The popularity of software radio (SDR) technology is a heaven sent opportunity for RF enthusiasts. SDR based receivers and transmitters have become so cheap that now you may have one or two sticks on your bench – in fact, we can see three from where we sit.
But the price is low, usually in the form of frequency stability, which may be prohibitive in some applications, especially in amateur radio, spectrum health is the most worrying. Therefore, we are glad to see that [tech minds] solves the problem of SDR frequency stability by using GPS to train the oscillator. The device uses an adalm Pluto SDR transceiver and Leo Bodnar Electronics’ precision oscillator. The oscillator can be programmed to output robust, GPS compliant signals over a wide frequency range. Pluto has an external oscillator input, looking for 40 MHz, which is a good range of gpsdo.
Setting is as simple as inserting the output of the oscillator into the external clock input of the SDR using SMA to UFL jumpers, and adjusting the settings in the SDR and the oscillator. Of course, not all SDRs have external clock input, so your mileage may be different. However, if your equipment is properly equipped, this seems to be a good way to obtain high frequencies – the following video shows how much untrained software radio can drift.
Like any excellent ham, [technology brain] is also doing its part to keep the signal clear and accurate. His main use case will be qo-100, the first geosynchronous satellite transponder of amateur radio. We have to say that hams living in two-thirds of the earth not covered by this satellite are eager to get one (or two) of our own geosynchronous birds to play like this.