Lscott

Maybe for Part 95, but I doubt it for Part 97. I'm waiting to see if the FCC might move to allowing digital voice on GMRS. Yeah, some hate the idea, but it happening now more or less unofficially. If the practice becomes more wide spread the FCC will do another FRS thing where FRS users failed to get GMRS licenses when using those combo radios sold at the time. They'll just throw in the towel and make it official, with some level of regulation, so they won't have to deal with the enforcement issue.

You're not alone. I've read similar comments over time.

I'm sure if it was possible that's what would have been done. Some of the comments I've read said the DVSI code was selected also due to it's low bandwidth requirements, a feature of the algorithm used. That allowed decent sound quality in the allowed bandwidth. At the time some felt it wasn't possible even using digital methods. The simple version of DVSI's algorithm involved a quick analysis of a snapshot of a small time slice of the audio. The resulting info was used to derive variables that were then transmitted. Those variables then were inserted in an algorithm that "simulated" the human vocal track as a filter for multiple sine wave and noise sources. The output of the filter is a simulation of original human speech. That's why it sounds a bit weird because its NOT a compressed direct digital conversion of the original voice. One of the main complaints is the simulated speech lacks some of the subtle nuances of the original speaker, thus for some people making it difficult to tell who it is they are hearing, even though the speech is very readable. One other problem is the algorithm is highly optimize for human speech ONLY. Back ground sounds, like wind noise, sirens etc confuse the crap out of the the process. I was reading a long thread on another forum years back where firefighters were VERY concerned about this. The radio manufactures had to implement various solutions in their radio's audio path to mitigate those issues. Some did a better job that others. This likely accounts for the comments where people claim some digital modes sound better even though they use the SAME EXACT codec. The sound quality likely even varies between manufactures using the same digital voice mode and codec. Also don't forget that modes like DMR uses time slicing, i.e. TDMA slots, so the number of available bits that could be used for improved sound quality are missing verses a mode like P25 which has a higher bit rate I believe. Each digital mode has a fairly complex signaling scheme for communications, which of course consumes bits which could be used for better sound quality by transmitting more parameters to be used in the voice reconstruction process. Some of those bits are used for error correction. Also when Motorola grafted encryption on to MotoTrbo they had to use some of the error correction bits for the encryption info. Some have noticed when DMR enhanced encryption is used the voice quality can degrade a bit. One can really go down the rabbit hole on this topic. It's not as simple as it first appears.

Unfortunately just about everyone uses some form of a digital voice encoder. The leading favorite is the AMBE, previously IMBE, by DVSI. Their proprietary codec is based on early work done at MIT. The link below is a short description from DVSI, which doesn't really revel much. https://www.dvsinc.com/papers/iambe.html A much more in-depth description can be found here from a report published by MIT for the US Air Force in 1987. https://apps.dtic.mil/sti/tr/pdf/ADA181146.pdf My understanding is when the FCC forced the commercial radio services to move to narrow band FM, which was done by reducing the FM deviation, also resulted in a reduction in the signal to noise ratio I believe. At a 12.5KHz bandwidth it's not severe, however at narrower bandwidths it is. The FCC stated at one point they intend to move to a true 6.25 KHz per voice channel width. That's why the major radio manufactures introduced various digital voice technologies. For the moment the FCC seems to be OK with various digital voice technologies that can achieve an "equivalent" voice channel width of 6.25 KHz, example DMR 2 slots in a 12.5 KHz channel. However at some point they may force a move to a true 6.25 KHz channel width, but no official date has been given. This is stated in chapter 1 of the FCC's narrow banding guide. https://transition.fcc.gov/pshs/docs/clearinghouse/guidelines/Narrowbanding_Booklet.pdf In the mean time there are ways to license a true 6.25 KHz channel per the FCC. See attached paper. Splitting 6.25KHz Channels.pdf

Two cans connected by a string still works.

Don’t forget WiFi, Bluetooth and satellite radio/TV.

You can quit using your cellphone. It’s based on wireless two-way radio and digital voice technologies.

With more departments going digital, usually P25 with a few doing NXDN or even DMR, usually on a trunking system, its getting really hard to do. That's where using an SDR comes in handy. But then again you're not going to be TX'ing with an SDR so it's moot. Then there is the issue of encryption using the digital modes. Huge rants about that on "radioreference.com" to the point if you bring it up you can get booted.

You should see some of my other finds. Figuring out where a used radio comes from is part of the fun collecting them. I usually do a read of the radio before reprogramming them for my use. I got one analog radio that apparently was used by the maintenance department at a nuclear power plant out east. That took a while to track down based on some memory tag names, a few lucky guesses and matching frequencies in the radio to what I found on the FCC's database for a particular license holder. Sometimes reading the radio the internal messages make it easy like the below. Usually it takes a lot more effort to figure it out.

Not always. I got a radio from an eBay seller in Canada that was on a trunking system. I used a specially hacked radio programming software to get the info out of the radio without requiring the "system key file" from the trunking site. Some system admin claimed it wasn't possible without the key file. Oops.

Ah, you too. My employee number at work is 666. Don’t know if that’s lucky or not.

My buddy had one of these. He found on-line a code plug hack to get the radio to run on VHF. That did work EXCEPT the harmonics was through the roof on VHF! I heard him fine at work here from our other building. Then for grins I tuned to the third harmonic on the 70cm band. He sounded even louder! Oops. Likely a result of the deviation being 3 times what it was on VHF. He quit using the radio, at least not with the code plug hack for VHF.

Isn't that called a "smart phone" with an Internet connection?

Maybe not any more. https://www.whitehouse.gov/presidential-actions/2025/03/designating-english-as-the-official-language-of-the-united-states/