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- čas přidán 2. 02. 2018
- LoRa and ESP32 are everybody’s darlings, and when a combination in the form of these small boards appeared on our platforms, it seemed they are a perfect combination. Is this true? Let’s test them.
- A 433 MHz Heltec
- An 868-915MHz Heltec
- An 868-915 TTGO
- And as a reference the Hope RFM95 868 MHz
These boards can be used as LoRa nodes and as TTN gateways.
In this video we have a closer look at these features:
- The ESP32
- The LoRa transceiver
- The antennas
- And the power management part
Links:
TTN Forum: bit.ly/2GFo0TN
ESP32 LorRa Boards: s.click.aliexpr...
LoRa32u4: s.click.aliexpr...
Whisper Node Lora: bit.ly/2GCB0td
dB vs VSWR: ww2.minicircui...
Antennas: s.click.aliexpr...
Supporting Material and Blog Page: www.sensorsiot.org
Github: www.github.com...
My Patreon Page: / andreasspiess
If you want to support the channel, please use the links below to start your shopping. No additional charges for you, but I get a commission (of your purchases the next 24 hours) to buy new stuff for the channel
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I do have to thank Andreas for this one; ain't many of us hobbyists that have the kind of hardware to test antennas like this properly, so it's very nice that he does it for us.
Nita Vesa agreed, I would have never realized this until I either test myself or see this video. Unfortunately I do not have anything exotic instrument nor detailed knowhow of RF field.
Thanks!
Who needs a lab or an external analysis company when you have Andreas as a friend ??!! Always torough, accurate and rigorous ! Danke !
You are welcome!
Perfect and in details analysis. Congratulations Mr. Spiess!
Thank you!
This channel has some of the best videos on CZcams!!!
Thanks!
As a Patreon supporter it sure is nice getting the videos early! More of your subscribers should take advantage of the opportunity. The new boards have a very attractive of combinations of features. I reviewed them last week and came to the same conclusion that you did - not quite ready for prime time. Hopefully their shortcomings will be addressed in V2 hardware
Thank you for your support! The V2 is already on order. We will see...
Excellent analysis! You truly live up to what we expect from engineers in the DACH region.
I’m so glad I saw this before purchasing a set of modules.
Glad I am able to help prevent bad purchases!
Sr.. im been looking your channel since 2 years ago. I really appreciate your efforts to present everything in your videos as crystal they looks and so simple in a matter that probably looks complex to many..... It is a shame that you have only 200K+ subscribers but would like to tell you in, a way to tank you, that all my customers are received better solutions thanks to you.
Thank you for your nice words. I am glad my work helps you!
Good Morning Andreas
Another well done and very informative vid. Very germain at the moment for me as I've just completed a Project Spec/Definition on a multi end-point surveillance system for my equipment trailer and SUV.
The SUV will act as a relay station for the trailer module which is positioned 200-300 feet away and the control end-point is at my side or in my pocket.
I plan on using an ESP32 based module for all points in the network and a second relay module so that all midules will be line-of-sight in a three hop system.
Your work on ESP8266/32, LAN/WAN/LoRa has transformed from being interesting to invaluable for me.
I always watch your vids with keen interest and intend to watch your entire series of comm-ctrlr vids.
I am also very appreciative of no music, no fluff, moocho info and a professional presentation.
You simply do awfully good work.
Regards/73
Russ in NH/KA1RUW
Thank you for your precise feedback. You have a very interesting project!
This was extremely useful, Andreas! You saved me a lot of time. Again!
For those who need but can't afford a spectrum analyzer, it is possible to do inaccurate (but practical) testing of RF transmitters using $20 software-defined radios (SDRs) and Open Source software e.g., SDRsharp.
Thanks for your tip!
An SDR will, as part of its normal operation, display several useful characteristics of a given transmitted signal: signal strength, frequency, bandwidth, adjacent or overlapping signals that might squirrel up the S/N ratio of the receiver, etc. In fact, the only function of a spectrum analyzer that can't be directly reproduced with an SDR is precise quantification and measurement of the signal of interest. That functionality is seldom useful in experimentation, but it can be added to an SDR via external filters, amplifiers, and/or attenuators to allow very precise measurement of whatever you need measured. A spectrum analyzer just combines the SDR functionalities, the filters, amps, and attenuators in one box with an interface usable even by people who don't understand RF, but can follow a step-by-step recipe.
