I got a project upcoming and I had this idea to use the nRF24 PA 2db modules and
being lucky I can get up to 500 meters without problem but from my last tests using
same ground lvl nRF's they don't get like constant signal the signal breaks sometimes.
So the idea is to put 2 nRF's in parallel as transmitters so I can boost more the
signal, is that possible?
If not how else can I boost my signal?
Thanks.
D.60
Hi,
Two Tx, will not boost your signal, in fact two Tx and aerials will produce a radiation pattern of maxima and minima.
And forget about feeding two Tx into one aerial, unless you can sync the RF, which is highly unlikely.
There are regulations about the ERP of these wifi and tx/rx devices.
Tom... 
What about sending with 2 nRF's same data but instead of sync them just write a small
algorithm which will say like :
nRF1 send a package then nRF2 send other package and so on... etc
sending like 400 packages per minute and per module, and only 1 package per module at a time.
In this way 2 modules will work the rage will be more covered.
D.60
Hi,
Sorry, but ERP is the only way you will get range, an aerial that has some gain will help.
Did you google
nrf24l01 increasing range
Tom...
I suspect if you try to send the same message with two nRF24s at the same time they will operate slightly out of sync and cancel each other out - or just completely garble the signal.
...R
Have you looked at these with the antenna?
http://yourduino.com/sunshop//index.php?l=product_detail&p=191
Not nrf 24 but according to reviews a tested capability range of 1500m. 5usd is reasonable price.
There are several things to consider to try and improve the range of the nRF24L01+ modules. This covers most of them but a starting list is below.
Lower data rate.
Smaller packet size.
Different channel.
Better aerial.
Better PSU.
Shielding of the module.
so, 5 km would be a tad better than your results ?
Guys I already saw all what you send me, I'm not searching for a nRF to improve range
what I'm trying to do is to increase the packages and the signal.
and yes I already got a PA modue, get to 250kbps, high power and up to 500pks / sec
For example:
If I use a remote control car and have a single nRF the car maybe will go 300~ meters after that lose the signal at ground lvl but if I add 2 nRF's in paralel the signal in that zone will travel in different angles and
maybe improve my signal and go up to 500~meters.
The point of using 2 nRF is to have 2 antennas and 2 signals going, instead of 500packets per s.
1000 packets per s.
I done some test in open area and having a single nRF you need to put the antenna in a specific angle
and direction / away from obstacles to work but if I had like 2 antennas I would have 2 angels 2 traveling
paths of data in that way maybe (in theory) the packages will arrive the final destination.
D.60
Hi,
If you are going to use 2tx and 1rx, you will have some classic physics experiments concerning interference patterns.
If you have 2tx one tx transmitting one at a time, then thats the same as one on all the time.
Your packets will be different from each tx if you use two and the rx will not be able to sync.
I think you have some R&D to do.
First on how PACKET tx/rx works.
Second if you have both tx transmitting at the same time but putting packets on them alternately, you will have a pair of tx carriers. You need to look up how RF patterns work with more than one tx. You get areas of minimum signal and maximum signal due to phase.
Even having two Rx and them on different frequencies will not fix your range problem.
You need ERP, that is gain aerial, unfortunately as you increase aerial gain you decrease the angle of radiation.
Tom...
Domino60:
but if I add 2 nRF's in paralel the signal in that zone will travel in different angles and
maybe improve my signal and go up to 500~meters.
If you need proof that that can't work get a friend and two guitars with a string on each tuned to the same frequency as closely as you can and then pluck the two strings at the same time.
...R
Robin2:
If you need proof that that can't work get a friend and two guitars with a string on each tuned to the same frequency as closely as you can and then pluck the two strings at the same time....R
instead of trying to use one signal What if he had two data streams ? compare the serial data and use timing to fill in the blanks when one signal is lost ?
Domino60:
Guys I already saw all what you send me, I'm not searching for a nRF to improve range
what I'm trying to do is to increase the packages and the signal.
No mention of increasing payload size in the first post so why don't you tell us now what size of payload your wanting to transmit and how often.If I use a remote control car and have a single nRF the car maybe will go 300~ meters after that lose the signal at ground lvl but if I add 2 nRF's in paralel the signal in that zone will travel in different angles and
maybe improve my signal and go up to 500~meters.
Why not stick with one transmitter but connect the receiver to diverse antennas if your worried signal polarisation is changing the range.The point of using 2 nRF is to have 2 antennas and 2 signals going, instead of 500packets per s.
1000 packets per s.
Do you really need that many packets of data per second?I done some test in open area and having a single nRF you need to put the antenna in a specific angle
and direction / away from obstacles to work but if I had like 2 antennas I would have 2 angels 2 traveling
paths of data in that way maybe (in theory) the packages will arrive the final destination.
