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Want to ask about spectrum distribution of radio waves specifically for LoRa application

embeddedguy

Hi Everyone,

I have a Dragino LoRa module HaT which is compatible with RaspberryPi version 3 and older. I wanted to create a LoRa gateway(single channel) for personal use and evaluation how things work.

I saw that the HaT is compatible with frequencies as follows...

868 MHZ/433 MHZ/915 MHZ(Pre-configure in factory)

https://www.dragino.com/products/lora/item/106-lora-gps-hat.html

The region I am living right now(India) does not have 868MhZ as license free band and also not other two remaining frequencies supported by this shield. However here frequencies from 865 to 867MhZ are license free.

These has created confusion to me weather I could use this shield for my application. Some internet discussion also suggest that the module can be configured to 687 MhZ to be used.

Other suggest even that the 868 MhZ can also be used license free as channels are overlapping with 867 MhZ frequency. This has created confusion to me. It would be helpful to ask and get some insight how these frequency division works.?

On internet there are only a few key information but not details about how it distributed.

Parents

  • Hi,

    If you can legally operate at 867 MHz then the board will work at 867 MHz, even though it says 868 MHz on it. That's because 868 is a loose term that actually includes channels at 867 MHz part of the spectrum too.

    You also mentioned 687 MHz. I don't know if you made a typo or not. If you really meant 687 MHz then the answer is no, it won't work at 687 MHz because component values are incorrect for that. It might appear to work over a short range but it won't be optimum.

    You also mention 'LoRa gateway", please be aware that is different from LoRaWAN gateway. The board cannot be used as a LoRaWAN gateway. I'm just mentioning this in case you were looking to implement LoRaWAN (a lot of people get the two terms LoRa and LoRaWAN confused so I just wanted to be sure that when you mentioned LoRa, that that's what you actually wanted).

  • in reply to shabaz

    Hi  

    That was a typo. I meant 867MHz. Well somewhat confusing yet as channel distribution, bandwidth etc are unknown.

    For example in the following website they mention how up link and down link for channels for particular frequency is assigned. Mostly for EU and US region.

    wifivitae.com/.../

    Same should be there for India which perhaps I could look.

    You are right that 868 is a loose term...but as   mentioned in the following reply, there may be a chance for interference to others? Or bad would be that I break a law and get fined?Sweat smile

  • in reply to embeddedguy

    Well, if you refer to The Things Network's LoRaWAN Frequency Plans (https://www.thethingsnetwork.org/docs/lorawan/frequency-plans/), it seems use of LoRaWAN frequencies in India is quite restricted -

    IN865-867
    Uplink:
        865.0625 - SF7BW125 to SF12BW125
        865.4025 - SF7BW125 to SF12BW125
        865.9850 - SF7BW125 to SF12BW125

    Downlink:
        Uplink channels 1-3 (RX1)
        866.550 - SF10BW125 (RX2)

    That's not to say if you run your own LoRa that you can't choose any other frequencies ... but compared to EU868, you can see that the frequencies you can use are very different, so you shouldn't just use an EU868 band-plan and expect to get away with it.

    This Indian-hosted page - https://www.ensembletech.in/lora-frequency-bands-india/ seems to suggest you are allowed to use frequencies in the 865 MHz to 867 MHz license free band. One LoRaWAN bandplan they suggest is:
    0    865.400 MHz    MultiSF 125 kHz
    1    865.600 MHz    MultiSF 125 kHz
    2    865.800 MHz    MultiSF 125 kHz
    3    866.000 MHz    MultiSF 125 kHz
    4    866.200 MHz    MultiSF 125 kHz
    5    866.400 MHz    MultiSF 125 kHz
    6    866.600 MHz    MultiSF 125 kHz
    7    866.800 MHz    MultiSF 125 kHz
    LoRa    865.700 MHz    SF7 250 kHz

    If you're running your own LoRa (i.e. non-LoRaWAN, a single channel private LoRa), then I'd suggest you choose a frequency which makes your whole transmission sit inside the 865-867MHz band. You can perhaps pick any of the ones above and find it works.

    But again, confirm with your local radio agency - they may publish the legal requirements for using license-free bands which you need to comply with. I know the Australian ACMA that governs me (as I'm in AU) publishes this legislation online.

    - Gough

  • in reply to embeddedguy

    Hi,

    That's correct, what you can legally do, and what is technically supported by hardware are two different things. Both need to align so yes, you will need to check your country legislation. 

    No country (as far as I am aware) will excuse you for not knowing any law (not just LoRa frequency related), so you have a duty to check based on your specific country.

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  • in reply to embeddedguy

    Hi,

    That's correct, what you can legally do, and what is technically supported by hardware are two different things. Both need to align so yes, you will need to check your country legislation. 

    No country (as far as I am aware) will excuse you for not knowing any law (not just LoRa frequency related), so you have a duty to check based on your specific country.

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