PS: SDRsharp is a software solution. It allows you to add plugin decoders, demultiplexers, transcoders, or any other instrumentation you can conceive. And, there are a lot of decoders already written. So, if you want to see the RF aspects of a signal AND the content of that signal, all you need do is pull up vim (the only editor worth its storage footprint) and start typing. :o)
I don't know of anyone else specifically using an SDR as a spectrum analyzer. It's kind of odd, as that was the whole reason I bought an SDR: to see the spectrum around a specific frequency of interest. They're used for all kinds of oddball things. I think the first one was sold as a TV receiver dongle, and someone else wrote different software for it, and thus the SDR fad was born. The desire for step-by-step procedures is a good indicator that you want to get a real spectrum analyzer. eBay, ham conventions, etc are your friend.
For things like casual LORA evaluation, an SDR is more than adequate. NOOELEC's dongle just works with Windows 10, Ubuntu/LinuxMint, and MacOS (I've used one on all four OSes). SDR gear, overall, is not a mainstream solution, and everyone involved in that sub-sub-hobby assumes that SDR users have a lot of radio electronics and software skills. If you're hitting brick walls hooking up a USB stick and running Windows software, then you probably don't want to waste your time in that hardware/software rabbit hole - you just want results. So, get a dedicated spectrum analyzer, get the analysis you wanted, make something insanely cool.
Loved the Maradona joke. Thanks so much Andreas for the technical analysis and for your Swiss sense of humour !
Thank you. Glad you liked the content!
Thanks Andreas for your videos. You also have "la mano de Dios" like Maradona on MCUs and sensors
Again an overwhelming video with deep technical backround. And I'm a little bit envious on your pool of measuring instruments.
This is the result of my age ;-)
Antenna measurements are always nice, you could do a full series on antennae and how to use them.
The measurement of the TTGO antenna shows how your setup will influence the outcome. You should always test an antenna in a situation that resembles the actual use and mounting the antenna directly on the reflection bridge is not "actual use".
I have developed a number of commercial products with 433, 868 and 2450 MHz radio solutions and have done antenna measurements (and actual range measurements) with these products. Our first 868 design was measured with the antenna mounted on a wooden pole measuring both the reflection and the antenna radiation pattern. Surprisingly, the measurements were worse than the actual product's radiation pattern. I then suggested to mount a piece of PCB material and a battery near the antenna in the same way as the actual product has - this gave a complete different view of the antenna.
It looks like the TTGO 868 antenna was designed to be used on top of a large steel cabinet - a typical use case for a short range 868 telemetry application.
P.s: reflection measurement is only part of the antenna measurement - you also have to measure the (3D) radiation pattern. From a reflection point of view, a 50 ohm resistor is the best antenna ;-)
You are absolutely right, also with measuring the pattern. But this is not easy. If the SWR is bad, then a good pattern does not help a lot. And this is what happens with many Chinese antennas because they are sold for completely wrong frequencies.The patterns for similar antennas should be much more similar than the SWR is.
2 years ago and still the best video about LoRa!
Thank you!
3 years later, still interesting and very usefull. Thank you internet, thank you sir with the Swizz accent for your energy in making this video and doing such extensive researches
Glad it was helpful!
Once again, such GREAT information. I'm sad I hadn't found you earlier... would have saved me some headache.
Glad it was helpful!
Hi! Andreas I see your videos frecuenly and sorry by my bad english but the goal of Maradona is the best moment of my life!! It was the best moment of my life, it is too much to say that I am Argentine, hehe, the electronics and soccer are my passion, I live in Tierra del Fuego Argentina! a big greeting from here for you!!
Glad you liked the video about Maradona!
Another excellent video, lightyears ahead of anyone else. I see so much potential for these low power ESP32 Lora boards . .
Thanks!
Thanks very much for your summary. It shows that you need to be critical when choosing the right antenna.
True!
