So we are building a house that needs a septic system installed, which involves sub-surface irrigation pipes, and a grass field that must be mowed regularly. (17metres x 18metres)
I want to build a lawn mower robot ;-) , to mow the lawn automatically. At this stage we are laying the sub surface irrigation pipes and I think it's a great opportunity to lay a cable in with the pipes. I have found some "direct burial" Cat 5 cable that I am thinking will work well if I connect all of the conductors together at the ends. It's gel filled, so it should last some time.
The question to the collective group here, is, how do I sense the cable?
I have an idea, but if you think I am waaay off, let me know.
I have an RF sniffer (cable finder) that I purchased from ebay which works well. It has a transmitter that connects to a cable, and a negative crocodile clip which you clip to earth. The receiver wand seems to just be a coil with a very high gain audio amplifier. If I wave it over a power line, I can hear the 50Hz hum. If I wave it over the RF transmitter, I hear a dual tone, and interestingly, if I wave it over an analog telephone line, I can hear the coversation!!! :0)
So I am thinking of sending a single DTMF tone over the "transmitter" and using a series of pickups in the robot, with DTMF receivers, to listen to the power line.
What do you think? Any better ways? I have not tried it under ground yet. I wonder if the ground itself will act like an earth and shield the signal, especially since its around 100m of cable.
It's got to be reliable of course, as I don't want it to drive away, hence I think the DTMF tone adds some reliability.
I could simply connect the two ends of the cable to an audio amplifier, that way it would make a large electromagnet. Probably easier to pick up than RF?
I want to build a lawn mower robot ;-) , to mow the lawn automatically. At this stage we are laying the sub surface irrigation pipes and I think it's a great opportunity to lay a cable in with the pipes. I have found some "direct burial" Cat 5 cable that I am thinking will work well if I connect all of the conductors together at the ends. It's gel filled, so it should last some time.
The question to the collective group here, is, how do I sense the cable?
I have an idea, but if you think I am waaay off, let me know.
I have an RF sniffer (cable finder) that I purchased from ebay which works well. It has a transmitter that connects to a cable, and a negative crocodile clip which you clip to earth. The receiver wand seems to just be a coil with a very high gain audio amplifier. If I wave it over a power line, I can hear the 50Hz hum. If I wave it over the RF transmitter, I hear a dual tone, and interestingly, if I wave it over an analog telephone line, I can hear the coversation!!! :0)
So I am thinking of sending a single DTMF tone over the "transmitter" and using a series of pickups in the robot, with DTMF receivers, to listen to the power line.
What do you think? Any better ways? I have not tried it under ground yet. I wonder if the ground itself will act like an earth and shield the signal, especially since its around 100m of cable.
It's got to be reliable of course, as I don't want it to drive away, hence I think the DTMF tone adds some reliability.
I could simply connect the two ends of the cable to an audio amplifier, that way it would make a large electromagnet. Probably easier to pick up than RF?