Saying D-STAR IS plain FM is even worse than calling PM, FM. There's a difference, a very big difference. FM=Frequency Modulation. D-STAR <> Frequency Modulated, no way, no how.
Can a FM transmitter send a GMSK signal? Well, a FM transmitter can be modified to do so, but then it really isn't an FM transmitter anymore. Normal FM transmitters often have all sorts of audio shaping to optimize transmission. I can send an AM signal and you can receive it on a SSB receiver. I can even send a SSB signal and with a little hocus pocus, (like inserting a carrier) you can receive it on a AM receiver. I can send CW by modulating a tone on a AM transmitter, and it often can look and act pretty close to a CW signal, but it isn't one. I still haven't seen in the pages of QST or any other magazine where I can buy a repeater from anyone besides Icom. If these other alternatives are so much better, then why isn't someone making a lot of money on them? Ed WA4YIH From: [email protected] [mailto:[email protected]] On Behalf Of Neil Sent: Friday, July 03, 2009 2:29 PM To: [email protected] Subject: [DSTAR_DIGITAL] Re: more DV / FM questions Hi John, Well, D-Star IS plain FM, you buy an FM transceiver and the add on board just utilises that for the GMSK data, like packet or any other data mode for that matter. Yes, I agree that the bandwidth is full scale all the time, but measure it on a scope and see that the GMSK data is the same from any source from something purchased and 'home brew'. The SN ratio in my operational tests from GB7AD/CD, near to WE are in my opinion much worse than WE in overall tests, where AD/CD are marginal signals, the drop outs are far far more obvious and noticeable, whereas WE/WB seem to work much further into the noise than what the Icom boxes by design actually achieve. In the Bristol area of the UK, we are really lucky to have one mans work, seemingly do more than what Icom have put into place as a simple 'repeater' with connectivity, at the loss of a far better useable option from SZM's hard work, effort and understanding of how and why the signals deteriorate and loose data so frequently. If you could actually try the Icom and 'home brew' repeaters side by side, you would appreciate the difference and see what I feel to be something that would make D-Star (in the UK in most instances) something worth going for and better overall, even though everyone is using an Icom radio into the nodes in every case! I'm not knocking Icoms achievement in any way here, we do have some wonderful and really good 'nodes' over here, but the simple by comparison efforts by Andy, in my opinion, really do knock the spots off what is available to buy and use, 'out of the box'. If more would just 'try', modify some ex-LMR/PMR gear, (better SN, image rejection, etc etc) I dare say a lot more people would see the benefits from doing this, to compliment the already existing superb network we already have. OK, the Satoshi node adaptor did have its problems, SZM made a workaround for this, it is now stable and seems to keep everything 'alive' after the mod. The pictures on the WE site show the mod and hopefully anyone else experiencing hang-ups should follow the diagram for the 'mod' and implement it whenever they can. Keep up the good work everyone and happy experimenting! 73 De Neil, G7EBY. [Non-text portions of this message have been removed]