I junked the supplied HELTEC antenna in favour of a DIY 868MHz groundplane constructed on an SMA connector with brass rod radiator and radials (bent downwards by 45 degrees. I tuned using my on my SA starting with the radiating element slightly oversize and carefully clipping off tiny preces of the element until it resonated on 868. Far better.
Good idea!
This is a great video. It really shows some great investigation using tools that most of us mere mortals do not have access. The antenna results are truely staggering. Thanks for sharing!
You are welcome. The Spectrum Analyzer was a dream of young Andreas. So I bought me one when I became old ;-)
For me it was an oscilloscope. I'm not old enough for a tracking spectrum analyser just yet. :)
:-)
Super, thanks! Having the right tool for the job really does help. This confirms my experience with the Heltec helical antenna. Now time to find the post on TTN forum showing how to cut these and optimise a simple wire 868 antenna using a small piece of shield braid. Much obliged Andreas!
Or buy a better one...
thank you sir i was planning on getting one of these boards from ebay after watching your lora war driving video... now ill be getting a esp/hopefm setup and just doing the solder myself.
:-)
I was just looking at these a few days ago, thank you for this great analysis. I dream of a spectrum analyser but my wife would certainly kill me if i bring yet another huge expensive piece of lap equipment to my desk in the living room :)
She might be right, I have to admit ;-) This is not exactly a device for the living room and I had to get 60 till I got one.
I found this video when I was trying to figure out why I could barely communicate on 915MHz between two heltec boards on the same bench. I have the nasty helical spring antennas and now I know that they probably hardly couple anything into the ether! Just watching this video in advance would have set me on a path to getting some better boards and saved a lot of pain and anguish.
Still, such a small range might have a different reason (e.g. you got a 433MHz version). But maybe you try with standard TTGO boards I use in my newer projects. They work well.
@@AndreasSpiess I have some of the Lilygo boards on order -- they have the better antenna and I hope are general better all round! Thanks
Andreas, you are a neat guy, a man after my own heart! I love your videos, I have learned so much about Arduino and module applications, please keep up the GREAT WORK.
Thank you very much for your nice words! Comments like that are the diesel for creators like me ;-)
Thank you for sharing your vast knowledge and laboratory test equipment. Excellent !
:-)
Hi Andreas, thanks for the great videos. I hope this isn't a redundant comment but your channel has so many comments I can't find if this was updated( hey whose fault its that ;))
I recently bought some of the Heltec WiFi LoRa 32 (V2). They have a new antenna, I attached one to my crude AAI RF vector analyzer(N1201SA). On the antenna I tried it I can measure ~1.2 for VSWR at 915MHz and at 868MHz I measure ~2.1 for VSWR. You can tell the antenna is better it has a molded plastic sleeve over the antenna bit and when you try to squeeze it it is solid. The resonant frequency looks to be 935MHz with a VSWR of ~1.05. Yes my measurements are not as accurate as a lab instrument but good enough for the girls I go out with. Thanks.
Thanks for sharing your measurements. This is why I do not give recommendations on antennas. Suppliers change them fast. Here obviously towargs the good side...
awsome as usual Andi 👍🏻thx. i think these boards are great for preprototyping and development, no soldering, no worrying about power supply and so on, u can even ask the aliexpress supplier to solder the pins at no extra cost...
Thanks for the feedback
You ROCK DUDE, most intelligent thing I've heard on CZcams in a long time. Thank You
You are welcome!
Stop sitting on the fence, get down and tell us what you really mean! :) This is exactly the resource and review users, who do not have the advantage of your knowledge and equipment need. Well said.
Thanks. An thank you again for the nice evening in Amsterdam. I think I will contact Stuart. I have an idea of building a automatic antenna tester based on his principles. Maybe you can help me getting the contact?
No problem - we can IM anytime. He only lives a kilometer away from me. Look forward to it.
:-)
Excellent especially explaining antenna reflection and how that needs to be considered. (The Maradona reference made it even better. :) )
Thank you for your nice words!
I really enjoyed your video. Thanks again for your methodical, analytical approach to evaluating these boards. I've been an amateur radio operator for years and years, and while I have no formal EE education in antenna theory, I have come to appreciate the empirical evidence I've noticed over the years. The analog and RF aspects of some of these amazing products these days tend to get inadequate attention and consideration. Thanks for shining a light on these aspects. Perhaps the vendors will do a bit better in the future if they know that people are paying attention to this aspect of the product's quality.
