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ENG-CANSAT-FREQUENCY-PLAN (voir la source)
Version du 20 octobre 2021 à 21:17
, 20 octobre 2021 à 21:17→Frequency plan explained
Why do we space the frequencies of 0.1 MHz (so 100 KHz)? Spacing more (>100 KHz) will be best, spacing less (<100 KHz) is not recommended.
Why do we space the frequencies of 0.1 MHz (so 100 KHz)? Spacing more (>100 KHz) will be best, spacing less (<100 KHz) is not recommended.
The following capture coming from USA shows the spectrum view (and waterfall view) of a RFM69 emiting on the 868.0 MHz frequency. Just remember that
The following capture coming from USA shows the spectrum view (and waterfall view) of a RFM69 emiting on the 868.0 MHz frequency. Just remember that it works the same for CanSat around the 433 Mhz.
{{ambox|text=Note: the 868.0 Mhz is a FREE ISM band in USA. In Europe, that frequency range is reserved for LoRa transmission!}}
{{ambox|text=Note: the 868.0 Mhz is a FREE ISM band in USA. In Europe, that frequency range is reserved for LoRa transmission!}}
{{ambox|text=The carrier wavelength doesn't ship any data/information (no peak in that position) since the "Double Side Bands" are enough to rebuild the transmited information.}}
{{ambox|text=The carrier wavelength doesn't ship any data/information (no peak in that position) since the "Double Side Bands" are enough to rebuild the transmited information.}}
By comparing the spectrum and waterfall (on the right part), we can see the communication take places between 868.0 MHz and 868.030 MHz. This is the same on the opposite side of the picture.
So RFM69 Packet radio transmission takes place between:
* Carrier WaveLength + 30 KHz
* Carrier WaveLength - 30 KHz
So a total of 60 KHz around the carrier Wave length.
{{ambox|text=the waterfall section does show some activities over 30 KHz which is flooded inside the noise (no real peak visible on the spectrum).}}
{{ENG-CANSAT-TRAILER}}
{{ENG-CANSAT-TRAILER}}