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Topic: JSN-SR04T long range ultrasonic wange finder Mininmum Range  (Read 3917 times) previous topic - next topic

npkamen

Just did a quick check and here is the image of what I've logged over the last two days.



Also the deviation was larger the second day vs the first.  The tank level is scaled 0-237cm=0-100%.  Sensor is mounted at 257cm from bottom and I've just taken 100% to be at minimum measuring distance for sensor.

npkamen

I think I may have found the source of the problem (or at least something that needs rectifying anyway).

I'm powering the arduino using the Vn pin with a 6v lantern battery and it just so happens that around the same time as the readings going a little haywire, the input voltage is dropping to below 5.5v.  This is too low for the nano regulator so I'm wondering if this is causing some issues.

I'll get a pair of lantern batteries tomorrow and see if that solves the problem (feed 12v into Vn instead).

teckel

I think I may have found the source of the problem (or at least something that needs rectifying anyway).

I'm powering the arduino using the Vn pin with a 6v lantern battery and it just so happens that around the same time as the readings going a little haywire, the input voltage is dropping to below 5.5v.  This is too low for the nano regulator so I'm wondering if this is causing some issues.

I'll get a pair of lantern batteries tomorrow and see if that solves the problem (feed 12v into Vn instead).
It would be odd that a marginal lower voltage would cause a reading like this.  But, it's worth a try.  I think I'd try a different sensor like a HC-SR04 instead first.  Or, try placing the sensor in a tube to try and avoid echos.

Tim
My hardware: Arduino, Teensy 2.0, Teensy 3.2 & custom ATmega328 systems
My libraries: NewPing, LCDBitmap, toneAC, toneAC2, NewTone, TimerFreeTone
My projects: http://www.DogBlocker.com/
My beer: Great Lakes Brewing Co. Lake Erie Monster

npkamen

It would be odd that a marginal lower voltage would cause a reading like this.  But, it's worth a try.  I think I'd try a different sensor like a HC-SR04 instead first.  Or, try placing the sensor in a tube to try and avoid echos.

Tim
Yes I was thinking the same.  But it does need fixing anyway so may as well give it a go first.

Unfortunately I can't use an HC-SR04 as it needs to be weatherproof (outdoor water tank).  If the bigger power supply doesn't help then I'll go for a stilling tube.  Does anyone know what the minimum diameter for a stilling tube is with one of these?  I only have a fairly small hole to put it through (<100mm).

npkamen

Well the input voltage was the issue.  Switched out the single 6V lantern battery for a pair wired in series and last night all went well.

The tank level sensor transmits its value back via a CC1101 radio to another nano and the RSSI of the signal back at base has improved dramatically as well (+10dBm).

I'm using cheap clone nanos and I wonder if the regulator isn't as good as the proper genuine one.  I'll have a look at the board and have a squiz at a datasheet to see what's what.

Will keep an eye on it over the coming weeks and see what happens.

ykoch

Have anybody tried to use the normal HC-SR04 board connected two JSN-SR04T unit? Does this solve the blind area?

dave-in-nj

a little late to the party.....

I have been trying to find how to interface to the raw sensor  :


but have only come to the point that the only information is on the module :

.

I found reference to a researcher who once had a site that detailed the interface to the modules that were specific to the GM standard.

it seems that the 2 wire sensor is both the ping and the receiver.
he said that they tried to get three sensors all timing aligned, then ping 2 and use the center as the receiver.

it seems that the HC-SR04, the hobby version with two heads, does exactly that.
it would also seem that if one could control the raw sensors, that one could use one as the transmitter and the other as the receiver.  that would eliminate the 20cm distance limit and bring it closer to the HC-SR04 sensing range.

makes me wonder if I could remove the transmitter and receiver and swap with two of the IP66 car sensors.

as a note, there is yet another sensor on E-bay that does 8 meters to 25cm
this one comes in a plastic housing with multiple options of how to get readings. digital or serial.
costs a bit more, but  could be used in some other uses such as a lake or river or tide pool......



