RF emitter/receiver

Hello,
So I'm looking for RF receiver/transmitter that has TTL output and i can't know the direction/location of the emitter

i want to place the RF reciever in a drone, and i want the drone moves to the transmitter location ( i want to know the direction or the location of the transmitter taking in the account that the receiver is carried by the drone) can i use this pair for this purpose http://www.picaxe.com/Hardware/Add-on-Modules/433MHz-Radio-Transmitter-and-Receiver-Pair

if you any suggestion please let me know
To sum up, i want a RF pair that has TTL output and i can know the location of the emitter because the receiver will be in a drone

Hi,

Welcome to the forum. What you are attempting is certainly NOT EASY ! How do you intend that the "TTL" (digital) output would indicate the direction of the transmitter?

Basically, what you might need is THREE receivers with RSSI (Analogue, Received Signal Strength Indication) outputs and THREE directional antennas (for X, Y, Z axes). In principle, it's then possible to calculate the direction of the transmitter (i.e. from the relative signal strengths), but it's questionable if the PICaxe could calculate that fast enough (since you haven't told us how quickly or accurately the direction information needs to be updated).

Normally "SuperRegenerative" receivers (as in your link) are not recommended because they output "garbage" when there is no signal, but in your case the transmitter would need to operate "continuously". However, that is arguably not permitted on the 433 MHz (ISM) band, nor this band even legal in USA at all. Also, 433 MHz directional antennas might be too large for a Drone.

It would probably be better to use the 2.4 GHz band (WiFi, Bluetooth, etc.) and pay particular attention to the computational power required. Or use a totally different strategy, for example based on accelerometers and GPS positional information (assuming operation outdoors).

Cheers, Alan.

Hi,
so what i understood is that the RSSI can be used but its not accurate..

Can you suggest a RF pair that has TTL output and i can for example buy another device to know the location of the emitter (not 100% accurate but in high percentage)

What i want to do is to mimic the nuclear radiation, i got a conclusion than the RF can be used with some modification to act like the nuclear radiation. Do you think its a good idea to mimic the radiation by using RF ??

keep in mind the system should be in a drone (indoor condition)

BTW, your answer is very detailed, i really appricaite it thank you !

Indoors you can use IR.

How can i use IR for this purpose? can you please clarify more? and how is RF is related to IR?
Thank you

Hi,

Yes, I also was going to suggest Infra Red; there are many PICaxe projects that use it for "Robot" searching or collision avoidance, etc.. It's quite easy to work with, for example many digital cameras can "see" it, even though the human eye can't.

Basically: Radio, Infra Red, Visible Light, Ultra Violet, X-rays and "nuclear" radiation, etc. are all Electromagnetic waves, having different Frequencies (and wavelengths) and obey the "Inverse Square Law". Radio waves (like you first suggested) have the longest wavelength and thus require the largest "sensor" (antenna), but can pass through walls, etc.. "Near IR" behaves much like light so may not even pass through a sheet of paper. You may need to decide which characteristics will best simulate the radiation that you wish to emulate.

But there are also other possibilites such as "Far Infra Red" (heat which can be detected by a PIR detector) or perhaps even UltraSonics (sound), but this is NOT an Electromagnetic Wave.

Cheers, Alan.

One of the RF modules that gives a digital RSSI output can be used as a crude homing device, I have tried it with a RFM22B.

But its very crude, may just work in a flat open field, but in an area where there are buildings or vegitation there can be so many reflections that it wont work well at all.