Most reliable "best" radio
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Regarding the antenna extensions, you raise some good points. The people who posted them seem like they thought it genuinely helped, but maybe I was gullible and was wrong to post the links. If so, I'm sorry. On the other hand, it might take only 5 minutes to try them out and see whether or not they work. A simple trial experiment would maybe settle it one way or the other pretty quickly.
@skywatch said in Most reliable "best" radio:
Here is the link to the E32 arduino library..... https://www.arduino.cc/reference/en/libraries/ebyte-lora-e32-library/
Thanks. What was it you were wanting me to notice about the e32 library? If it was about the FHSS, that was an e34 module in the youtube video.
@NeverDie said in Most reliable "best" radio:
Regarding the antenna extensions, you raise some good points. The people who posted them seem like they thought it genuinely helped, but maybe I was gullible and was wrong to post the links. If so, I'm sorry.
We are all here to share and learn and help each other out - I was only adding my thoughts on the matter for all to consider.
On the other hand, it might take only 5 minutes to try them out and see whether or not they work. A simple trial experiment would maybe settle it one way or the other pretty quickly.
Yes it would, but positioning needs to be carefully maintained to avoid false results.
@skywatch said in Most reliable "best" radio:
Thanks. What was it you were wanting me to notice about the e32 library? If it was about the FHSS, that was an e34 module in the youtube video.Oh darn it! - I got it mixed up - I am sorry for posting the wrong lib!
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@NeverDie said in Most reliable "best" radio:
Regarding the antenna extensions, you raise some good points. The people who posted them seem like they thought it genuinely helped, but maybe I was gullible and was wrong to post the links. If so, I'm sorry.
We are all here to share and learn and help each other out - I was only adding my thoughts on the matter for all to consider.
On the other hand, it might take only 5 minutes to try them out and see whether or not they work. A simple trial experiment would maybe settle it one way or the other pretty quickly.
Yes it would, but positioning needs to be carefully maintained to avoid false results.
@skywatch said in Most reliable "best" radio:
Thanks. What was it you were wanting me to notice about the e32 library? If it was about the FHSS, that was an e34 module in the youtube video.Oh darn it! - I got it mixed up - I am sorry for posting the wrong lib!
@skywatch said in Most reliable "best" radio:
Yes it would, but positioning needs to be carefully maintained to avoid false results.
I think for a gateway it could make sense to use two nRF24L01 modules spaced a half wavelength apart. Then for reception you'd get all the benefits of antenna diversity, and for transmission to a particular node you could simply pick the module that receives the most packets out of the two from that node, which should give the better signal path. That could cut down on the sensitivity to positioning by better avoiding null zones.
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@NeverDie That 'antenna modification' just looks crazy to me, but I have not tried it. However the designers will have spent some time on getting the pcb stripline antenna to be matched to the transmitters impedance. Adding a random bit of wire on the end will screw this up royally.. You never see this on TV antennas or anywhere else for that matter (maybe some nutter with a car aerial made from a coat hanger).
Also I would expect that the design is to be as wide band as possible but centered on the mid frequency in the range available. So the further you move away from 'centre' frequency (Ch63) then the worse the antenna is likely to perform. But at the power levels used here the effects might be marginal. I have always found moving the RF board a cm or two can make a big difference in link quality.
Here is the link to the E32 arduino library..... https://www.arduino.cc/reference/en/libraries/ebyte-lora-e32-library/
@skywatch said in Most reliable "best" radio:
That 'antenna modification' just looks crazy to me,
And that is why it will be fun to test. I corrected my post above and made comments on testing.
[Edit: It was my bad for drawing people down this dark alley of antenna modifications. I’ve learned much from dark allies and only been beaten-up a few times. Yet, I still go there… to learn. Therefore, I will test it and reply.]
