CIC compensation filters now follow the 2-stage decimating CIC filters for the I-Q-signals. The CIC compensation filters are two identical FIR filters (one filter each for the I signal and an identical filter for the Q signal) with currently 81 taps. They flatten the passbands Read More …
The DFSDM of the STM32H7 or 128 != 16×8 != 8×16 (Part III)
continued from part II: The passband of CIC filters is not flat. This begs the question of whether this behavior should be corrected. In most cases, the CIC is therefore followed by a so-called CIC compensation filter. Zooming into the filter plot of the sinc4/dec.15 Read More …
The DFSDM of the STM32H7 or 128 != 16×8 != 8×16 (Part II)
continued from part I: As explained in part I, the first version of my H7-SDR uses only one CIC filter of the DSFDM for filtering the I-signal and another one for filtering the Q-signal. However, the DSFDM contains 4 filters (see chapter 30 of RM0433 Read More …
The DFSDM of the STM32H7 or 128 != 16×8 != 8×16 (Part I)
My software defined radio for receiving AM transmissions in the 49 m band (see https://dm1cr.de/reception-of-radio-darc-transmission-with-a-microcontroller-only-sdr) looks quite primitive in the first version: It comprises a bandpass filter for anti-aliasing, an STM32H743ZI microcontroller and an audio amplifier with loudspeaker. The ADC inside of the STM32H7 is Read More …
Reception of a Radio-DARC-transmission with a microcontroller-only-SDR
A few moments ago I was able to receive the Radio-DARC-transmission from 11:00 CEST, Sunday, June 13, 2021, with my homebuilt SDR, that just became ready for a first try on the antenna. The received sound was loud and clear. The SDR comprises an anti-aliasing-filter, Read More …
Bandpass sampling and analog bandwidth of the 16-bit ADC peripheral of the STM32H7, Part II
The STM32H7-application sends ADC data to the PC via USART3. Rx and Tx of USART3 are connected to the ST-Link debugger on board of the NUCLEO-STM32H743ZI. The ST-Link driver that gets installed when you install the STM32CubeIDE supplies also a virtual COM port that can Read More …
Bandpass sampling and analog bandwidth of the 16-bit ADC peripheral of the STM32H7, Part I
I have to admit of having had some prejudices about ADCs in microcontrollers.From my experience, they are slow and noisy of no use for really demanding applications.Well, the 16-bit ADC peripheral of the STM32H7 of ST Microelectronics may be a real game-changer. It seems to Read More …
Bandpassfilter für 6070 kHz (Radio DARC)
Wozu braucht man einen Bandpassfilter für 6070 kHz? Wer es noch nicht wissen sollte: Jeden Sonntag von 11h bis 12h sendet der Deutsche Amateur-Radio-Club https://www.darc.de/nachrichten/radio-darc/ über den Sender Moosbrunn https://de.wikipedia.org/wiki/Sender_Moosbrunn auf Kurzwelle bei 6070 kHz (49 m) mit AM-Modulation ein einstündiges Programm aus. Wer dieses Read More …
Tuya smart switch: Tasmotizing mit ESP-M3 CPU-Modul unter der Haube
Beim Durchblättern der Angebote des China-Versands meines Vertrauens fiel mir nicht nur der Sonoff Mini R2 auf, den ich in diesem Beitrag beschrieben habe, sondern auch dieser Tuya Mini Smart Switch, der nach dem Auspacken so aussah: Neugierig geworden, habe ich das Gehäuse vorsichtig geöffnet: Read More …
Feinstaubsensor SPS30 und Tasmota
Hat eine direktere Messung der Aerosolkonzentration zur Abschätzung der Ansteckungsgefahr mit Corona-Viren in Innenräumen Vorteile gegenüber der indirekten Messung über die CO2-Konzentration? Möglicherweise schon: Wenn in einem schlecht belüfteten Raum #1 die Anwesenden gute und dichte FFP2-Masken tragen, dann wird vermutlich die CO2-Konzentration genauso schnell Read More …