A 1 km, or even 1.8km range, seems enough to satisfy most people and it’s impressive. But what if I wanted more, say 3km? What if I wanted to circumnavigate an obstacle, like a 50m hill between Tx and Rx? Can I put a PA on the Tx output? Or an LNA on the Rox input. Or both. Any design ideas? Let’s pretend that I’m not limited by regulations. Can I transmit at a lower frequency? I am nowhere near capable of designing RF circuitry so I’d want to buy an off the shelf module, like an HC-12, not attemp my own.
I’m actually trying to solve a real problem. Is a relay/repeater a possible solution? I’ve searched and found nothing in this area. No repeater info, PAs, frequency agility etc. Any help will be gratefully received.
Absolutely agree that regulatory restrictions are in place for good reason and I don’t/won’t trample on them. The specific application is geographically isolated from any other user of the spectrum, 100% guaranteed. That’s why I can apparently play fast and loose. And for the record, it is Spain.
How does LoRa solve the problem? LoRa, like Sigfox and Weightless, operates in the 868MHz band, exhibiting even worse signal propagation characteristics.
Speaking of causing interference, LoRa is a terrible wireless technology. It is spread spectrum and causes massive congestion in ISM bands. It cannot, in the real world, manage downlink communications and it cannot mitigate uplink transmission loss during a downlink process which will continue over an extended time - all uplink Tx lost.
Absolutely agree that regulatory restrictions are in place for good reason and I don’t/won’t trample on them. The specific application is geographically isolated from any other user of the spectrum, 100% guaranteed. That’s why I can apparently play fast and loose. And for the record, it is Spain.
Then the regulations that apply in most of Europe apply to you, no exceptions for remote areas that I am aware of.
The argument that 'I am in the middle of nowhere' is often used as an argument for illegal operation, so I would conclude that the is 'middle of nowhere' place is indeed very crowded.
How does LoRa solve the problem? LoRa, like Sigfox and Weightless, operates in the 868MHz band, exhibiting even worse signal propagation characteristics.
LoRa devices can operate in the 434Mhz band also, even a brief bit of research would have shown that.
LoRa devices can cover between 10 and 30 times the distance of other devices such as HC12, meaning they can cover the same distances on 100 to 1000 times less transmitted power. It should be clear this significantly reduces interferance to other users of the spectrum.
Speaking of causing interference, LoRa is a terrible wireless technology. It is spread spectrum and causes massive congestion in ISM bands
The LoRa signal is spread over a wide bandwidth so the average interfering signal power over the typical narrow bandwidth of FSK devices (such as HC12) is very much lower.
It cannot, in the real world, manage downlink communications and it cannot mitigate uplink transmission loss during a downlink process which will continue over an extended time - all uplink Tx lost.
And neither can FSK devices, on their own.
If you want to manage transmission losses etc, then you need to apply a control protocol to the base radio technology, be it FSK (HC12) or indeed LoRa.
Crikey blimey. This is my first foray onto the friendly world of Arduino.
I am a passive chap, no aggression. But...
I have clearly stated that in this geographic location there will be zero interference. None. Nada. Zero. We can have a discussion about legality, morality, ethics. Trust me, I work in this theatre, I know about interference- see comments about LoRa. But they are irrelevant. Nobody is going to know, even less be affected by, these transmissions.
I wanted a technical response. Can we have that without the virtue signaling component? Probably not, now that I have offended you.
Your understanding of LoRaWAN is somewhat lacking. The industry joke is that the way to shut down a LoRa network is to deploy a Lora network next to it.
A LoRa network cannot manage downlink transmissions outside of the scheduled acknowledgment of a downlink transmission. This occurs only during the single, limited period immediately following the uplink transmission. LoRaWAN is not a synchronised network protocol.
LoRa does not circumvent the laws of physics. It achieves precisely zero advantage in terms of signal propagation.
So all of my questions remain, I’m looking for a way to connect my house with my gate. And there will not be any frequency police knocking on my door.
Yes, there are multiple ways - more powerful transmitter, more sensitive receiver. I would like to experiment with antennas. Both ends of the link are fixed so I can definitely deploy a directional anyanna. Yagi or Moxon? Both ends?
But I’d still like to up the Tx power. I can’t find a circuit for a 433MHz PA, or an eBay source for one. Also, I’d be happy to consider a lower frequency but again, I don’t have the experience to design my own. Legality is not relevant to this tech issue - see other exchange.
You are labouring under some fundamental misconceptions about radio. But we’ll take these one at a time...