dave-in-nj

Have anybody tried to use the normal HC-SR04 board connected two JSN-SR04T unit? Does this solve the blind area?

in reading about sensors. the auto industry has a black hole as far as information goes.
it seems that every car manufacturer uses a different buss, some low speed, some high, some half duplex... 
some parking sensors have a chip so the output is a pulse stream of some value.  some send the address and signal, some send the signal twice....  some are just simple sensors and the brains are in a remove board.
It seems that the cheap ones on e-bay are probably all of the same design.  I have not found a site that shows someone doing the dissection of one to see what it is made of.  if the cheap one is as you hope, a simple piezo transducer/receiver, then your hope of just removing the open sensors and swapping them with two waterproof ones would be a possibility.
might need some tuning for the pulse and such.

npkamen

Well I just did something stupid.

I wasn't thinking and accidentally put 12V onto the 5V pin of my sensor (and let the special smoke out).

Mine's a bit charred so can't see it easily but can somebody identify the chip next to the connector for me?  I'd like to have a go at replacing it if it is possible.  Mine's too charred to read the writing on the chip any more.

dave-in-nj

my HC-SR04 has 3 chips.  one says LM324
the other two are devoid of any marking, ink, etch, nothing.

I know that some e-bay sellers have photos of both sides, and you can enlarge to see chip numbers.....

but, I have found too often that chips from china are ground off to prevent identification

dave-in-nj

I just opened the end of the sensor.  this is the e-bay special parking sensor on a wire for $1.70 and free shipping.

it is a simple piezo device, in a housing that is aluminum and filed with a waterproof sealer.
that aluminum housing is then put into the plastic housing you install in the bumper.


dave-in-nj

Have anybody tried to use the normal HC-SR04 board connected two JSN-SR04T unit? Does this solve the blind area?

in my searching, it appears that the waterproof sensor has to have a rather large voltage ping to move the face of the aluminum housing.  the harmonics of the housing ringing and required damping of that prior to attempting to get a reading may be the result that there is a time lag.   time lag = minimum distance = blind  spot.  
if you look at the JSN boards, they have a couple caps and what looks like a tuneable part.   these may be used for that higher  power for the ping.
I ordered one of the JSN boards.  will report on what chips it has in a few weeks.

numbat

I'm sure that would be fine.  There's nothing special about the length of the cable (it's not an antenna).
Hi, this is my first post here, so welcome everybody.

I've bought JSN-SR04T sensor and becouse of short sensor wire I decided to extend for ~2 meter. But after soldering I found that sensor readings are not very accurate and readings are floating.

Original cable sensor gave me rock stable readings

The new cable I soldered is more less the same thickness as the original one. What should I do?
I found some potentiometer trim. Should I use it to calibrate with a new cable?

Edit: Once I soldered original cable again it started operate normally

Thanks for your response



numbat

Hi, this is my first post here, so welcome everybody.

I've bought JSN-SR04T sensor and becouse of short sensor wire I decided to extend for ~2 meter. But after soldering I found that sensor readings are not very accurate and readings are floating.

Original cable sensor gave me rock stable readings

The new cable I soldered is more less the same thickness as the original one. What should I do?
I found some potentiometer trim. Should I use it to calibrate with a new cable?

Edit: Once I soldered original cable again it started operate normally

Thanks for your response
I found solution. I brought good quality braided cable from my friend and now it works perfectly. I have repeatable readings.

HRodrigues

Thank you, Tim.

So to confirm, as soon as you provide power to the PCB, you also get the steady stream of pings (i.e., if you "listen" to the sensor, you hear it ticking quickly even with no TRIGGER signal being sent) as well as a fast-blinking red LED on the PCB?  Is that right?

I bought 4 of these PCB/sensor kits and they all act in the same way, so I'm hoping it's not a problem with all four of the PCBs/sensors.

Many thanks again.
Hi everyone.. This is my first post here so hello everyone.

can someone tell me how this sensor works?
I have the same problem and don't know if its a bad sensor..

thank's

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