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I just now did a current measurement, and, unfortunately, the allegedly smd NRF24L01's on amazon do not appear to be either nRF24L01's nor si24R1's, because the max Tx current is not a match for either:
The Tx current is too high to be an nRF24L01, and it's too low to be an si24R1. I'll have to look at some of the alternative datasheets to determine just what it is. -
@skywatch said in Most reliable "best" radio:
Yes it would, but positioning needs to be carefully maintained to avoid false results.
I think for a gateway it could make sense to use two nRF24L01 modules spaced a half wavelength apart. Then for reception you'd get all the benefits of antenna diversity, and for transmission to a particular node you could simply pick the module that receives the most packets out of the two from that node, which should give the better signal path. That could cut down on the sensitivity to positioning by better avoiding null zones.
@NeverDie I've been playing with KiCAD and working with your BareBones_2AA_Arduino. Given the disucssion on the "Anyone using..." thread about ground planes it jumped out at me that your design uses no ground plane. Of course there isn't any room left either. Does that matter? I see that your radio boards, like the RFM69_900 have solid ground planes.
To look at further, I looked at the ProMini design by Sparkfun. Pictures are attached of the grounded fills they used. These pictures are of only the top and bottom copper for illustration. I'm thinking this would bother Eric Bogatin and he would say to throw in another layer dedicated to ground signal. Again, do you think it matters?
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@NeverDie I've been playing with KiCAD and working with your BareBones_2AA_Arduino. Given the disucssion on the "Anyone using..." thread about ground planes it jumped out at me that your design uses no ground plane. Of course there isn't any room left either. Does that matter? I see that your radio boards, like the RFM69_900 have solid ground planes.
To look at further, I looked at the ProMini design by Sparkfun. Pictures are attached of the grounded fills they used. These pictures are of only the top and bottom copper for illustration. I'm thinking this would bother Eric Bogatin and he would say to throw in another layer dedicated to ground signal. Again, do you think it matters?
@Larson I think it probably does matter, but that a dipole antenna may be a good workaround to not having an optimal ground plane. I say that because a number of years ago a group of us on the lowpowerlab forum found that adding a dipole antenna to the rfm69 module resulted in a significant range improvement.
Part of the problem is that an optimally sized ground plane is actually quite large relative to an otherwise small mote, especially at sub-gigahertz frequencies. So, if you were to build an optimally sized ground plane into your PCB, your mote wouldn't be small anymore. Even a dipole antenna can be so large as to be cumbersome. This antenna: https://lowpowerlab.com/shop/product/193?search=dipole
was an outgrowth of the discussion and work that the group did, and, as you can see, it's not tiny. However, it might be feasible on a gateway, where size may not matter as much.So, short of that, should I try to add more ground plane? I really don't know. More is probably better, but I'm not smart enough to tell you how much difference a marginal increase would make. Adding a dipole antenna very definitely did make a noticeable difference though.
Maybe somebody reading this who knows more than me can comment.
Also, part of the reason I didn't add more groundplane was that it would negatively affect the current layout for the two 2.4Ghz horizontal trace antenna readios, which aren't supposed to be mounted over a ground plane. That could be rectified by moving the antenna module to the end of the board, where the trace antenna could hang off the end in empty space, but that's a version 2.0 design. Version 1.0 was just trying to get something ordered from a fab as quickly as possible, and the adapter board placement is something I would change for a v2.0. With that change, there'd be no reason not to do a copper pour and have a nice ground plane--well, within the mote's size constraints.
