Next, take apart kerberossdr to see what it looks like inside.
This board should be composed of 4 rtlsdr, there is also a noise source, and a four-in-one usb hub.
This device currently does not have antenna switching, so every time it is calibrated, someone needs to unplug the antenna and replace it with a dummy load and then calibrate it with a noise source, so the antenna and noise source should be connected together. In addition, in order to synchronize the sampling time, 4 rtlsdr should share a clock crystal oscillator. We will see if this is the case later.
Remove the hexagonal screws. This is the side of the Raspberry Pi interface. The blue one is the double-sided tape. The Raspberry Pi interface can theoretically be used to power the Raspberry Pi. In fact, it is not used temporarily. You can see that this side is just There are traces, no components
You can see that there are 2 boards. Lift the bottom to see that the external antenna is connected to the board with an ipex cable.
This board (RF board) is used to combine noise sources and antenna signals. The ANT generated from the main board is directly connected to the external SMA port, and the SDR is connected to several RTLSDRs on the main board.
After unplugging the ipex line of the noise source, you can open the RF board, you can see that there is nothing on the back, and the motherboard is below.
Here comes a close-up of the motherboard.
You can see 4 rtlsdr modules, one of them is circled in the red box. The radio frequency part of the shielding box is the r820t. The white box is rtl2832u. Then they are all gathered on a large chip, which is pink. The USB hub chip in the box, the green box in the lower left corner is the noise generation part, the blue box is the crystal oscillator, and the rtlsdr enable/disable switch in the light blue box, the left side of the yellow box is the usb data, and the right is the power port , The big USB port is useless.
rtlsdr close-up can see that the chip is rtl2832u
Noise generating part and USB HUB close-up
USB hub is smsc usb2517-jzx
