On Thu, 14 May 2009 03:02:21 -0000, "Bob" <n3...@aol.com> said:
> I got in full quiet on the K8CLA "K8BIG B" repeater with 1w with this > antenna on the roof of my Caprice Classic in my driveway. I then tried > the same test with the 146.880 and was not able to bring it up. I then > tried it with 5w and did get in with a 5/3 signal report from the same > station I was talking with on the other repeater. > I have reached other repeaters on D-Star with a much better signal and > wish I would have made the jump a few years ago. > > I have to say that from what I have seen a D-Star signal will travel > further than a phone signal, all things being equal. A couple of comments here... you'll see why... "full quieting" is really the only thing you get in digital. With a caveat... see below. I rate D-STAR voice signals this way... you can hear FOUR distinct steps: 1. Audio 100% normal other than the VOCODER loss. Sounds "digital" but perfect. 2. Audio starts to sound "mushy"... what I BELIEVE this is, but can't prove it, is a side-effect of the Forward Error Correction done on all Voice bits in the protocol. You can definitely hear a difference between a "perfect" signal and someone who's "being error corrected", but it's subtle. 3. Garbled to the point where it's been nicknamed "R2D2". The radio can tell there's a signal there but it can't recover enough bits to make the voice intelligible. 4. Gone. :-) It takes a while and you have to be listening for it, usually having one of the mobile rigs with a nice big speaker helps with this in a quiet listening place, but you can pick out the Stage I to Stage II by ear and if you start to learn the coverage of your local repeaters, you can tell when someone's "starting to fall out" and whether or not they're doing it "too soon" for the area they're in... thus, their antenna system is wimpy or they need to go to high power, etc. Where Stage I to Stage II REALLY shows up is on low-speed data. Since there's no FEC on low-speed data, a couple of PC's and radios, and you can VERY accurately "map" your repeater's coverage areas by sending data from a mobile station to a fixed solid signal station. It's one way to get a "baseline" for repeater system changes like adding pre-amps, etc... Even just a station listening to the repeater while your GPS added IC-800H or 2820 sends continuous GPS streams, can be used to see where those continuous data streams "fell apart" in a post-analysis session later on. System admins SHOULD be able to tell if their system is degraded in some way simply by watching the raw GPS data from their 2820 users... If anyone's "bored", custom GPS "ping/pong" mapping/tracking software could be done to SPECIFICALLY build coverage maps. I don't have the time, but the underlying technology is there, and would work nicely... have some volunteers running around with it running, feeding data to an always on the air receiver at someone's house... and you'd have a complete coverage map done in short time. Since the low speed data isn't error corrected, you'll know that voice will go FURTHER, but if you work to maximize your low-speed data coverage, you'll also be maximizing voice.. the "ring" around the site for voice will just be further out. For those interested in a challenge to maximize their receiver performance at the repeater site... Nate WY0X -- Nate Duehr n...@natetech.com