There's also more to it than just ground plane. There's the whole matter of impedance, which is hugely important. Smith charts, etc. I don't have more than a superficial grasp on how antennas are supposed to be designed, so I'm really the wrong person to ask about everything that's involved. From what I've read, even the particular dielectric that's used in your PCB can make a meaningful difference. Andreas Speiss did do an episode on how you can use a VNA to tune your antenna better. It might be worth a look. To me it looks like a very deep rabbit hole, and a very steep and very challenging learning curve, so it just depends how far down the rabbit hole you're willing to go. The way I see it, and maybe this is just me, I would hit diminishing returns almost immediately for the amount of effort that's required. That isn't to say that you shouldn't do it though. ;-)
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@Larson Here's the list of nRF24L01 clones and variants: https://sigrok.org/wiki/Protocol_decoder:Nrf24l01
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@Larson I think it probably does matter, but that a dipole antenna may be a good workaround to not having an optimal ground plane. I say that because a number of years ago a group of us on the lowpowerlab forum found that adding a dipole antenna to the rfm69 module resulted in a significant range improvement.
Part of the problem is that an optimally sized ground plane is actually quite large relative to an otherwise small mote, especially at sub-gigahertz frequencies. So, if you were to build an optimally sized ground plane into your PCB, your mote wouldn't be small anymore. Even a dipole antenna can be so large as to be cumbersome. This antenna: https://lowpowerlab.com/shop/product/193?search=dipole
was an outgrowth of the discussion and work that the group did, and, as you can see, it's not tiny. However, it might be feasible on a gateway, where size may not matter as much.So, short of that, should I try to add more ground plane? I really don't know. More is probably better, but I'm not smart enough to tell you how much difference a marginal increase would make. Adding a dipole antenna very definitely did make a noticeable difference though.
Maybe somebody reading this who knows more than me can comment.
Also, part of the reason I didn't add more groundplane was that it would negatively affect the current layout for the two 2.4Ghz horizontal trace antenna readios, which aren't supposed to be mounted over a ground plane. That could be rectified by moving the antenna module to the end of the board, where the trace antenna could hang off the end in empty space, but that's a version 2.0 design. Version 1.0 was just trying to get something ordered from a fab as quickly as possible, and the adapter board placement is something I would change for a v2.0. With that change, there'd be no reason not to do a copper pour and have a nice ground plane--well, within the mote's size constraints.
There's also more to it than just ground plane. There's the whole matter of impedance, which is hugely important. Smith charts, etc. I don't have more than a superficial grasp on how antennas are supposed to be designed, so I'm really the wrong person to ask about everything that's involved. From what I've read, even the particular dielectric that's used in your PCB can make a meaningful difference. Andreas Speiss did do an episode on how you can use a VNA to tune your antenna better. It might be worth a look. To me it looks like a very deep rabbit hole, and a very steep and very challenging learning curve, so it just depends how far down the rabbit hole you're willing to go. The way I see it, and maybe this is just me, I would hit diminishing returns almost immediately for the amount of effort that's required. That isn't to say that you shouldn't do it though. ;-)
@NeverDie said in Most reliable "best" radio:
so it just depends how far down the rabbit hole you're willing to go.
I'm deep in the rabbit hole already and its getting colder and darker. Thank you for your detailed discussion - especially the diminishing-return comment. Yea, I should focus on doing and reporting back - something to show for all I have learned. I remember the 6" dia ground plane idea. Yes, that is a deal-killer. I'd opt for sheet metal befoe building a PCB that big.
Again, Thank You!
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Not completely sure yet, but going down the list of clones/variants datasheets, but it looks as though the amazon smd "nRF24L01" modules may be using the XN297 chip:
I suppose additional measurements, like sleep current and standby current, may either confirm it or not. Also, if it can't support 250kbps, that might also give it away.
According to the datasheet, it may go as high as 8dBm on Tx, so at least that would be consistent with the "enhanced power mode" advertising in the amazon.com listing. -
Well, I checked, and the mystery modules can do 250kbps, so evidently it is not the XN297. That was my best guess, and now I have no idea what it is. The sigrok list of clones and variants hasn't been updated in many years.
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Well, I checked, and the mystery modules can do 250kbps, so evidently it is not the XN297. That was my best guess, and now I have no idea what it is. The sigrok list of clones and variants hasn't been updated in many years.