I ordered a V2 version. We will see what they learned...
@@AndreasSpiess So, did they?
Thumbs up again. To the point and informative video on right time. I just received rfm95 modules and was thinking should I really spend time in making pcb and soldering. But now I believe I better do it :).
I have been discussing same issue of antennae compatibility with another youtuber Informatica1. I got info same as you, Do not Trust Antennae from Aexp or banggood etc. Thanks again.
Happy soldering. It is a fast job.
As for as measuring efficiency of LoRa antennas - I suppose the calibration should be made using calibrating blind BNC to IPX adapter. Than later you should test the whole assembly: BNC to IPX adapter IPX_CABLE_SMA SMA_LoRa antenna under test. I can guess the thin cable may change the whole fit of impedances between IC output and antenna. Of course I can not guess if it will be better or worse, but we should check it.
What you measured is just: spectrum analyzer output BNC to SMA adapter LoRa antenna. So you omitted quite significant influence of the thin connecting cable. You may tell you have a lot of experience and it is negligible :) I will answer - hats off, Master :)
In the end I am interested how much power tha antenna gets to transmit and how much is returned. I am not the designer of the PCB. He is interested in other things, of course.
@@AndreasSpiess I am discussing the IPX_CABLE_SMA cable, not PCB. We can assume if the PCB around LoRa chip is well designed there are no significant losses in path between LoRa chip and IPX socket.
But then there is a cable from IPX socket to the antenna - omitted in your test (5 cm @ almost 1 GHz).
And what if that cable moves resonance a bit? Making the whole efficiency better (I doubt) or worse - but it should be checked. Sorry Master, your method is not excellent, again, you made a great work but this point is not so good., no offence please. You have tools to test it.
For such measurements, you have to define a reference plane. And I defined my reference at the antenna. Of course, you can define your reference plane elsewhere.
Nicely done Mr Spiess. I hope Amsterdam was a lot of fun
Yes, it was. I was also in the „Flying Scotchman“ with a few Englishmen. If you know wat I mean ;-)
Well Played, well played! Maradona's mention makes my day!!! Great videos Sir.
Glad you enjoyed it!
I recently bought the Wemos TTGO Lora+ESP32 868MHz+Bluetooth+OLED from VNG Systems and tested it on the KPN LoRa network in the Netherlands, which worked fine for me. I think they have updated it, because the range was acceptable.
You see the difference of V2 if you look at the antenna position
Fantastic video yet again Andreas. Thank you so much for your continued great content!
You are welcome!
Yes. It is useful. Thank you for your great videos. Please continue to produce them. 😎
You are welcome
thanks sir, watching your channel is like attending classes ♥ with a good professor
You are welcome!
Thanks Andreas, you´ve saved me many hours of work and a box of aspirin pills. As soon as i receive my boards i´ll run similar analysis and share it.
I´ve got TTGO V 2.0 board, they said that some issues were corrected.
Thanks!
I will test the V2 board in one of the next videos.
Hi Andreas, You are a true champion and a masterful maker of the most beautiful, Fascinating and intellectually stimulating videos, there is so much Rubbish coming from China, from sellers who show nothing but Contempt for the rest of us Idiots who should know Better than to buy their absolute Rubbish !! Unfortunately...
a lot of people (myself included) fall for their false advertising and end up wasting our hard earned money.
If it was not for people like you making these masterful, life Enriching Videos, society and the CZcams community in general would be a very dull place.
Keep up the Great work!!!
Thank you for your feedback! It helps to keep me on track.
Thankyou for all your hard work investigating these boards. Your work inspires me onto greater and more challenging projects. Thankyou.
You are welcome. Enjoy your projects!
You really are a star Andreas, wonderfully detailed video, even allowing for the bad memories you brought back regarding the hand of God.
Thanks! I thought, the idea of a „unknown helping hand“ was similar to my experience;-)
Those antenna placements are ridiculous. Nylon mounting screws would help a little but you would probably get the best range by setting the boards on fire and using them to send smoke signals. Thanks for the testing.
