I am loathe to see a 10W PEP transmitter be needed to mitigate poor phase noise in the RX LO's or to mitigate spin modulation induced fades. If we have a spin rate of 6-10 RPM and we use low power and FEC providing time diversity by encoding in blocks, surely the better solution is improve the phase noise performance of the LO's in the receiver and require less peak power on the uplink?
John B. Stephensen wrote:
I was thinking of phase modulation due to the spinning off-center antenna. A wider bandwidth would reduce the effects. The idea has been to have a 90-120 degree beamwidth antenna at 70 cm so that it works well over 75% of the orbit. The last antenna proposal that I saw was a single patch so there shouldn't be much fading on the class 1 uplinks due to the antenna pattern.
Since the access method for class 1 hasn't been decided, another approach to widening the bandwidth would be to use TDMA on one or more uplinks and a higher data rate. Ground station costs proabably don't change much up to 10 W PEP. It would be nice to keep class 1 uplink and downlink bandwidths below 2.5 kHz so that a sound-card modem could be written that works with existing transceivers.
73,
John KD6OZH