@NeverDie said in Most reliable "best" radio:
The sigrok list of clones and variants hasn't been updated in many years.
Yes, I saw the list of 2 originals and I counted 12 clone/variants. And that list was from 2015 and it is still instructive. If the chips are compatible and deliver value, then it is sufficent for those on the learning curve, like me. Probably not sufficient for market tested commercial products.
Fun to see the Nordic employee comment about a datasheet error that ended up in a clone. I remember that paper roadmap makers from 50-years ago, like Rand, used to deliberately make mapping errors to catch clones. Times have changed and methods haven't. The die comparisons referenced in links to your link are, again, mind blowing.
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@NeverDie said in Most reliable "best" radio:
The sigrok list of clones and variants hasn't been updated in many years.
Yes, I saw the list of 2 originals and I counted 12 clone/variants. And that list was from 2015 and it is still instructive. If the chips are compatible and deliver value, then it is sufficent for those on the learning curve, like me. Probably not sufficient for market tested commercial products.
Fun to see the Nordic employee comment about a datasheet error that ended up in a clone. I remember that paper roadmap makers from 50-years ago, like Rand, used to deliberately make mapping errors to catch clones. Times have changed and methods haven't. The die comparisons referenced in links to your link are, again, mind blowing.
@Larson said in Most reliable "best" radio:
If the chips are compatible and deliver value, then it is sufficent for those on the learning curve, like me
I think that's the right attitude. The main difference, aside from differences in how they handle ACK (which most software now accommodates for) is that most clones/variants are not as energy efficient as the original. For instance, this particular clone, whatever it is, has a sleep current of something like 1.5ua-1.8ua, as opposed to Nordic's 0.7ua. So, that's worse, but it may not be a deal breaker.
The newer Nordic nRF5x series chips are definitely a lot more efficient at listening, with receive currents down in the 2.6ma-~5ma range when DCDC conversion is turned on. That compares very favorably to the 15ma and up of the nRF24L01/clones. Of course, a tradeoff is cost and, these days, availability. nRF52805 is "cheap" at around $4, and it's available, so at 4.6ma in RX, it's maybe not a bad choice, considering it includes an RTC and MCU. Its sleep current with RAM retention and RTC is an improvement over the prior nRF52840 flagship. The nRF52805's native Tx power is weak, but for listening it might be adequate. I think I'll order some to try.
The current flagship is the nRF5340, which is the one that has the 2.6ma Rx current. Presently it is the only one in the nRF53x series.
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@skywatch said in Most reliable "best" radio:
That 'antenna modification' just looks crazy to me,
And that is why it will be fun to test. I corrected my post above and made comments on testing.
[Edit: It was my bad for drawing people down this dark alley of antenna modifications. I’ve learned much from dark allies and only been beaten-up a few times. Yet, I still go there… to learn. Therefore, I will test it and reply.]
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@skywatch said in Most reliable "best" radio:
Yes it would, but positioning needs to be carefully maintained to avoid false results.
I think for a gateway it could make sense to use two nRF24L01 modules spaced a half wavelength apart. Then for reception you'd get all the benefits of antenna diversity, and for transmission to a particular node you could simply pick the module that receives the most packets out of the two from that node, which should give the better signal path. That could cut down on the sensitivity to positioning by better avoiding null zones.
@NeverDie I know what you mean, but "half a wavelength apart would have them in very close proximity with risk of interference. Better if the were 300mm+half a wavelenght apart. But can mysensors cope with 2 gateways on the same frequency? I didn't think that would be possible... Or were you thinking one gateway node with 2x RF modules? Now that would be interesting!
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@NeverDie I know what you mean, but "half a wavelength apart would have them in very close proximity with risk of interference. Better if the were 300mm+half a wavelenght apart. But can mysensors cope with 2 gateways on the same frequency? I didn't think that would be possible... Or were you thinking one gateway node with 2x RF modules? Now that would be interesting!