:-)
XD
Outstanding. This is your strength.
Thank you!
Excellent analyse! Thank You, Andreas!
:-)
OMG!! What it's doing Maradona in your video!! From Argentina we also see all your excellent videos.
I thought, I did not understand why the antenna was much better with my hand than without. Similar to the 1986 situation.
Exactly my experiences with the chinese antennas. The only antenna I have that is actually an 868MHz antenna is the one from IMST.
When you touch your hand to the base of the antenna it becomes sort of a ground plane. My guess is that is why it changed characteristics.
A piece of copper wire cut to 1/4wave mounted in a SMA connector usually comes out better than the antennas that come with the boards.
I did some experiments with ground planes but was not very successful :-(
Sometime you have to put the toys away and seek a more professional solution, thus you can order some of the 800 MHz antennas for Motorola MTS2000 handhelds (the long ones, not the stubby's). They are fairly cheap and reliable just add an adapter (a sma male to sma male coupler I think is what it needs) if you need to. They should say Motorola 800MHz or 700/800MHz but they are pretty broad and cover 868 MHz.
I love seeing these antenna tests! Please do more!
The problem is that Chinese merchants change their supliers without anouncement. So my tests might not be relevant for you :-(
Another exceptional analysis. Thank you for sharing!
:-)
Excellent video, especially the part about the hand of God!!! The only problem is that the user of the board will need you to be there all the time holding the antenna in just the right manner to get good performance...
You are right.
really a quite excellent and informative video! thanks for posting it. I would love to see similar analysis of other boards such as M5Stack LoRa, and even possibly comparisons between libraries such as Sandeep Ministry and RadioHead.
M5 is here and will be covered. I might use the libraries mentioned in my videos (as I did in the past). But I do not plan a direct comparison.
Andreas, thank you for all of your nice videos.
In the meantime I bought 3 pcs. 433MHz Antennas from the antenna shop you proposed and linked in your comments.
From today I have the N1201SA antenna analyzer you also used in later videos. The antennas show resonance frequencies of 411, 429 and 433 MHz instead somewhere in the 433-435MHz interval.
So I would not recommend the shop you linked to any more.
All three antennas are ok, two are excellent compared with what you usually get. A few Mhz does not matter too much. Just touch something or move something around the antennas and the resonance will move much more than only 3 MHz. Maybe you have a look at the antennas I got with other modules. They were 200 MHz away :-(
Nice video. You’ve just saved me about 100 hours of my time because now I don’t need to research it. Thanks
:-)
Always good stuff and I enjoy your channel. It is an abundance of information, well done.
Thank you!
Andreas: great work, thanks a lot, this will be of help to my LoRa projects, for sure!
However, measuring these simple antennas without a proper ground plane and "free space" is skewing the results. As you demonstrated yourself by adding your hand as a makeshift ground plane: this alters the properties of the antenna dramatically. I think you should mount the antenna on a reasonably sized (bigger than wavelength) copper plate which would also shield it from your analyzer and make your measurements more reproducible.
Of course, such a ground plane should also be used later when the antenna is in production use.
You are right. But I think, we are not interested in how the antennas behave under good conditions, but on our devices. I never saw a sensor with a big ground plane ;-) I agree that my measurements are different from the real situation where the sensor is mounted somewhere.
BTW: I made a large ground plane to test the antennas. But this also did not provide reliable measurements.
But I think, if an antenna resonates at 500 MHz on my reflection bridge, the chance it resonates at 868 on the device is small.
Great video, i think the three different versions are because the non license frequencies of different countries can vary.
You are right.
Thanks for sharing 😀👍
As always, you are very good to check out all the best way to get to the point
Thank you!
I found that those annoying ham radio handheld whip antennas that TYT ships with their MD380 series HT's works great on the 433 MHz versions of those ESP devices.
Motorola MTS2000 HT 800MHz antennas with a male to male sma adapter also works well for the 868 MHz versions.
Thank you for sharing your experience!
Again another project of mine saved by Andreas thx
Glad the video helped!
Great and interesting ! This will be of help when I put up met LoRa gateway. Thnxs !
:-)
Another amazing video about LoRa!
Thanks!
