Communication Range prediction for this transceiver ?

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transceiver1

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If I use this transceiver below, what kind of communication-range would I expect to get with the built-in antenna that is already inside the chip. 0.5 miles would be plenty adequate for me. I am aware that I may need to use a high-wattage "booster" at the base unit and that's fine to me. The chip will be in the mobile unit. I need to send data at 60Hz, just two floats per sample.
I need to be able to send/communicate data to the transceiver of course. But, I would also like to be able to save time-trace data from the mobile onto the base unit (ultimately its hard disk), at a rate of at least 60 data points (two floats) per second.
The chip will probably be 'protected' by about 4mm of aluminum; I don't know if that will hurt the communication range.
There will be no "mountain" or "hill" obstacles between the mobile and base.

https://rocelec.widen.net/view/pdf/v2mgfqm9mv/AMDIS006-1.pdf?t.download=true&u=5oefqw
 
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transceiver1 said:
If I use this transceiver below, what kind of communication-range would I expect to get with the built-in antenna that is already inside the chip. 0.5 miles would be plenty adequate for me. I am aware that I may need to use a high-wattage "booster" at the base unit and that's fine to me. The chip will be in the mobile unit. I need to send data at 60Hz, just two floats per sample.
I need to be able to send/communicate data to the transceiver of course. But, I would also like to be able to save time-trace data from the mobile onto the base unit (ultimately its hard disk), at a rate of at least 60 data points (two floats) per second.
The chip will probably be 'protected' by about 4mm of aluminum; I don't know if that will hurt the communication range.
There will be no "mountain" or "hill" obstacles between the mobile and base.

https://rocelec.widen.net/view/pdf/v2mgfqm9mv/AMDIS006-1.pdf?t.download=true&u=5oefqw
Click to expand...

That chip is not an RF Device. It’s designed to interface to a wired data bus.
 
cls said:
Use something like this

https://www.adafruit.com/product/5693

Be sure to fit good antennas at both ends.
Click to expand...
Assuming the RFM69HCW is 8mm or less in width, how large will the mobile antenna have to be. We can assume the base antenna to have unlimited dimensions and unlimited wattage.
edit: from page 78 of the datasheet below, it looks like the RFM69HCW is 16mm, too big for me.
https://cdn.sparkfun.com/datasheets/Wireless/General/RFM69HCW-V1.1.pdfedit2: maybe this "transceiver radio", 7mmx5mm:
https://mm.digikey.com/Volume0/opasdata/d220001/medias/docus/560/Si1000-5.pdfedit3: still need the mobile antenna part, to my understanding.
 
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No comment on the RF hardware.

However, looking at the Data Rate:
Float = 32 bits, Double = 64 bits. With Start & Stop bits there are 40 or 80 bits to send for each Floating point number
At 60Hz the rate is 4800 bits/second which is easy for nearly any RF transmission.
At 4800Baud, the data stream is constantly full so better to up the transmission data rate to 9600Baud.
 
Art Upton said:
The antenna wire should be 1/4 of the wavelength of the frequency used for the RF transmitter; about 6.7 inches for 433mhz
Click to expand...
I will only have room for something on the order of 1 inch, so I guess I need to run about 3000Mhz.
433/3000 ~ 1/6.7
I read somewhere that aluminum is "RF transparent" (if that's true?). So, I could have my 'wire' antenna inside of an Aluminum tube if I need to? I just assume the aluminum and 'copper wire antenna' will have to be separated by epoxy or plastic, e.g.
 
transceiver1 said:
I will only have room for something on the order of 1 inch, so I guess I need to run about 3000Mhz.
433/3000 ~ 1/6.7
I read somewhere that aluminum is "RF transparent" (if that's true?). So, I could have my 'wire' antenna inside of an Aluminum tube if I need to? I just assume the aluminum and 'copper wire antenna' will have to be separated by epoxy or plastic, e.g.
Click to expand...
If you work it right you could make that aluminum tube into your antenna.

