Answers below.
From: dstar_digital@yahoogroups.com [mailto:dstar_digi...@yahoogroups.com] On Behalf Of Bill Powell Sent: Wednesday, March 25, 2009 12:11 AM To: dstar_digital@yahoogroups.com Subject: [DSTAR_DIGITAL] Re: Coordinating DD mode "repeaters" Scott and Group, As VP Coordination for the ARCC I have been asked by a number of our users to consider establishing a STRICTLY VOLUNTARY coordination program for DD and other digital "non-repeater" modes. All coordination is "voluntary", Bill. :-) - Can a DD channel be shared in the same manner as an AX.25 system? Likely to degrade rapidly. Proper use of callsigns by users would make it technically POSSIBLE, but problematic. Until 1.2 GHz is "full" it's probably better to spread them out. - Does DD perform CMSA or is it a "blind" system? If it's like other D-STAR implementations by Icom, it can only "hear" D-STAR. So it would probably not transmit if other D-STAR signals are present, but would jump right on top of an analog or other signal "sharing" the frequency. Ultimately someone would have to go test this, or get an answer from Icom on it. - Does DD operate on a single channel or can it be operated on a "split" (pair) of channels? How is it "normally" used? Single channel. Very wide. - What is the definition of "interference" in a DD system? The same as any system, something that keeps communications from occurring! (GRIN) - What is the result of "interference"? Packet loss. The system behaves like a wireless access point, if that helps. - What level of interference is "tolerable" Personally I find the whole system would be mathematically too slow to use beyond 5 local users anyway at 128 Kb/s -- so my personal opinion would be "any interference" would render the system even slower, and "unusable" in most cases. - What is the "true" (measured) receiver sensitivity for a DD central station and at what BER? Good luck getting this from the manufacturer, let alone the Amateurs that own the systems. Nate WY0X [Non-text portions of this message have been removed]