Congratulations!!!!, and thanks... so one interesting option (taking into account the total cost and the emission power) would be esp-32 lora 433Mhz board, with a real (not fake) 433 mhz antenna. I think that really there isnt 868 boards, i think all ttgo boards have the same design and only change the antenna (they have seen that with default configuration 868 and 915 "works". As you can see, signal of 433 mhz is near 7db, almost like hope rfm95
This is what I thought at the beginning. But the 433 and 868 Heltec boards are clearly different
I am thinking in ttgo, heltec seems a crap all versions...
this was a great tour
1) what is an FCC approval?
2) the current HELTEC board looks different then the one the one in the video
You can google FCC
Yes, Heltec has new boards.
My HELTEC's modules have the rubber antenna like TTGO for lora and the helical one for WIFI ( the pcb antenna remains but used ) .Providing a simple ground plane for the lora antenna improved a bit the lora reach.
Mauro Cordioli same here. HELTEC with the rubber antenna, but I still had trouble connecting to a LoRa network. It is the 868 version and I made some chnages to the default scetch. What scatch/plug-in are you using?
These are the scatch modifications I used www.thethingsnetwork.org/forum/t/big-esp32-sx127x-topic-part-1/10247/24
I used a test sketch becaus I needed a constant signal, not a connection to a gateway
I have used the same thread as a guide, I have also reduced the number il bands scanned... I remember also that changing the power supply affected the stability of the board,may by there is some EMI issue, I do not have yet the time to check in deep that question.
thanks a lot ,you have knowledge and equipements for testing .
You are welcome.
Hallo Andreas (I am the guy from the Arduino Hannover LoRa Group)
This time I don’t agree with most of the video content, you have done much better investigations so far
The board energy usage measuring must be differentiated between the LoRa standby mode, and the LoRa receiving mode and the LoRa sending mode, this would allow users to get an idea about their device battery lifetime.
Antenna measuring, the Heltec 868 antenna I received was a 868 SMA antenna (black plastic outside, spinning wire inside). The problem with this antenna is that there is no ground plane, therefore it must be mounted on a metal peace to work. Unfortunately this is not documented by Heltec and other vendors. Your antenna measuring was also wrong because the metal peace is missing. There are other antennas which have this metal tube inside the antenna. So a proper measuring setup is needed.
BTW. On our own Arduino LoRa board (www.radioshuttle.de) we have this ground plane on our PCB, therefore this simple 868 MHz SMA Antenna works pretty good.
Frequency testing setup failure. You cannot specify a range for a 400 to 900 MHz to the SX1276 chip in software and start measuring. The SX1276 has two antenna input and output paths, called LF for up to 500 MHz, and HF for higher frequency, usually 868-915 MHz range, Usually the boards use only one output path LF or HF to the antenna. A total wrong measuring results occurs when when you are using a 433 MHz designed board specifying a 868 output frequency (or the opposite) you receive a crosstalk within the chip and the wires on the PCB which will give you total wrong results.
Regards from Hannover
PS: I like to talk to you about this an other LoRa ESP32 stuff, maybe we can have a privat phone talk about it.
1. I measured the antennas I got with the boards. And I did not get a PCB antenna.
I was in Amsterdam and did not see one sensor with an antenna setup other than mine. Non had a ground plane, all had just an antenna plugged into the devices. I think, an antenna has to be tuned for this purpose. And if everybody just plugs it into a device, it should have its best performance in this setup. Your approach with an integrated ground plane is probably a good idea for some antennas. If you watch Andrew's channel ( czcams.com/channels/HqwzhcFOsoFFh33Uy8rAgQ.html ) he uses many antennas which do not need an additional ground plane because they use the shield or a tube inside the rubber to build something like a dipole. If you add a ground plane to this type, they do not like it.
2. Thank you for the info about the two "channels". I did not know (I did not look into the datasheet). I assume these two "channels" explain the frequency gap I measured but did not understand.
The main goal of my scan was to understand if they sell us 433 MHz boards as 868 boards. If you look at my tests from this angle, they are probably useful. Or how would you have done them?
You saw that the two Heltec modules behaved completely different. So I was able to show that the hypothesis of selling us 433 Modules was wrong, at least for the Heltec ones. (I am not so sure about the TTGO).