Regulatory restrictions; I work with the people who set them in Europe; I know all about the restrictictions. I am talking about an application in a geographical area that has zero wireless conflict potential in range. You can reference regulatory legislation all you like but in the real world this use case will have no impact. The “conclusion” that you have reached that the location is “very crowded” is not only entirely wrong, wronger than a wrong thing with extra wrongness, but completely unfounded; I have no idea how you arrived at it. I wouldn’t call you an idiot if it had not been for the pretentious tone that you have chosen to adopt. You don’t even know me. You’re an idiot.
The suggestion that LoRa devices have some kind of magical ability to circumvent the laws of physics is preposterous. Do you work in the Semtech marketing department? 30X range extension? You are delusional.
100 to 1000 times less transmitted power? Are you OK? Are you really going to suggest that LoRaWAN, a massively spectrally inefficient spread spectrum protocol, somehow reduces interference with other band users? You need your head examined.
I’m going to leave this with you: there’s a reason that LoRa has a 1% duty cycle limit applied to its downlink Tx rate by ETSI in Europe. Other wireless protocols, specifically those conforming with narrowband standards, employ frequency hopping, channel nulling, listen before talk, adaptive data rate, downlink Tx power control, 100% downlink Tx scheduling. Which of those does LoRa use? Rhetorical because it is spread spectrum.
Yes, there are multiple ways - more powerful transmitter, more sensitive receiver. I would like to experiment with antennas. Both ends of the link are fixed so I can definitely deploy a directional anyanna. Yagi or Moxon? Both ends?
But I’d still like to up the Tx power. I can’t find a circuit for a 433MHz PA, or an eBay source for one. Also, I’d be happy to consider a lower frequency but again, I don’t have the experience to design my own. Legality is not relevant to this tech issue - see other exchange.
Since you are using part of the world-wide amateur radio band, look for amplifiers for 432 MHz.
Paul_KD7HB:
Since you are using part of the world-wide amateur radio band, look for amplifiers for 432 MHz.
There is a possible problem there, a lot of the 70cm PAs that you will come across require a fairly high drive power, say 1W - 5W, the output FETs are usually low gain devices (10dB or so) which is fine if your after 25W.
There is a low cost 70cm PA module out there which will work from as little as 10mW, its what I used to boost the power of the RFM22 (100mW max ISM FSK module) to allow reception at 2,200km+.
"I have a problem related solely to radio.
Do I ask the question on a specialist radio forum, or do I ask on a forum dedicated to microcontrollers?
Or, do I ask the clever folk I work with, who set the radio regulations, and presumably know a little bit about radio?"
AWOL - it’s a good point well made. I directed the post at a networking part of the forum but you’re right, we are in micro country here. To be honest this is where I’m most comfortable, RF be foreign territory and full of mumbo-jumbo.
Reality is that I don’t want to get into RF complexity. I hoped to find other digital people who had solved the same problem buying off the shelf.
Also unfortunately there are issues adding PAs to modules that appear to conflict directly with some of your requirements.
There are LoRa based modules the equivalent to the HC12, i.e. UART front ended, which would be a drop in replacement for a HC12, with some minor software changes. These modules would of course have many times the range of the HC12, as well as being legal to use. Much cheaper than the PA approach also.
I have no idea why you used the thread as an attack on LoRaWAN, I did not mention it as an option, clearly your question was about point to point comms, so using LoRaWAN would be a bit weird. Perhaps you have some vested interest in a competitor.
LoRaWAN itself is not as you assumed restricted to 868Mhz, that is the common frequency yes, but you can also use 434Mhz. Here in the UK (not sure about Spain) we have the option to also use 169Mhz. This is very useful as it has 2.5 times the range of 434Mhz and 5 times the range of 868Mhz, given the differences in free space loss. This range benefit is being used to great effect in hilly areas, where LOS is a rarity. Not sure how I know all that, given how stupid I am and my lack of understanding of LoRaWAN.
I also have no idea why you are apparently so concerned about the possible interference issues from LoRa. You are apparently operating in the middle of nowhere, and the potential interference from excess power levels on a HC12 appears to be of no concern. External PAs on FSK modules can and do produce quite large amounts of harmonic ‘interference’, requiring good additional filtering and the knowledge and equipment to measure it
mrq2u:
LoRa does not circumvent the laws of physics. It achieves precisely zero advantage in terms of signal propagation.
Indeed so, LoRa signals propogate on the same basis as wideband FSK signals such as used by RFM22, HC12 etc.
An FSK style receiver needs signals that are between 5dB and 10dB above noise level (local RF and receiver induced) in order to successfully decode them. This is easy enough to measure in practical experiments.
The LoRa receiver however, can receive signals at up to 20dB below noise level, again this is easy enough to measure in practical experiments.
Clearly operating at well below noise level, a LoRa receiver can operate with signals that are very much weaker than a typical HC12 FSK receiver can, this is where the large distance improvement comes from. Similar technology is used by GPS receivers, and the implementation of GPS in low cost devices is where concept of LoRa originated from.