2 ms·

Is this locked to WiFi spectrum, or could the antennas be swappen for whatever frequency band you want to target? Say starlink frequency for tracking or The NO

Is this locked to WiFi spectrum, or could the antennas be swappen for whatever frequency band you want to target? Say starlink frequency for tracking or The NOAA satellites?

gfkclzhzo 2y ago
ESP32 will be just 2.4ghz, and the bandwidth of the antennas will also limit. Totally doable to make a wideband version with different hardware. This is called a phased array, which is common in radar applications (e.g. Aegis cruisers).
- leptons 2y ago
  Espressif has a new dual-band chip that does 2.4ghz and 5ghz wifi. That isn't the subject of this article, but ESP32 is gaining some new wifi capabilities.
  - Jeija 2y ago
    I'm currently experimenting with ESP32-C5 engineering samples provided by Espressif, so hopefully some future ESPARGOS revision will be 5GHz-capable :) But yeah, as far as I can tell, the chip can only extract CSI from WiFi (unless there is some hidden raw I/Q sample debug mode or something).
    - ipdashc 2y ago
      This project is amazing! I know there's some prior art, but I feel like I've never seen anything wifi-related moving so... smoothly? (With that high of an update/sample rate, I guess?) as your visualizations do. I do have one question that wasn't quite clear to me, in case you happen to see this. There's a bunch of mentions of Channel State Information, but Google doesn't give a ton of info on it. So I'm just wondering, is CSI a "client-side" thing provided by the ESP32 for any Wi-Fi connection, or is it some special protocol feature that the AP or client have to enable?
      - Jeija 2y ago
        Most wireless standards transmit some kind of pilot sequence next to the payload. A pilot is a sequence that is well-known to both TX and RX, and which allows the receiver to estimate the effect that the propagation has on the signal. The channel estimate is then used for equalization, i.e. undoing the channel effect. For WiFi, some of the pilot symbols are called L-LTF (802.11g+n) and HT-LTF (802.11n). Every packet contains them as they are needed for successful communication. The ESP32 can provide channel estimates based on L-LTF and HT-LTF for any packet it receives. No need to enable anything, you can get CSI from every packet.
        ipdashc 2y ago
        Awesome! Thanks for the clarification.
jhart99 2y ago
While the esp32 is only going to be able to do 2.4 GHz. KrakenSDR can be used in a similar way to do spatial mapping of other frequencies. There was a passive RADAR project for it as well that I think was taken down because of ITAR. https://www.krakenrf.com/ https://www.krakenrf.com/

Is this locked to WiFi spectrum, or could the antennas be swappen for whatever frequency band you want to target? Say starlink frequency for tracking or The NOAA satellites?

gfkclzhzo 2y ago

ESP32 will be just 2.4ghz, and the bandwidth of the antennas will also limit. Totally doable to make a wideband version with different hardware. This is called a phased array, which is common in radar applications (e.g. Aegis cruisers).

leptons 2y ago
Espressif has a new dual-band chip that does 2.4ghz and 5ghz wifi. That isn't the subject of this article, but ESP32 is gaining some new wifi capabilities.
- Jeija 2y ago
  I'm currently experimenting with ESP32-C5 engineering samples provided by Espressif, so hopefully some future ESPARGOS revision will be 5GHz-capable :) But yeah, as far as I can tell, the chip can only extract CSI from WiFi (unless there is some hidden raw I/Q sample debug mode or something).
  - ipdashc 2y ago
    This project is amazing! I know there's some prior art, but I feel like I've never seen anything wifi-related moving so... smoothly? (With that high of an update/sample rate, I guess?) as your visualizations do. I do have one question that wasn't quite clear to me, in case you happen to see this. There's a bunch of mentions of Channel State Information, but Google doesn't give a ton of info on it. So I'm just wondering, is CSI a "client-side" thing provided by the ESP32 for any Wi-Fi connection, or is it some special protocol feature that the AP or client have to enable?
    - Jeija 2y ago
      Most wireless standards transmit some kind of pilot sequence next to the payload. A pilot is a sequence that is well-known to both TX and RX, and which allows the receiver to estimate the effect that the propagation has on the signal. The channel estimate is then used for equalization, i.e. undoing the channel effect. For WiFi, some of the pilot symbols are called L-LTF (802.11g+n) and HT-LTF (802.11n). Every packet contains them as they are needed for successful communication. The ESP32 can provide channel estimates based on L-LTF and HT-LTF for any packet it receives. No need to enable anything, you can get CSI from every packet.
      - ipdashc 2y ago
        Awesome! Thanks for the clarification.

jhart99 2y ago

While the esp32 is only going to be able to do 2.4 GHz. KrakenSDR can be used in a similar way to do spatial mapping of other frequencies. There was a passive RADAR project for it as well that I think was taken down because of ITAR. https://www.krakenrf.com/ https://www.krakenrf.com/