@skywatch said in Most reliable "best" radio:
@NeverDie I know what you mean, but "half a wavelength apart would have them in very close proximity with risk of interference. Better if the were 300mm+half a wavelenght apart. But can mysensors cope with 2 gateways on the same frequency? I didn't think that would be possible... Or were you thinking one gateway node with 2x RF modules? Now that would be interesting!
Either way, I suppose.
Anyway, I ordered the last 10 of the nRF52805's modules from a supplier at just $2.50 each. At that price I would have bought more, but that's all they had. I think that for that price it's a very convenient integrated MCU + radio package for Rx listening and very short-range communication. I look forward to seeing whether the arduino software for the nRF52x arduino library support has noticeably improved since the last time I tried the nRF52x series. I have fond memories of programming it then, and it can only have gotten better since then. Yes? Hopefully? Funny enough a $1 si24R1 will beat it on transmission oomph, but, meh, the nRF52805 wins with 1/3 the Rx current and decently low sleep current, even with built in RTC turned on and full RAM retention.
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@skywatch Will be interested in your results!
Here is my proposal for a test of antenna modifications that I will attempt:
- Keep it fun, light and fast.
- Use ESP8266's (ESP01's or ESP12's) because I've got some to burn.
- Antenna modifications only on either receive or transmit (recommendations?)
- Based on ESP-NOW protocol - my comfort zone.
- Report on RSSI and SNR.
- Pick one fixed range so I can keep this close to home and limited in scope.
- Most importantly, follow the hack of Pete B. and record
A. base case original
B. the 1.0, 0.75, 0.5, 0.25 wave length options
C. finally test the base case again.
Any suggestions on other points? I really don't want to burden/distract NeverDie's fine thread here, though I fear I have already. I've never hosted a thread and really don't want to. Perhaps I can post a spreadsheet somewhere.
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@skywatch Will be interested in your results!
Here is my proposal for a test of antenna modifications that I will attempt:
- Keep it fun, light and fast.
- Use ESP8266's (ESP01's or ESP12's) because I've got some to burn.
- Antenna modifications only on either receive or transmit (recommendations?)
- Based on ESP-NOW protocol - my comfort zone.
- Report on RSSI and SNR.
- Pick one fixed range so I can keep this close to home and limited in scope.
- Most importantly, follow the hack of Pete B. and record
A. base case original
B. the 1.0, 0.75, 0.5, 0.25 wave length options
C. finally test the base case again.
Any suggestions on other points? I really don't want to burden/distract NeverDie's fine thread here, though I fear I have already. I've never hosted a thread and really don't want to. Perhaps I can post a spreadsheet somewhere.
@Larson said in Most reliable "best" radio:
I really don't want to burden/distract NeverDie's fine thread here, though I fear I have already.
No worries. I welcome it. Literally, any content is good content as far as I'm concerned.
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@Larson said in Most reliable "best" radio:
I really don't want to burden/distract NeverDie's fine thread here, though I fear I have already.
No worries. I welcome it. Literally, any content is good content as far as I'm concerned.
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@NeverDie said in Most reliable "best" radio:
No worries. I welcome it. Literally, any content is good content as far as I'm concerned.
You remind me of my favorite teachers/professors. I was lucky to have many.
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@Larson This is kinda bluesky, but I was thinking it would be nice to have not just different radio modules to be pluggable into a test platform, but maybe even different MCU's to be similarly pluggable That way when moving from one version of the test platform to the next, you wouldn't necessarily have to desolder mcu's and other parts. I guess what I'm saying is that maybe the test platform could be either mainly or entirely a backplane that things get plugged into. Especially these days, when finding available MCU's is kinda hit or miss, and you might have to switch to a different MCU because of either price or availability. Anyhow, just putting the idea out there. I'm not at all sure what the best form of such a thing would be, but something that revolves around 2xAA batteries as the form factor makes sense to me.