As your controlling a car you should be able to ensure the antenna is vertical/horizontal so all you then need is to ensure the transmitter antenna matches the car antenna polarity.
My point is not to transmit at the same time with both TX but one a time.
Using the guitar string as example, each sound will travel on it's own road and there will be
a better sound because the sound is double more (data).
As dave said if I transmit 500 packets per module a second and some of them are lost, the other
TX will add the extra data/packets in a different angle and will never be lost.
as example the 2~3db antenna looks like that.
Info link: https://rcexplorer.se/projects/2009/06/understanding-antenna-gain/
If i build for example a airplane or quadcopter instead of RC car and have at my controller
just a single antenna in the vertical axes as you can see at 90 degrees the signal will be lost
or i will get instead of 500 packets i will get like 100~50, if I put 2 antennas on my controller
one vertical position and one horizontal i will get full 360 and no packets lost.
Thats what im trying to say.
D.60
dave-in-nj:
instead of trying to use one signal What if he had two data streams ? compare the serial data and use timing to fill in the blanks when one signal is lost ?
The nRF24 has error checking and can be set to resend up to 15 times so I can't see any value in a second data stream.
Looking at Reply #14 I'm not really clear what you are thinking of doing.
If your concern is that the orientation of the TX antenna may be poor relative to the position of the Rx device at a particular time then maybe it would help to have two TX nRF24s at different orientations and send the same message from both one after the other - but NOT at the same time - in the hope that one of the messages gets received (and assuming it does not matter if they are both received).
I did a test with a pair of nRF24s with the PCB antenna and at a range of 110m it did not seem to matter how I oriented the hand-held TX device.
...R
This is my exactly 1st line at Reply #14
My point is not to transmit at the same time with both TX but one a time.
send the same message from both one after the other - but NOT at the same time
I did a test with a pair of nRF24s with the PCB antenna and at a range of 110m it did not seem to matter how I oriented the hand-held TX device.
I did the same test and i got like 130 if i remember well, it really mater how you hold the antenna (pcb one)
Let me explain in more details what I'm trying to do:
I'M NOT TRYING TO SEND AT THE SAME TIME with both nRF tx's , I am not sending a specific message
a RC car will not accept a resended package because it's not something you need to resend but you need
to keep sending same new and new data not the old one.
I got 2 TX, and I send only one package a time per transmitter, using 2x atmega chips connected thru I2C
I combine the nRF's to transmit both one package a time not both in the same time.
The point of that is to have 2 transmitters in different angles as I posted pictures in Reply #14 to get a fully
360 cover, In my tests I found out that holding the antenna angle it really matters.
D.60
Domino60:
I'M NOT TRYING TO SEND AT THE SAME TIME with both nRF tx's ,
I don't think I am the only person who thought you were trying to send from both at the same time,
I am not sending a specific message a RC car will not accept a resended package
I don't understand that. Why won't it accept a re-sent package? What happens if it receives a re-sent package? Why can't you program it so that it can accept multiple copies of the same message.
because it's not something you need to resend but you need to keep sending same new and new data not the old one.
I don't understand this. If you never resend a message how can the receiver ever receive it if reception conditions are difficult.
I got 2 TX, and I send only one package a time per transmitter, using 2x atmega chips connected thru I2C I combine the nRF's to transmit both one package a time not both in the same time.
Why can't you put the two nRF24s on the same Arduino? Wouldn't that make the programming much simpler?
Developing and debugging wireless systems can be very tiresome. I find it very useful to write an essay for myself that describes the process in detail. For me that makes it clearer when I have overlooked some important feature or when I am making silly assumptions about the sequence of things.
IMHO it is also important to write code that does something that can be verified easily, and to develop things step by step. I know of no method to design a system that will automatically work in difficult circumstances - it needs to be tested and verified. I do understand that that can be difficult for long range communication.
...R
You're effectively creating antenna diversity with that approach. Theres some validity to it, but its usually better at the RX side.
I havent looked in detail at the NRF stuff, but usually you'll see best benefit with this sort of application by;
A quick google suggests lowering the data rate has significant benefits.
I don't understand that. Why won't it accept a re-sent package? What happens if it receives a re-sent package? Why can't you program it so that it can accept multiple copies of the same message.
It's not like I can't but controlling a RC car you need only to send packaged, if you lose packages in the way and try to resend them the car will go crazy 
Why can't you put the two nRF24s on the same Arduino? Wouldn't that make the programming much simpler?
I think it would be easier to put them with their own atmegas and send packages.
Scrumfled,
I understand what you mean I try to make a fully 360 communication, I got 2db antennas.