuits are designed to punch through and the received audio and speaker is understood to be competing with ambient noise. And that's not to even speak of the impacts doing pre- and de-emphasis will have on quality. You can have a great pre-emphasis but a lousy de-emphasis filter does you no favors. Or vice versa, listening to a bad radio with a good one doesn't magically make it sound good.
Point is ultimately what it really comes down to is the quality of the audio paths are often better, e.g. better mic, filters, audio amps and speaker. A high end CB radio sounds great, like a desktop ham radio with high quality components and a large speaker would.
Two GMRS radios will sound great, like two ham mobiles on simplex. Throw in an FRS radio and it will sound worse. The GMRS radio can communicate with the FRS still but the two-way quality will be dictated by the lower of the two. That's the same as ham. Guys with Yaesu, Kenwood or Icom mobiles sound great to each other but a Baofeng with an external mic is usually pretty obviously on the air.
Technical stuff, just for completeness...
CB is mode 8K0A3E, meaning double sideband, full carrier AM, 8 KHz bandwidth, with a channel spacing of 10 KHz. That means the maximum audio frequency is 4 KHz and there's a guard band between channels.
FRS and the 467 MHz interstitial (stuck between) GMRS channels are required to use 12K5F3E which indicates 12.5 KHz FM, with 2.5 KHz deviation and audio limited to 3.125 KHz on 12.5 KHz channel spacing. Emission mode and spacing suggest there's neither overlap nor guard but technically speaking the occupied bandwidth with audio and deviation limits given should be 11.25 KHz so there's in reality a guard band.
Generally outside of the interstitial channels GMRS is 20K0F3E, 20 KHz bandwidth FM, and 5 KHz deviation and there's a 1 KHz to 20 KHz audio filter requirement with a channel spacing of 25 KHz. This means GMRS has an modulated audio limit of about 5 KHz and will have a guard band between channels.
For 2m ham in Colorado we use 16K0F3E, so 16 KHz bandwidth FM, with 5 KHz deviation. Technically we're limited to 3 KHz maximum audio frequency to stay within the occupied bandwidth of 16 KHz. Since our channel spacing is 15 KHz we have no guard band and actually overlap slightly if hams are using the full 3 KHz on adjacent channels. Utah uses 20 KHz channel spacing and does not overlap channels.