A phase compensation algorithm is used to compensate for the additional phase delay introduced by the multiplexed ADC, thereby producing an effect equivalent to a synchronously sampled ADC.
The complete PCB related files are open source, and there is also a design document for reference and study.
This design uses the variable gain wideband amplifier VCA810 to increase the gain and expand the AGC control range, and uses software compensation to reduce the step interval of the gain adjustment and improve the accuracy. The input part uses a high-speed voltage feedback op amp 0 P A842 as a follower to increase the input impedance, and a protection circuit is added to the input part without affecting performance. Various anti-interference measures are used to reduce noise and suppress high-frequency self-excitation. The power output part is made of discrete components. The passband of the entire system is 4.4 k Hz ~ 8.4 MH z, with a minimum gain of 0 dB and a maximum gain of 70 dB. The gain step is ld B/6dB/arbitrarily set. The error between the preset gain and the actual gain below 60 dB is less than 0.2 dB. The effective value of the undistorted output voltage reaches 10.1 V, and the AGC control range is 52 dB when outputting 4.5 ~ 5.5 V.
The Raspberry Pi microcontroller itself does not have an Ethernet MAC, but it can be easily implemented through the programmable IO of the Raspberry Pi. The programmable PIO of the Raspberry Pi microcontroller that costs 5 yuan a piece is indeed a miracle, with IO below 250MHz. Control everything.
Filter circuit (various design solutions + schematic diagram)
51 microcontroller to RTL8019 Ethernet control example (original program + schematic diagram).
UDP test based on STM32 and network chip W5200
The network card driver and LWIP protocol transplant program source code for the Ethernet communication module based on LPC2138 and DM9000AE written by myself.
The physical layer data sending and receiving of a PC is very simple. As long as one condition is met, that is, the CRC check of the data packet is correct, the network card can send the data packet to the application software. Otherwise, the network card will directly discard the data packet, which cannot be caught by any software. to the data packet.
FreeEEG32 is a stackable, open source, 32-channel, 24-bit, sigma-delta, simultaneous sampling board designed to meet the needs of scientists and brain hackers who require high-quality, affordable research-grade equipment. We have been developing this EEG for many years as we worked to create the ultimate open source solution to expensive proprietary EEG technology. FreeEEG32 combines four 8-channel AD7771 ADCs with ultra-low noise (<0.22 μV measured) sources and references, all driven by the powerful STM32H7 ARM Cortex-M7, while handling pre-processing. It's sensitive enough to handle high-quality EEG data collection and more.
Might not be an actual working transmitter, but it does produce a few mW of RF power at 4 MHz using only two LMC555s.
Principle of Operation (see attached simplified schematic):
At lower operating voltages, the flip-flop (TR) input of the LMC555 can be used as an inverting comparator input to control the output of the device. This requires the Threshold (TH) input to be active (high). This circuit applies a DC bias at the switching threshold of TR and superimposes a small AC feedback signal to create an oscillator. An inverted version of the same signal is applied to the second LMC555 to produce two complementary open collector outputs (the device's discharge output). The output is then connected as a standard push-pull RF amplifier. The TH input is used as the enable input to key the transmitter.
Through this open source tool, everyone can better understand how program firmware is "exploded", thereby improving product security. Crack AES, crack RSA, crack DES and so on.
4 Layers PCB 60 x 171 mm FR-4, 1.6 mm, 1, HASL lead free, Green Solder Mask, White silkscreen;10.5GHz, 8 element, patch antenna. Make your own phased array for communications or radar. Full instructions at github .com/jonkraft
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