Sleeper video of the year so far. All of that was fantastic.
And imagine that, quality content without “be sure to like and subscribe!”.
Broadcasting LoRa packets wihout a radio [video]
21–30 of 36 posts
Re: Broadcasting LoRa packets wihout a radio [video]
#22I really liked the explanation of how he used harmonics to get to the frequency he desired. Also, LoRa is really good when it comes to low power data transmission. To share a recent example, with just ~100mW of transmission power, they managed to fly an RC plane to a distance of 100km: https://www.youtube.com/watch?v=CYJ2UOrlXgM .(Their transmitter from the ground station was configured at a higher power, but the tra…
Doesn't LoRa have a pretty constrained duty cycle? I read the regs on LoRa (for the US at least) and found that you're required to limit transmission frequency to 1% (36s/h). I'm guessing you'd have to go well past that to operate an RC aircraft in the conventional manner. If you're just commanding waypoints I suppose you could be compliant.
IIRC the 1% duty cycle is an EU restriction. The US 915 MHz band has a 400 millisecond dwell time restriction instead.
Re: Broadcasting LoRa packets wihout a radio [video]
#23Earlier quoted context omitted.
100km @ 100mW is not impressive when it's attached to a 30dBi antenna...
Why not?
The amount of "db" to make a link is called the link budget. 20dbm (100mw) + 30db antenna is equivalent to over 300 WATTS out of a 3db standard 1/4 wave monopole antenna (assuming the rx side is equal).
Re: Broadcasting LoRa packets wihout a radio [video]
#24I transmitted this way using a raspberry pi and a basic filter and antenna and was heard one day in New Zealand from Ohio. https://github.com/JamesP6000/WsprryPi
Wow! What were the specifics?
Pretty much that project, a Raspberry Pi, a ham radio license, a small filter board from QRP Labs, an MFJ antenna tuner, and then a long wire over the roof of a single story home. No other amplifier. The New Zealand reception was just once. I did somewhat more often get heard in Germany or Brazil, and quite regularly east of the Mississippi and west of the Appalachians, but never closer than about 50 miles, that is, no one ever heard me in town. This was across like 40 meters and 10 meters I think about seven or eight years ago. I ran the beacon all the time for a couple of years.
Re: Broadcasting LoRa packets wihout a radio [video]
#25I really liked the explanation of how he used harmonics to get to the frequency he desired. Also, LoRa is really good when it comes to low power data transmission. To share a recent example, with just ~100mW of transmission power, they managed to fly an RC plane to a distance of 100km: https://www.youtube.com/watch?v=CYJ2UOrlXgM .(Their transmitter from the ground station was configured at a higher power, but the tra…
Doesn't LoRa have a pretty constrained duty cycle? I read the regs on LoRa (for the US at least) and found that you're required to limit transmission frequency to 1% (36s/h). I'm guessing you'd have to go well past that to operate an RC aircraft in the conventional manner. If you're just commanding waypoints I suppose you could be compliant.
I think if you go to 500khz you can transmit all you want. It's only 125khz that has that limit.
Re: Broadcasting LoRa packets wihout a radio [video]
#26I really liked the explanation of how he used harmonics to get to the frequency he desired. Also, LoRa is really good when it comes to low power data transmission. To share a recent example, with just ~100mW of transmission power, they managed to fly an RC plane to a distance of 100km: https://www.youtube.com/watch?v=CYJ2UOrlXgM .(Their transmitter from the ground station was configured at a higher power, but the tra…
I looked a bit into the LORA protocol. It does offer reception below the noise floor. LORA doesn't do anything to attempt to make other LORA transmissions seem like noise to a receiver that's attempting to lock to your transmission. This makes it possible for a transmission that's closer to the receiver to essentially jam a transmission that's far from it. I guess since LORA isn't used that much, it's not a problem t…
One of the things you can do with Lorawan is use multiple gateways. Interferers
are always an issue for a bunch of reasons.
The worst is when someones on your channel using the same modulation as you are. If he's louder he'll blow your packet out of the water. Keeping your packets short and using max power (cheezy grin) and retrying helps.
But even interferers on different channels will degrade your sensitivity and reduce your range.
None of this is unique to lora modulation.
Re: Broadcasting LoRa packets wihout a radio [video]
#27I transmitted this way using a raspberry pi and a basic filter and antenna and was heard one day in New Zealand from Ohio. https://github.com/JamesP6000/WsprryPi
But then you are transmitting at 0,5 bit / second?
The ideal range/speed is somewhere between 100 and 1000MHz, ideally you would want that entire range.
But how do you build a band pass filter that can cover the entire range?!
Re: Broadcasting LoRa packets wihout a radio [video]
#28So, you thought that machine was airgapped....
i bet this technique has been used for years by the NSA.
Re: Broadcasting LoRa packets wihout a radio [video]
#29So, you thought that machine was airgapped....
i bet this technique has been used for years by the NSA.
Re: Broadcasting LoRa packets wihout a radio [video]
#30I really liked the explanation of how he used harmonics to get to the frequency he desired. Also, LoRa is really good when it comes to low power data transmission. To share a recent example, with just ~100mW of transmission power, they managed to fly an RC plane to a distance of 100km: https://www.youtube.com/watch?v=CYJ2UOrlXgM .(Their transmitter from the ground station was configured at a higher power, but the tra…
Notably, Wez's flight was done with 2.4GHz LoRa (this was one of his main points, to address naysayers who claimed a 2.4GHz link could never achieve >100km) while Charles is using 900MHz - the same setup that achieved 100km (100mW with a lightly directional antenna on one end, ExpressLRS 50Hz RF mode) would have a theoretical range of >500km on 900MHz. LoRa at longer wavelengths can achieve some incredible feats - li…
Yeah.. but with 900Mhz won't there be a lot more interference from 4G towers though?
I remember there were a bunch of "Crossfire failsafed near a 4G tower because i chose the wrong region" videos.