But really, tell us more about what you’re doing. Is that tube your rocket body? What are you using for a motor? Is this a school project? What regulatory issues have you considered?
 
transceiver1 said:
I will only have room for something on the order of 1 inch, so I guess I need to run about 3000Mhz.
433/3000 ~ 1/6.7
I read somewhere that aluminum is "RF transparent" (if that's true?). So, I could have my 'wire' antenna inside of an Aluminum tube if I need to? I just assume the aluminum and 'copper wire antenna' will have to be separated by epoxy or plastic, e.g.
Click to expand...
You really need to study RF theory. Take the advice offered above, and get your ham license at the same time.
 
Steve Shannon said:
If you work it right you could make that aluminum tube into your antenna.

But really, tell us more about what you’re doing. Is that tube your rocket body? What are you using for a motor? Is this a school project? What regulatory issues have you considered?
Click to expand...
..and...why not buy something off the shelf? Maybe you want to make your own,? Have you searched this entire forum looking for what you want to make/build/buy?
Research (Googling) is an easy and fast way to dial in on what or who you're looking for ...to help answer your questions.

Tony
 
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Steve Shannon said:
If you work it right you could make that aluminum tube into your antenna.
Click to expand...
That is what I was thinking last night when I was supposed to be sleeping. Why not let the mobile, or part of it rather, BE the antenna. I assume I would just solder the associated pin of the transceiver radio chip directly to the chassis. Is there any reason an antenna has to have a super-large aspect ratio (length over width) or is 20 or 10, e.g., big enough ?
Ok, I think I will go work on my truck in the garage, as parts finally arrived, and as I wait for the "invisible-messages" stuff to go away, i.e., "This message is awaiting moderator approval, and is invisible to normal visitors"
 
transceiver1 said:
I will only have room for something on the order of 1 inch, so I guess I need to run about 3000Mhz.
433/3000 ~ 1/6.7
I read somewhere that aluminum is "RF transparent" (if that's true?). So, I could have my 'wire' antenna inside of an Aluminum tube if I need to? I just assume the aluminum and 'copper wire antenna' will have to be separated by epoxy or plastic, e.g.
Click to expand...
The RFM69HCW uses LoRa which has a very large link budget (I've seen numbers as large as 160dB). LoRa can work with a signal as low as -149dBm. That means in order for the reciever to decode the signal, the power of the signal it recieves must be at least around 10^-15 watts, which is MUCH smaller than the typical 17dBm (50 milliwatt) transmitter power. The most efficent antenna you could probably use is a 70cm Yagi, which has a max gain of around 28dBi. This means it is only 28 dB more efficient than the least efficent antenna (an isotropic antenna). In other words, a very efficent antenna results in only a 28dB increase in the effective transmitted power, and LoRa can work when the recieved signal is 160dB weaker than the transmitted signal, i.e., the efficiency of the antenna hardly matters. Indeed, you will see in long range LoRa gateways the antenna is a only a short stub a few inches long, and will still send packets 100km+ away.

If you need a antenna shorter than an inch, I would look into a "short dipole".
https://www.hamradiosecrets.com/short-ham-antennas.html

Essentially, once you are under 1/10 wavelength (2.7 inches for 433 MHz), the exact ratio of the antenna does not matter. It will be inefficent, but as demonstrated the effciency hardly matters. In fact I would not even bother using loading coils (as explained on the linked website), I would just use a simple wire dipole (two equal lengths of wire 0.5 inches each) and experiment with that. There are cheap Lora modules on the Adafruit website that use 900 MHz, so you may be able to achieve 1/10 wavelength with 1 inch. I would still reccomend a Yagi antenna for the base station, as they are incredibly cheap to make and cut down on the noise.

However, I will note that 1 inch is an incredibly strange design constraint for an electronics bay. Even on a tiny 24mm rocket, the ebay would be a few inches long. What specifically is limiting you to 1 inch?
 
