Imagine 2 nRF24 modules sending data packages between themselves.
One of the NRF25 modules is moving vertically in 3-5 cm steps (in rest when sending package, not moving).
Is it possible to measure the time difference between one data package sent from position A and a data package sent from position B, when the difference between the distance is 3-5cm vertically?
Take a look at the picture for further details. Thanks a lot for feedback
3xdamag3:
Is it possible to measure the time difference between one data package sent from position A and a data package sent from position B, when the difference between the distance is 3-5cm vertically?
How much time will it take for the radio signal, that is the data package, to travel 3cm ?
What would you use to measure that time? It's called "propagation delay".
Paul
srnet:
How much time will it take for the radio signal, that is the data package, to travel 3cm ?
I want to first map the position of the other nRF24 (B) that is changing its position in a defined row as shown in the picture.
Pasteboard - Uploaded Image (picture)
3xdamag3:
I want to first map the position of the other nRF24 (B) that is changing its position in a defined row as shown in the picture.
Then come back an ask questions when you have done that.
Is it possible to measure the time difference between one data package sent from position A and a data package sent from position B, when the difference between the distance is 3-5cm vertically?
Not with hobby equipment.
Are you wanting to measure the RF signal time or the modulation/demodulation of the encoded message time? The RF travels at the speed of light. No need to measure it. The modulation of that RF is time related and the time is related to the modulation rate and that we don't know because you have not identified what you are using.
Paul
You will get better answers if you are prepared to explain what the project really is, its purpose and real world application.
Paul_KD7HB:
Are you wanting to measure the RF signal time or the modulation/demodulation of the encoded message time? The RF travels at the speed of light. No need to measure it. The modulation of that RF is time related and the time is related to the modulation rate and that we don't know because you have not identified what you are using.
Paul
I want to measure "the distance" from one device (A) to another device ( B) by using an RF signal. Calculating the distance(cm) in itself is not relevant for this purpose. The goal is to 1.) map the possible row-positions by moving deviceB one step at a time in order and let device A save the positions. 2.) when the mapping application is done then device A should be able to track the position of device B based on the mapping.
here is a picture of the physical world: Unknown-5 - Google Drive
When posting links to images, can you make sure they are publically accessible.
srnet:
When posting links to images, can you make sure they are publically accessible.
Sorry, try now.
Quote from: 3xdamag3 Thu Mar 11 2021 09:10:19 GMT+0000 (Greenwich Mean Time)
I want to measure "the distance" from one device (A) to another device ( B) by using an RF signal.
I dont see how that is possible at those distances, unless you have a very large budget.
Calculating the distance(cm) in itself is not relevant for this purpose.
Thats just your opinion, but then remember you dont know how to do it.
It seems to me the real purpose of what you are trying to do is very likely to be relavent.
Remember that forum members are volunteers.
Good luck.
srnet:
I dont see how that is possible at those distances, unless you have a very large budget.Thats just your opinion, but then remember you dont know how to do it.
It seems to me the real purpose of what you are trying to do is very likely to be relavent.
Remember that forum members are volunteers.
Good luck.
For my application, the distance is not something I need. If thats the case from a technical perspective in regards to the calculations, that's something else. I'm just telling you what the goal of the project is. Thinking it might make it easy for you to help me with some answers. But it seems you dont give a f about answering me and give me some guidance.
I do not understand the attitude you have in your comments. I'm just asking questions, it's also up to you to answer or not. You have done nothing but be difficult in your answers. You have not tried to understand my question or the problem. I have explained quite clearly and drawn two different pictures to further explain.. The fact that you have no answers, means have nothing to say about this subject. So dont just pick my words and make it difficult. It is voluntary to answer. When I can help others I help others if I have the answer/solution to their problem. In you case, you have no solution or have the knowledge to actually give constructive feedback.
Don't get so upset. You have never told us HOW and with WHAT you expect to be be able to do the measurements. So the simple answer is "yes it is possible to measure the time. IT is ALWAYS possible to measure things.
Paul
Paul_KD7HB:
Don't get so upset. You have never told us HOW and with WHAT you expect to be be able to do the measurements. So the simple answer is "yes it is possible to measure the time. IT is ALWAYS possible to measure things.
Paul
One idea I have is to use an Arduino nano + nrf2401 on Device A and the same for device B. But a friend of mine told me it might not be possible to detect any time delay for a distance differential of 3-5 cm with nrf24 modules. Then my question is how can detect timedelay if Device B changes a position by 3-5 cm.
An Arduino Nano runs at 16MHz. That means in the shortest amount of time (1 clock cycle) the Arduino can differentiate light travels almost 20m. In practice time differences need to be much larger than 1 clock cycle to be differentiated. You need to convert the incoming signal from analog, filter out noise and compensate for all kinds of errors.
So, no with the equipment you have chosen you will not be able to measure time difference between one data package sent from position A and a data package sent from position B.
If you tell the forum what the application goal is e.g., measure the size of a room, measure the distance between two toys, ... not what you think the implementation should look like, you likely get a lot more useful answers e.g., what type of sensors, Arduinos and or modules are usually used for this.
3xdamag3:
One idea I have is to use an Arduino nano + nrf2401 on Device A and the same for device B. But a friend of mine told me it might not be possible to detect any time delay for a distance differential of 3-5 cm with nrf24 modules. Then my question is how can detect timedelay if Device B changes a position by 3-5 cm.
You cannot use the devices themselves to measure what they are doing. You need something some other device/devices with capability of measuring nano second or smaller time intervals. Then you need to modify the nRF2401 to tell the measuring instrument when a transmission is started. And you need to modify the receiving device to tell the measuring device when the first bit of the transmission is received. Then move the sending device and measure the time again.
Are you willing to invest in the device/devices necessary to do the timing?
Paul
Paul_KD7HB:
You cannot use the devices themselves to measure what they are doing. You need something some other device/devices with capability of measuring nano second or smaller time intervals. Then you need to modify the nRF2401 to tell the measuring instrument when a transmission is started. And you need to modify the receiving device to tell the measuring device when the first bit of the transmission is received. Then move the sending device and measure the time again.
Are you willing to invest in the device/devices necessary to do the timing?
Paul
Thanks a lot, Paul, you answer now sounds very logical to me now. Yes, I'm interested in investing in the device necessary, if you have something in mind I would love to know. I'm also checking out the possibilities with BLE (RSSI measurement) and RFID.
Klaus_K:
An Arduino Nano runs at 16MHz. That means in the shortest amount of time (1 clock cycle) the Arduino can differentiate light travels almost 20m. In practice time differences need to be much larger than 1 clock cycle to be differentiated. You need to convert the incoming signal from analog, filter out noise and compensate for all kinds of errors.So, no with the equipment you have chosen you will not be able to measure time difference between one data package sent from position A and a data package sent from position B.
If you tell the forum what the application goal is e.g., measure the size of a room, measure the distance between two toys, ... not what you think the implementation should look like, you likely get a lot more useful answers e.g., what type of sensors, Arduinos and or modules are usually used for this.
Can you recommend other equipment so that you think might do the work?
All I can share is that there will be up to 30 steps with 3-5 cm between them, the maximum distance for sep nr 30 will be around 50cm from the device fixed.
Then my question is how can detect timedelay if Device B changes a position by 3-5 cm.
Again, not with hobby equipment. See reply #5.
A tape measure can be used to measure distances between objects, and the time for transmission can be calculated. Divide the distance by the speed of light, 3x1010 cm/sec.