With only one output connected to the antenna, it is not easy to understand why the output power at the antenna on both bands was very similar. A not connected wire usually does not transport this amount of power.
We for sure can talk about this stuff. I am on facebook messenger and twitter. There I can give you my Skype name
The 433 MHz Heltec versions uses the SX1278 chip which is specified only for 433 MHz but if you set 868 MHz has output, it works, but with totally wrong/bad results. The Semtech LoRa chip is under the display to review it’s variant.
The 868 MHz Heltec versions uses the SX1276 chip, this one can do 430 and 868 MHz, but only the 868 MHz (HF path) is connected.
For Heltec I am talking about the boards within a 6 month timeframe of my purchase, there have been also earlier versions with different hardware.
PS: I don’t think the Hope RFM95 modules for 868 and 915 MHz are any different, for export limitations into Europe is not allowed to import 915 MHz devices. The frequency is revered to some US military applications in Europe, therefore vendors specify modules and chips often with 868 or 915 MHz versions. I will check if I get a 915 MHz RFM module to measure the RFM95 HF output part list versus the 868 version.
Some time ago I ordered via Mouser a 915 MH STM FM Module, they rejected my order due to export restrictions by the US.
Habe kein Facebook und kein Skype, nur Google+ und E-Mail, kannst mich aber auch gerne im Büro anrufen.
On the SX1276 figure 6 schematic, it appears to be a balanced filter. The bottom components are the same as the respective parts on the top.
I did not look close to this filter. But some chips have balanced output which has to be matched to an unbalanced antenna
I just received some V1 TTGO Lora32 boards 868/915 versions and after watching this I tried both a 433MHz and a 968MHz sender/receiver sketch to see the difference, the antenna I received is a plastic 40mm SMA version, (no brand, 2 notches on the top) at 968MHz from one room to another I get -58dB at 968MHz and -131db at 433MHz. So it looks like 433 is simply not an option with some boards.
You have to buy a 433 MHz board if you want to use it for 433 MHz. As I showed they are different.
Excellent analysis, thank you for this
You are welcome!
Super. Hab mir nämlich gerade ein ttgo gekauft. Jetzt weiss ich wo ich dran bin. Vielen Dank Andreas.
Nicht tragisch. Einfach eine andere Antenne verwenden, wenn du eine Spirale kriegst
Excellent video yet again. Thankyou!
:-)
Very very useful! Thank you
Thank you!
6 years later and the Heltec Lora V3 boards still come with a useless mini coil antenna. I've ordered a 915 MHz antenna and hopefully I'll be able to contact someone with Meshtastic!
Let's hope!
I'm made my antenna using Hack RF one and GNU radio campanion, no necessary an expensive spectrum analizer for check!
Also a possibility. Thanks!
Amazing resource! Thank you! I've subscribed. I was wondering though, when will you review the version 2 of these boards?
Welcome aboard the channel. I know, I should do it...
I have some experience in antenna. But for the part concerning TTGO antenna testing, I think sth. Maybe misleading. Normally a long ferrite bead choke will be connected to the input of N-port when you test a wire antenna. Another way is to test the antenna mounted over a large thin metal board. Both will prevent the ground current flowing back to the test fixture. Your hand influenced the Return Loss result a lot, which makes clear that you should improve your test method.
Those cheap antenna especially TTGO one， may work fine if mounted properly on a flat metal surface in reality. Hope you can think about it.
You are right. But I am not sure if these sensors will be placed on properly designed metal surfaces. I used them as they are most probably used in reality. This channel is not a Ph.D. study, this is about reality ;-)
This was so useful to me! Thanks!
:-)
Thank you very much for these great advices
You are welcome!
As usual, perfect.
Nice, Very nice.
:-)
I just became a Patreon on your channel. Please consider pushing your Patreon info stronger at the tail end of your videos as I know there are a lot of people that need to contribute and benefit like I do. You may also want to consider creating a "Behind-The-Scenes" Video. Unless I missed that video already. Anyway. Please keep up the great work. I hope more people consider helping you out. -Da-Man from the Sunny Southern California, U.S.A.