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My thoughts about some of the comments above...
For space communications a range of 150km is possible but for average conditions it is not likely.
From the LoRa web page...

Table 1: LoRa Spreading Factors

Spreading_Factors.png
https://lora-developers.semtech.com/documentation/tech-papers-and-guides/lora-and-lorawan

A 28 dBi yagi is not a small antenna. My 432 MHz EME antenna that I used for moonbounce consisited of 4 yagi antennas, each with a boom length of 33 feet. The yagis were spaced out both horizontally and vertically about 7 feet. It had a measured gain on 26 dBi. A small handheld yagi antenna suitable for tracking a rocket would have a gain of about 6 to 8 dBi.

An amateur radio license is required in the US to use 433 MHz.

Aluminum is not transparent at RF frequencies.

An isotropic antenna is not the "least efficient" antenna possible. An isotropic antenna is a theoretical antenna that radiates equally in all directions. As an example the common so called rubber duck antenna found on most hand held radios is a poorer radiator than the isotropic antenna.

If the original poster were to buy some LoRa modules he will need to provide the firmware to make it work.

Are there any GPS patch antenna/receivers small enough to fit in the space that is available?

This is not to say that LoRa couldn't be used for a tracking system but let's be realistic what it can do.
 
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OP posted he wants 60Hz updates, not sure how many bits per update. LoRa isn't built for that.
 
RocketDestroyer said:
My thoughts about some of the comments above...
For space communications a range of 150km is possible but for average conditions it is not likely.
From the LoRa web page...

Table 1: LoRa Spreading Factors

Spreading_Factors.png
https://lora-developers.semtech.com/documentation/tech-papers-and-guides/lora-and-lorawan

A 28 dBi yagi is not a small antenna. My 432 MHz EME antenna that I used for moonbounce consisited of 4 yagi antennas, each with a boom length of 33 feet. The yagis were spaced out both horizontally and vertically about 7 feet. It had a measured gain on 26 dBi. A small handheld yagi antenna suitable for tracking a rocket would have a gain of about 6 to 8 dBi.

An amateur radio license is required in the US to use 433 MHz.

Aluminum is not transparent at RF frequencies.

An isotropic antenna is not the "least efficient" antenna possible. An isotropic antenna is a theoretical antenna that radiates equally in all directions. As an example the common so called rubber duck antenna found on most hand held radios is a poorer radiator than the isotropic antenna.

If the original poster were to buy some LoRa modules he will need to provide the firmware to make it work.

Are there any GPS patch antenna/receivers small enough to fit in the space that is available?

This is not to say that LoRa couldn't be used for a tracking system but let's be realistic what it can do.
Click to expand...

I agree with your comment about the range, with trees and other terrain the range is usually limited to a few km (although still definitely capable of the 0.5 miles OP asked for). With direct LOS, it can be much higher than that especially with directional antennas. Adafruit makes 900MHz (no license required) versions of their LoRa boards, and their 900 MHz RFM95 LoRa board claims a max range of 20km.

A 28 dBi yagi would definitely be too large for this application, I was just trying to illustrate the point that even a very high gain antenna vs a very low gain one does not make much of a difference with LoRa.

I guess I was being imprecise when I used the word "efficient". I meant that due to the high directivity of a Yagi, the RF power transmitted would be concentrated in the direction of the receiver, rather than uniformly in all directions. Therefore it is more "efficient" in the sense that for the same amount of RF power, the Yagi transmits more of that power to the reciever. You're correct that there are antennas that are much more inefficient in the typical sense, like rubber duck antennas, in that they are bad at converting electrical power to RF power.

