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

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).

Check with your local radio authority. This is very much country-dependent on the local laws and whatever licenses you hold.

Just because certain bands are open for use in certain countries does not mean that they are not without restriction on duty cycle, modulation modes, power output, antenna gain and bandwidth just to name a few parameters.

E.g. 433MHz is a LIPD band class license for low-power devices (e.g. wireless headphones, garage door openers, etc). But operating 433MHz LoRa may not be legal because of the way it occupies the spectrum and the time (at the moment, there is no clear guidance). But if you possess an Amateur Radio license and you operate under Amateur Radio rules, the 433MHz band is part of the 70cm band and you can operate different bandwidths, modes and powers much higher than LIPD would allow.

Getting this wrong could leave you liable to fines and equipment confiscation (in most countries) especially if you cause interference to others, especially licensed services.

- Gough

Hi shabaz 

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 Gough Lui  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?

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

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.

TL:DR;

The software or firmware in the gateway handles the frequency channels to use with variations per location/Country. For example, there could be a fw version for 868 MHZ where all the band is free or a version for 868_india. As yours is a single-channel gateway, you can work in the 865-867 range.

More Details:

As shabaz  mentioned, the designation "868" or "915" includes some Mhz around that central frecuency. These are proposed as license-free band, however some countries already use those bands full or in part. That's why a combination of channels and bandwidths within the band can be used for LoRaWAN, but that will be very specific to the country radio regulations. I have seen gateway Fw versions like 915_AU, 915_SG, 915_CO for Australia, Singapore and Colombia, respectively. This for multichannel gateways, though.

Yes that's precise information you have mentioned.

So for this module there is a document which mentions how to set a frequence but it does not cover the detail which frequency will work/not work...

So, I can do two things. First ask Dragino weather frequency in range of 865-867MhZ is possible to set and then if not ask local regulatory body for guidance.

The document also mentions how to connect to the TTN.

www.dragino.com/.../LoRa_GPS_HAT_UserManual_v1.0.pdf

There are different versions of these HaTs. I have the one with 868MhZ. As the following image tells us that best tune frequency 868 mhz but it can work anywhere between 862-1020mhz.

So first, I will ask Dragino that if I set the frequency in the range between 865-867 mhz(free in India), then it will only work in that frequency and not cross the min/max limits?

Then perhaps ask the local regulatory regarding how to proceed.?

I guess you can set "freq" and "freq_2" to something between 865400000 and 866800000

It's license free since 2021. 

The use of low power equipment in the frequency band 865-868 MHz for short range devices_Exemption from License_Rules, 2021 | Department of Telecommunications | Ministry of Communication | Government of India (dot.gov.in)