Thank you for your support! I am an engineer and not a salesperson. Maybe this is why Patreon does not shine up too much. I was astonished that I got to where I am now in only 2 weeks of Patreon...
I think I did a "behind the scenes" video 2 weeks ago. And a lab tour about a year ago. What would you like to see in addition? Then I could maybe integrate it in the next "behind the scenes"
The simple reason for the thee different frequency range: BECAUSE OF THE FCC LAWS. The 433MHz for China/Asia, the 868MHz for Europe and the 915MHz for Canada.
I do not know if FCC has aleady something to say in China ;-)
@@AndreasSpiess hint: all the Chinese remote toy cars working on 433MHz 😉
It would be interesting to see what effect placing a four wire ground plane around the base of the final aerial on your test rig. I usually regard one as vital to remove any movement effect in the feeder.
I will include a GP in my antenna tests. I finished my test rig and did first outside tests today (we had a "springy" warm day here in the south ;-)
It would be so nice to see 433,868 and 915 external antenna tests. I'm looking for it and have no idea what to buy.
I left a link of a supplier which did not cheat me so far. So I assume, also his antennas on other frequencies are ok
Extremely useful. Thanks for that. But it left a hole, no discussion about RA-02 chip. Can you do a video about it with esp chip.
I assume that the RA-02 also use standard Semtech chips as all other boards. So there is not a lot to write about it for the moment.
Good to know. I was looking at these.
:-)
Hi. I have problems initializing the module “DollaTek LORA32 433Mhz ESP32 Sx1278”. It is a clone of the TGO LoRa32 SX1276 / 78 module. I cannot initialize it with the library . There are problems with the pins. However, I can initialize it with the
Unfortunately I cannot do remote debugging.
You made me laugh with the Maradona comparison 👍🏻😂
:-)
Danke vilmal für das würkli sehr interessanti Video. Thanks very much for this very interesting video. 👍🏼
You are welcome!
This looks like a great option to have an ESP32 send its GPS location to another ESP32 and have that one point a compass needle (on LCD) towards the sender. Having two work in tandem would allow each device to point to the other. Never losing friends in a crowd, concert or hiking.
Have you come across anything like this before?
Ive had a look online but not sure if i have been using the correct search terms to see if anyone has done this yet
Maybe easier done with an app on Smartphones? I think you can locate your friends there if all agree.
-great video, i was wondering is there a cheaper way to check antennas, if they are tuned for eg 868. Not that i dont want a spectrum analyser, but its a bit expensive :)
You are right! I just had a phone call to test a cheaper device (In the 100$ range). And I have some ideas for a very simple setup without any instruments. So stay tuned...
I was thinking about ESP32 for some remote monitoring, I think I'll give it a pass at the moment based on your findings, and wait until manufacturers have sorted things a bit better.
Maybe a good idea unless you do not need to bridge a big distance
Strange they ship useless antennas... Is there a trick or a cheap way for us non-blessed with expensive equipment to check various antennas and chose the best one ? For lora and for 2,4 Ghz
TheKetsa I think they probably only sell the boards, and the actual shop on AliExpress or ebay has no idea about antennas in general..
That is what I think, too
From my own experience: I was surprised to find the HELTEC modules had better reception range on 868MHz than RFM95 or RFM69 - this was using GFSK, not LoRa but would mean still the HELTEC RF circuit is not that bad.
Thanks for your feedback.
Excellent! As usually. Thanks!!!
Thanks
Excellent once again!
Thank you!
I have been using the TTGO 433 Mhz board with the supplied helical antenna and get what is at least for me very acceptable range - with one unit on my desk and the other laying on the front seat of my car I get good reception at well over 500m in a heavily built up area at SF7. I'm sure if I repositioned the antennae that could be improved. The ESP8266 antenna on my unit is a PCB design, not sure if this is because this is a clone or they just designed the layout differently for this version - everything else appears identical.
Thanks for the feedback.
Very useful!, Thanks Andreas!
You are welcome
detailed and professional analysis, many thanks.
Could you please carry out the same test to a Pycom LoPy board? it is similar priced compared with heltec board, but has semtech sx1272 chip on board and is shielded, has FCC approval.
I have one but was never able to get it running. So, for the moment no tests :-(