As for the firmware, Adafruit has very good documentation, tutorials, and software examples for their products. I'm not sure what kind of chip OP is using, but sending two floats over I2C or SPI should be relatively simple with the code they provide.
 
cls said:
OP posted he wants 60Hz updates, not sure how many bits per update. LoRa isn't built for that.
Click to expand...
You are likely right but I think I'm missing something. OP asked for two floats of data at 60hz. Two floats is 64 bits. At 60 Hz that is 3.84 kbps. That seems to be well within the capabilities of LoRa.
 
60 Hz and "two floats per sample" would be about 960 bytes (8 bytes per float), so that's a minimum of 9600 baud continuously. Eggfinder transmitters send at 9600 baud, albeit at about a 10%-20% duty cycle, and we manage to get several miles of range out of 100 mW due to the very good link budget of the transceivers that we use.

transceiver1, you REALLY need to do some studying on how RF works before you try to design something from scratch, there are plenty of pre-made solutions at the module level that will easily fulfill your 1/2 mile range requirement. Try Googling "drone telemetry", you'll find plenty of them.
 
Art Upton said:
The antenna wire should be 1/4 of the wavelength of the frequency used for the RF transmitter; about 6.7 inches for 433mhz
Click to expand...
If my antenna were 11.1inches long (and say 0.63inches diameter), will that have any chance of working at 433Mhz? That would be a 0.407*lambda antenna length, where lambda is the RF wavelength.
Same question for 2400Mhz. Would the above 11.1inch antenna have any chance of working. That would be a 2.26*lambda antenna length.
 
transceiver1 said:
If my antenna were 11.1inches long (and say 0.63inches diameter), will that have any chance of working at 433Mhz? That would be a 0.407*lambda antenna length, where lambda is the RF wavelength.
Same question for 2400Mhz. Would the above 11.1inch antenna have any chance of working. That would be a 2.26*lambda antenna length.
Click to expand...
Not trying to be a noodge, but you REALLY need to read up on RF theory instead of constantly asking the Forum to give you your answers. You already have been told that the antenna should be about 1/4 the wavelength of your signal... you should be able to easily figure that out.
 
cerving said:
Not trying to be a noodge, but you REALLY need to read up on RF theory instead of constantly asking the Forum to give you your answers. You already have been told that the antenna should be about 1/4 the wavelength of your signal... you should be able to easily figure that out.
Click to expand...
Yes, but some information online states that the antenna length over wavelength is only allowed to be one of the below values:
1/4, 1/2, 1, 2, 4, 8, 16, 32, 64, etc.
Other information online states the antenna length over wavelength simply needs to be AT LEAST 1/4 of the wavelength, meaning any value greater or equal to 0.25 is fine.

THERE IS A MASSIVE DIFFERENCE BETWEEN THOSE TWO PIECES OF INFORMATION.
AND, I NEED TO KNOW WHICH IS WHICH AND WHAT IS WHAT.
 
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In my application, my rod-length ("wire length") is fixed. It cannot be changed. The only things I can fiddle with are: transmission frequency, and the LOCATION on my 11.1inch-rod at which I attach the receiver pin.
I guess I can just proceed to try twiddling the attachment point and see if it works or not.....
 
transceiver1 said:
If my antenna were 11.1inches long (and say 0.63inches diameter), will that have any chance of working at 433Mhz?
Click to expand...
If you have a relatively thick antenna, as you do in this case, it will actually make the length electrically shorter than it would be for a thin wire. To scale antenna designs you need to scale both lengths and diameters of the elements to keep the frequency right.
 
There's also the velocity factor of your antenna material to consider, plus whatever impedence matching network you might need. Ham radio operators spend a lot of time (and money on equipment) to optimize their antennas. If you want to study how to do that, Google "antenna matching". There are relatively inexpensive pieces of equipment on the market now (such as vector network analyzers) that will help you with this. That being said, you're trying to start at the end... you need to start at the beginning. Since you seem to be an Arduino person, Google "Arduino RF69" and you can read all about how to create a data link with two Arduinos and two RF69 breakout boards. Don't get hung up about the antenna... you're a long ways away from the point at which it matters much.
 

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