Henk, I would suggest FM 2.4 KHz deviation. You will need a Gaussian filter after the 4800 baud digital to make the logic transitions raised Cosine. The FM modulation needs to be direct coupled not AC coupled. Never Had a TS 2000X still using a ICom 820 disaster!
GMSK provide for a modulation index of 0.5 making its performance a little worse than AM in performance. Works O K on strong signals, looses it on noise, multipath, or interference. There is no capture effect that is normally associated with FM and modulation indexes greater than 1 Good luck, Art, KC6UQH
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Henk, PA3GUO Sent: Wednesday, February 25, 2009 12:21 AM To: amsat-bb@amsat.org Cc: pa3guo@amsat.org Subject: [amsat-bb] Re: GMSK: Time for a stupid question :-)
Thank you to those that replied !
From the feedback I understand that;
- my TS2000X should be in FM mode, connected to the TNC via ACC2 (was indeed the case, thanks for confirming) - my external TNC, the PK-96, should be able to decode GMSK 9k6 (indeed I can decode AO51's downlink)
So...: I will need to team up with someone else in my footprint to see how the Cute digipeater (downlink) can be activated. At this point I have not even heared it, so it can be my ERP (antenna or RF pwr) or the way my PK-96 is generating GMSK 9k6 signals (vs. how Cute expects them).
Thanks so far, I'll certainly share it if I have more success ! Henk, PA3GUO
While trying to work Cute-II, I started to think about GMSK ... (I have a PK96 external TNC hooked-up)
My beautifull TS2000 has FM/AM/USB/LSB/CW modes.
For GMSK, do I use FM or FSK ?
Please only a gentle smile, I realize I do look silly asking this :-) Henk
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