This project is a series of two 10 GHz transceivers that utilize the dual transceiver capabilities of the RFIC in two different ways to build 10 GHz transverters. The foundational concept is to use one of the RFIC transceivers for the IF function and use the second RFIC transceiver function as the LO for the 10 GHz mixer. The first project to be presented utilizes a dual transceiver approach for a ~1.3 GHz LO with suitable harmonic multipliers to ~9 GHz, and a 1.3+ IF transceiver to mix for 10 GHz operation. The second project utilizes the 5 GHz native tuning range of the RFIC transceivers to provide direct IF and LO input to a microwave mixer for 10 GHz operation. This later approach had it’s inspiration from Matt Reilly, KB1VC: SoDa Radio . By capitalizing on the dual transceiver approach, the same high quality, low phase noise synthesizer in the RFIC is used in both the IF and LO. The result is to consolidate the IF and LO connections to a transverter into a single SDR package.
The dual transceiver approach with split frequencies is simple to explain. Review of an advanced SDR block diagram that shows the RFIC analog front end followed by the FPGA and the data stream outputting to the data interface.
The synthesizer implemented within the AD 9361 dual transceiver RFIC controls both transceivers and directs them to the same frequency. For split frequency operation, the FPGA Numerically Controlled Oscillator (NCO) for each channel is programmed in the flowgraph to offset the frequency of operation of each transceiver. The frequency offset potential is determined by the FPGA clock frequency. The offset frequency between the two transceivers is limited to1/2 of the clock frequency each side of the center synthesizer frequency. The Ettus B210, with it’s 32 MHz clock, puts an upper limit of +/-15 MHz offset for each transceiver.
Examining the front panels of the VHF / Microwave SDR and 10 GHz transverter illustrates how dual transceiver approach works in practice. The photo shows two enclosures stacked on one another. The bottom enclosure houses the VHF / Microwave SDR with the RF interface and assorted peripherals such as the CW keyer, beacon keyer, sequencer, and internal 10 MHz precision OCXO. The upper enclosure houses the 10 GHz transverter.
The the front panel of the SDR is divided in the middle by the microwave T/R relay. To the left of the relay are the transmitter and receiver ports for transceiver “A”. To the right of the relay are the transmitter and receiver ports for transceiver “B”. Tracing the coaxial cables from the SDR you can see that the transmitter output from transceiver “A” connects to the TX port of the T/R relay. The receiver input for transceiver “A” connects with hard-line to the RX port of the T/R relay. The “Ant” port of the T/R relay connects via a blue colored coaxial cable to the “IF” connector on the transverter. The transmitter output of transceiver “B”, (the LO signal to the mixer) connects via a blue colored coaxial cable to the LO input port on the transverter. The result is that transceiver “A” of the SDR functions as the IF through the T/R relay. The transmitter portion of transceiver “B” supplies the LO for the transverter. The receiver portion of transceiver “B” is not used in this particular application.
The GNU Radio flowgraph for this project is best reviewed by downloading and executing the .grc file. With that approach you can easily view the entire flowgraph and examine the DSP block parameters in detail. The .grc file for this version of the 10 GHz station can be downloaded here: 10 GHz Dual Transceiver SDR,1.3 GHz IF and LO
A second project utilizes the dual transceiver RFIC option configured for separate 5 GHz IF and 5 GHz LO signals. The IF and LO frequencies, separated by 30 MHz, drive a mixer for 10 GHz operation. The photo of this bare bones mixing system illustrates the interconnections that link the VHF / Microwave SDR and the mixer. The T/R relay IF “ANT” port connects transceiver “A” to the mixer IF port. The transmitter output from transceiver “B” connects to the mixer LO port. The mixer RF port connects via a bandpass filter to the 10 GHz horn antenna.
The GNU Radio flowgraph for this second project is also best reviewed by downloading and executing the .grc file. With this approach you can easily view the entire flowgraph and examine the DSP block parameters in detail. The .grc file for this second version of the 10 GHz station can be downloaded here: 10 GHz Dual Transceiver SDR, 5 GHz IF and LO