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Fast OOK demodulation with SX127x

Semtech Transceivers SX127x family
#1

Hi all,
the datasheet e.g. of the 1272 lists 32.768 kbps as max. frequency for OOK modulation/demodulation. I wonder if faster modes are possible, if not with the internal packet engine, then maybe using the raw mode with external decoder? I am interested in communication with external devices using the ISO/IEC 14543-3-10 (EnOcean) protocol, which uses 125kbps ASK (basically OOK, but without completely shutting of the carrier for the “0” symbol).
Regards,
Stefan

#2

Stefan,

he chip is limited in its ability to switch on and off very fast, and 125 kbps isn’t realistic

Rgds

#3

Hi guys, Do you know about SF(Spreading Factor) on OOK Modulation? Is SF, important factor on OOK modulation? ı I do not see in Datasheet. If anyone know about stuff please help me :slight_smile: I will really appreciated .

#4

Spreading factor is a LoRa modulation and not used in OOK modulation.

1 Like
#5

Thanks buddy, But I am confuse about bandwith. If SF is not important on OOK modulation: Do you mean “do not have Bandwith stuff”. Didn’t I misunderstand?

We use this library , and we could not get data when we change the SF value for example SF=7 to SF=12.

#6

We try to send photo in 433MHz frequency(In a Rocket competition in TURKEY) but we need to Data rate for calculate “In 6000 meter could we send photo, how much time ?” . I reach this calculation(BUT THIS USE IN FSK MODULATION). But there is a problem that we use OOK modulation. WE CAN NOT USE THIS CALCULATION. We need help about data rate calculation in OOK modulation. I am new about LoRA devices. We use RFM98PW (in transmitter side) and RFM98W(in receiver side). In addition, we use Yagi antenna in receiver side and 433MHz RF antenna in Rocket.

DR:Data Rate
SF: Spreading Factor
CR: Coding

DR = SF x BW / 2^SF x CR

You can see the Datasheets:

RFM98PW(In transmitter side)
https://pdf1.alldatasheet.com/datasheet-pdf/view/1139154/HOPE/RFM98PW-433S2.html

RFM98W(In Receiver Side)
https://pdf1.alldatasheet.com/datasheet-pdf/view/750175/ETC2/RFM98W-433S2.html

#7

Its not common for people to use the FSK\OOK part of the SX127x devices and there are not so many libraries that support it.

In any case I would not get too concerned about the ‘calculation’ just do some simple real world transfer tests, that will give you a far better idea of the actual achievable data transfer rate.

1 Like
#8

We was able to communicate in 9km with this devices. But we wanted to understand, “What is the side of bandwith factor in OOK modulation?”. Because when we change the values (Bandwith and SF) in libary, got lost data.

#9

Cant help with that, I have no knowledge of a connection between bandwidth and SF, which are normally LoRa parameters, and OOK mode.

1 Like