Which is easier to track the direction of the object?

[sk001]

I currently met a problem, I need to use a microcontroller to find the direction of the target in a small range ( <=20 meters ), laser and ultrasound do not work, think of the following methods
1. Make the target as a signal source, and the two antennas of the receiver judge the Angle according to the difference of the signal arrival time.
2. Only one antenna on receiver, and the receiver rotates to find the strongest Angle of the signal.
3. Same as 2, but add a 'shielding surface' to find the two places where the signal disappears to judge the target location
Which plan is easier to achieve?

 

[ZipZapOuch]

Which plan is easier to achieve?

I think I'm missing something - did you describe the target (size, material, color, flat vs 3D), shape, reflectivity of surface,...). . And did you describe "direction"? Direction can mean, direction relative to the viewer, or, if the target is moving, the direction of the movement.

Also, is the target completely autonomous from the sensor or can items be applied to the target, or wires run from target to sensor?

 

[sk001]

I think I'm missing something - did you describe the target (size, material, color, flat vs 3D), shape, reflectivity of surface,...). . And did you describe "direction"? Direction can mean, direction relative to the viewer, or, if the target is moving, the direction of the movement.

Also, is the target completely autonomous from the sensor or can items be applied to the target, or wires run from target to sensor?

I apologize for my lack of detail.
The target object can be anything that a human can carry, you can imagine something like an AirTag, and I want my thing to be always facing the moving target.
The target is completely autonomous. When the target is in the range the system can start tracking.
If I'm still unclear, please check out this video:
Autonomous Homing Robot (Radio Direction Finding)

I don't need wheels in this video, I just want it 'pointing' the target.

 

[rjenkinsgb]

What country are you in & what forms of transmission (frequency, power & duty cycle) are legal?

(There is no point suggesting things which are not legal where you are, and users on here will not help you break or ignore laws).

With the target object be visible or concealed?

 

[ZipZapOuch]

I apologize for my lack of detail.
The target object can be anything that a human can carry, you can imagine something like an AirTag, and I want my thing to be always facing the moving target.
The target is completely autonomous. When the target is in the range the system can start tracking.
If I'm still unclear, please check out this video:
Autonomous Homing Robot (Radio Direction Finding)

I don't need wheels in this video, I just want it 'pointing' the target.

So, which frequency will your target be emitting (like in the video you posted). If it is not emitting anything, you need to be much, much more clear on EXACTLY what you want to do. Please answer ALL of the clarification questions in my previous post.

 

[sk001]

What country are you in & what forms of transmission (frequency, power & duty cycle) are legal?

(There is no point suggesting things which are not legal where you are, and users on here will not help you break or ignore laws).

With the target object be visible or concealed?

I am in Hong Kong, China, I found on the Internet this: 409.7500MHz - 409.9875MHz, a total of 20 channels, each channel is 0.0125MHz apart, and only within 0.5W can be legally used.

Thank you for your kind reminder. I will abide by relevant laws very much, but I do not plan to make this device in the near future, I am just making a plan, and when I confirm the plan, I will learn related technologies and laws, and I will be extra careful at that time.

 

[camerart]

I currently met a problem, I need to use a microcontroller to find the direction of the target in a small range ( <=20 meters ), laser and ultrasound do not work, think of the following methods
1. Make the target as a signal source, and the two antennas of the receiver judge the Angle according to the difference of the signal arrival time.
2. Only one antenna on receiver, and the receiver rotates to find the strongest Angle of the signal.
3. Same as 2, but add a 'shielding surface' to find the two places where the signal disappears to judge the target location
Which plan is easier to achieve?

Hi S,
If you add a GPS module to the target, and send it's location, the receiver will be able to locate it.
Is this suitable?
C.

 

[sk001]

Hi S,
If you add a GPS module to the target, and send it's location, the receiver will be able to locate it.
Is this suitable?
C.

Hi C,
Thank you for your answer. I'm sorry it's not suitable, Because the distance between the target and the receiver is so close ( less than 20 meters ), the GPS error is too large.
S.

 

[rjenkinsgb]

If you add a GPS module to the target, and send it's location, the receiver will be able to locate it.

If you amend that to "A GPS with RTK" - then that would work very precisely, if the item was outdoors.

RTK gives accuracy in the centimetre range.



At around 400 MHz, a small pseudo "Doppler direction finder" is very practical.
There are numerous designs around, using two or four antennas.

The principal is that you use simple logic or an MCU plus diode switches to cycle through the antennas at audio frequency, a few hundred hertz.

The changing distance between "the antenna" (in use at each instant) and the target gives an audio tone through an FM receiver. The phase of that audio tone gives the direction to the transmitter.

Example design here:

What’s a (pseudo-) Doppler RDF

Doppler shift: First, let’s get to understand what Doppler shift is. Everybody knows of the pitch change of a fast moving object, like a passing car. The motor or horn sound of a car at const…

radiodirectionfinding.wordpress.com

 

[sk001]

If you amend that to "A GPS with RTK" - then that would work very precisely, if the item was outdoors.

RTK gives accuracy in the centimetre range.



At around 400 MHz, a small pseudo "Doppler direction finder" is very practical.
There are numerous designs around, using two or four antennas.

The principal is that you use simple logic or an MCU plus diode switches to cycle through the antennas at audio frequency, a few hundred hertz.

The changing distance between "the antenna" (in use at each instant) and the target gives an audio tone through an FM receiver. The phase of that audio tone gives the direction to the transmitter.

Example design here:

What’s a (pseudo-) Doppler RDF

Doppler shift: First, let’s get to understand what Doppler shift is. Everybody knows of the pitch change of a fast moving object, like a passing car. The motor or horn sound of a car at const…

radiodirectionfinding.wordpress.com

Thank you! I'll read it carefully.

 

[camerart]

If you amend that to "A GPS with RTK" - then that would work very precisely, if the item was outdoors.

RTK gives accuracy in the centimetre range.



At around 400 MHz, a small pseudo "Doppler direction finder" is very practical.
There are numerous designs around, using two or four antennas.

The principal is that you use simple logic or an MCU plus diode switches to cycle through the antennas at audio frequency, a few hundred hertz.

The changing distance between "the antenna" (in use at each instant) and the target gives an audio tone through an FM receiver. The phase of that audio tone gives the direction to the transmitter.

Example design here:

What’s a (pseudo-) Doppler RDF

Doppler shift: First, let’s get to understand what Doppler shift is. Everybody knows of the pitch change of a fast moving object, like a passing car. The motor or horn sound of a car at const…

radiodirectionfinding.wordpress.com

Hi R,
For my project I suffer from inaccuracy, I think the RTK type are expensive, is this correct?
C

 

[rjenkinsgb]

I think the RTK type are expensive, is this correct?

Yes, they are - they seem to have increased in price a lot since I got the ones I use...
It looks like near $200 now for any name-brand module...

 

[ZipZapOuch]

Hi R,
For my project I suffer from inaccuracy, I think the RTK type are expensive, is this correct?
C

It depends on your definition of "expensive" and the contribution it makes to the problem it solves.

 

[camerart]

It depends on your definition of "expensive" and the contribution it makes to the problem it solves.

Hi Z and R,
True, but this is why I'm holding back, as last time I looked the were £250, and when 4x are needed it all adds up.
I'll look again, once I come to the accuracy prolem with my project.
C