On 30/12/15 22:24, Marcus Müller wrote: > Hi Daniel, > Cannot stress this enough: > Don't try to do everything to the max right from the start. Sure, 100mW > is a lot less than what can do in the licensed bands, but then again, > not coming from an amateur background, 120W right out scare me. Please > make sure no more than -15dBm are fed into the USRP RX. So at an output > power of 120 W ~= 51dBm, you need isolation of at least 66dB between > your TX antenna and the RX port of your USRP for the TX frequency. Also, > considering you're buying a device that can potentially cover 70MHz to > 6GHz, spending lots of money on a powerful amplifier that can but > operate on a few MHz really sounds like an unbalanced investment. Maybe > reduce the output power (unless you want to do moon bounce, maybe), and > get separate filters, just to keep the option of not operating in > 144-147MHz; your whole operational range is much smaller than the amount > of spectrum you can control with the USRP at once. > > Of you're not going to use two highly directive antennas for RX and TX > to achieve isolation: > You will either need an RX/TX switch (that you should definitely control > using the USRPs GPIO pins, which can be programmed to certain states > when transmitting, receiving or doing full duplex) to isolate RX from TX > when transmitting, or an extremely expensive circulator-based device. >
As this isn't specific to ham radio, I created a dedicated page about transceivers on the wiki, including some of your feedback: https://gnuradio.org/redmine/projects/gnuradio/wiki/HardwareTransceiver Can anybody else add more specific examples of RX/TX switches they have used, cases and heatsinks for putting everything together, etc? _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
