At 03:17 PM 7/3/2009, you wrote: >Ok with all the talk of interfacing DV and FM, here is another question.... >if there is an FM repeater, that has no tone whatsoever, what is it about >Dstar that it wont pass through?
Fm repeaters normally use deemphasis and preemphasis, and the audio path may not have an appropriate frequency/phase response to pass GMSK modulation without corruption. However, if you can appropriately link the receiver's discriminator output to the transmitter's modulator, it is possible to pass GMSK, and this will also pass D-STAR. This has actually been done on AO-27, which is essentially an orbiting FM repeater. Obviously, with this setup, you set UR to CQCQCQ, and leave R1 and R2 blank, because the repeater does not decode any of the data. To the D-STAR protocol, the repeater looks like a simplex channel. So, the bottom line is "it depends on the audio path in the repeater". 73 de VK3JED / VK3IRL http://vkradio.com
