Satgen357 Going Digital Pt5 by GM4IHJ 27 Jan 96 Assuming that you have experimented with the Dove downlink on 145.825 Mhz AFSK 1200 bps ( presently sending only short sequences , not full telemetry ). That you have then mastered the much more involved Phase Shift Keyed digital downlinks of A016 and A019. Then and only then, should you venture into the still more involved world of Uo22 and the Koreasats, with their 9600 bps FSK up and downlinks. You can still use the same PB PG or, WiSP protocol software you used with Ao16 PSK , but your hardware must be improved and your operating technique must change. Firstly because, a digital signal being keyed at 9600 bps is almost indistinguishable from noise, you have to tune it via your receiver centre reading FM tuning aid, and because you cannot hear it you will save yourself a lot of sweat and tears , if you connect an oscilloscope permanently to your FSK modem "EYE" diagram terminals. Then at least you will know when the satellite is above your horizon. You can operate with manual tuning if you wish because FSK is much less tuning conscious than PSK, but Auto Frequency control is desirable if you wish to avoid fatigue when operating regularly. You cannot however use off the shelf transceivers /receivers. Almost all amateur radio FM equipment uses digitally unacceptable ,Pre emphasis on transmit and De emphasis on receive. Pay no attention to the digital input/outputs on the backs of some equipment. They may work for PSK but they will not work for wide band FSK. In almost all amateur radio equipment however expensive, you have to go inside and solder direct feeds for your FSK input and output. The transmit connection should be near to but not directly on the varactor , and the receive connection should be fed from the discriminator via a resistor ( Eg R32 10k in FT736 Tx, and R91 on FT736 Rx ). Connections should be made on the end of the resistor remote from the varactor or discriminator. Having brought these mods out to suitable new sockets on the back of the equipment, you are now equiped for 9600 bps FM operation, but please remember that if you want to retain the option of ordinary FM voice operation you must arrange switching which disconnects these additional FSK connections when they are not required or you will corrupt the normal audio response. Equally important disconnect your mike when using FSK. You can go further. Not content with the above modifications some operators have optimised their equipment for FSK 9600 by , in the FT736 removing capacitor C82 .01 uF ( audio shaper ), and/or fitting 20 kHz filters in place of the narrower standard FM filters. This mod is particularly useful because it makes tuning easier , with less retunes being necessary to get good copy with the wider bandwidth response. So at last, having completed at least the essentials in the above catalogue of possible modifications, you finally get to try to access Uo22 and download data. The results can be very satisfying indeed. The data flow is swift ( provided you have ensured your TNC to computer link is set for a speed of transfer well above 9600 bps so that it can handle the demodulated signal and keep ahead of it with no flow problems), and you will enjoy the very useful bang up to date information from this best of all digital modes.