At 02:18 AM 7/10/2009, you wrote: >In a disaster, a basic D-STAR repeater can be just as reliable as a FM >repeater. The gateway is not required for operation. So as long as the >repeater continues to work, it provides the same capabilities that an FM >repeater would, PLUS. The PLUS is the ability to send slow speed data and >voice over the same links, even at the same time. So it actually combines >the functionality of a packet node and FM repeater in one package. And even >if the repeater dies, this same capability exists on simplex.
D-STAR, compared to an equivalent analog system (e.g. comparing standalone repeaters to FM repeaters, and simplex to simplex), offers both the low speed data services (for text, imaging, small file transfer, messaging), and increased range, compared to FM. All in all, it's a pretty compelling package, when you look at it objectively. All D-STAR needs now is: 1. More people to buy radios and other equipment. The more gear out there, the more people there are to talk to. 2. Other manufacturers to jump on board and sell radios. The hams are doing well, with a lot of innovation. It's the established manufacturers (other than Icom) who are dragging the chain. Unfortunately, some hams are waiting for their favourite manufacturer to start selling D-STAR gear. 3. Other alternatives for repeater/gateway systems. This is already well on the way to becoming a reality. >-->Same as FM - sounds like you have swallowed the blue pill from Icom. Our >'terrain' includes very few locations that are line of sight to the site. >We have a VHF Dstar repeater with a 6dB antenna, and 1000' horizontally away >a VHF analog repeater with 6dB antenna. Hands down, absolutely no question, >tested it for months, the Dstar is usable for reliable (non-garbled >communications) for mobiles about 10% or less of the coverage area of the >Analog FM and for base stations about 80%. This is largely due to the >picket fencing of a mobile signal, multipath for non line of sight, etc. On >a high peak in the desert with line of sight, I can see them being >comparable, but not in the real world of trees and buildings. Well, tests done here have seen 120 mile and longer paths achieved on D-STAR, that were not possible on FM. The test repeater at that site would literally allow a QSO between stations over 200 miles apart. This is _demonstrated_ performance. Keep in mind that there are no such things as 10000' mountains down here (highest in the country is a little over 7200'), best you'll get is around half of that for a repeater site (and this particular mountain was probably nearer 3000'). On VHF, the D-STAR repeater on the other side of town is much easier to access than the 2m FM repeaters in the same area. Best range is (obviously) while stationary, but mobile performance here has been on a par with FM. I personally have heard good signals over paths I know I was not able to work on FM, without taking extreme measures, such as using a band that handled the terrain better (i.e. using 6m instead of 2m to get over a mountain in the way). Our experience here is that mobile coverage quite variable compared to FM (sometimes better, sometimes worse - suspect it's dependent on how much flutter there is), base station coverage significantly exceeds that of FM. Looks like we're in markedly different environments to get such different results. >-->Hmmm..you do get NOAA weather alerts over your D-Star repeater? We do on >analog. You get site telemetry (battery voltage, VSWR, etc.) over your >D-star? We do with analog. You have remote control of any of the site I don't see why D-STAR couldn't do those things. Someone has to write the apps to do this, just like someone had to write the code that allows your FM repeater to "speak" this telemetry. >features like turning the power down, switching to the backup antenna, >manually starting the generator, etc on your D-Star repeater? We do with >analog. And guess what, with data on a separate network, I can send and >receive email at the same time I'm listening to the emergency net without >having to occupy their channel for data. Good point about having a separate data network. Sometimes it is best to separate voice and data networks. >(except what Dan has done with Drats which is awesome!). My tool box >includes both, todate the analog side get's 99% of the usage because it >meets the need even if the internet backbone is down. This is the key point. Add D-STAR to the toolbox, but certainly don't dump the traditional FM and packet capabilities. All of those tools will come in handy at times. Me? I'll use whatever gets the job done. In one public service comms exercise many years ago, that literally meant getting up and running with an urgent message to deliver it to the recipient, as I was the closest radio point, and I could see the person the message was meant for about 200 yards away. That leg took well under a minute (I am naturally a sprinter ;) ). At the time, there were just 2 radio ops (1 HF, 1 VHF), and no one else nearby, so I worked out I was about the quickest means to get the message delivered, and the other guy could cover the 2 radios for the time it took me to make the return trip. :) And in case anyone was wondering, yes, this message did pertain to a possible life and death situation, hence the urgency. And a footnote, add physical fitness to your list of EMCOMM tools. :D 73 de VK3JED / VK3IRL http://vkradio.com
