TechMinds: A Look at the TRX DUO Red Pitaya Clone
The Red Pitaya is advertised as an open source electronics laboratory instrument, but as it's essentially a software defined radio with built in computing hardware, custom software can be installed allowing it to function as an HPSDR compatible RX/TX capable SDR.
The TRX DUO is a "Red Pitaya compatible" device that comes at a price significantly lower that the Red Pitaya. Its specifications are comparable to the Red Pitaya SDRlab 122-16 which in the official website goes for 625,00€ / US$622. In comparison the TRX DUO can be found on marketplace sites like Aliexpress for almost half price at US$320.
The TRX-DUO has a tuning range from 10 kHz to 60 MHz, 16-bit ADC and 2-RX and 2-TX channels. It also has a built in ARM Cortex A9 processor, and Xilinx Zynq 7010 FPGA SOC. The built in computing means that decoding software can be run directly on the device if desired.
Matt from the TechMinds YouTube channel has recently tested and reviewed the TRX-DUO in his latest video. His video goes over the specifications, software installation, and a demonstration of it receiving HF signals. He goes on to show how it can be used as an 8-band WSPR monitor, and how you can enable WiFi on it and download various Red Pitaya apps.
Matt also notes that the transmit power of the TRX-DUO is very small at 2.5 mW, but of course an external amplifier can be used to boost this. However, it is important to note that band filtering would be required for the emissions to be safe to transmit.
There is an “open hardware” symbol on the TRX-DUO PCB . So, where can I find the PCB source files?
Are there PCB source files available for RedPitaya PCB?
There is not much information or documentation for the TRX-DUO.
The Red Pitaya is Open Software and not Open Hardware but much information on it including hardware can be found on the website of Red Pitaya Slovenia.
I found some info here: https://elekitsorparts.com/trx-duo-sdr-on-board-connectors-and-ports-guide/
but some of their information is incorrect. For instance this is NOT a 16-bit receiver.
Neither this shop nor the seller via Alibaba have so far answered my questions.
Further investigation into the software has shown that the software used is 14 bit. As long as the Chinese designer of this new equipment is not providing new software, the ADC will run as a 14 bit ADC even though that chip is capable of 16 bits. The software written for the original SDRlab 122.88-16 bit is using a 16-bit FPGA ADC core to handle a 16 bit wide ADC stream. Is this a 16 bit device ? Yes it has a 16 bit ADC chip and no the software handles it as a 14-bit device.
This is not comparable to the SDRlab 16 bit 122.88 MHz version of Red Pitaya. It does not have the 7020 FPGA but a 7010 like the STEMlab 14 bit 125 MHz version. It can not run 16 channels in parallel for wspr or FT8 like the SDRlab. Which can also be seen from Pavel Denim’s image that is loaded as that is the one for the STEMlab. It does look like a nice mix from the SDRlab with its rf coupled 50 Ohm inputs/outputs and the 50% smaller STEMlab.