Maker Pro
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How to detect the transmitter frequency ?

R

Rodo

Jan 1, 1970
0
Hi all,

We have a Tx/Rx system at work that measures water level in a huge tank. The
system works but all the documentation got lost somehow. I tried to open
the Tx and Rx modules to see the parts inside but they are potted solid. I
need to document the system because the info is missing and the design
engineer left a few years back. Is there an easy way to detect the
transmitter frequency ?

We don't have any fancy spectrum analyzer but we have a scanner (scope and
the like). I tried a few of the common freqs (900, 315, 310, 433MHz, etc)
but I couldn't find it (I was told is below 900MHz). If the Tx has shifted a
bit I could be close but .... well ... the possibilities are endless so ...
I wonder if there is an easier way ?

Thanks
 
D

DaveM

Jan 1, 1970
0
Rodo said:
Hi all,

We have a Tx/Rx system at work that measures water level in a huge tank. The
system works but all the documentation got lost somehow. I tried to open the
Tx and Rx modules to see the parts inside but they are potted solid. I need to
document the system because the info is missing and the design engineer left a
few years back. Is there an easy way to detect the transmitter frequency ?

We don't have any fancy spectrum analyzer but we have a scanner (scope and the
like). I tried a few of the common freqs (900, 315, 310, 433MHz, etc) but I
couldn't find it (I was told is below 900MHz). If the Tx has shifted a bit I
could be close but .... well ... the possibilities are endless so ... I
wonder if there is an easier way ?

Thanks

Assuming that the Tx power is in the milliwatt range, just connect the antenna
to the input of a sensitive frequency counter.
No antenna lead? Get a smallish coil of a few tens of uH and place it in close
proximity to the Tx module. Connect the coil leads to the counter input. You
might have to play with position and orientation of the coil, but it should give
you a solid count somewhere around the module.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Life is like a roll of toilet paper; the closer to the end, the faster it goes.
 
A

Anthony Fremont

Jan 1, 1970
0
Rodo said:
Hi all,

We have a Tx/Rx system at work that measures water level in a huge
tank. The system works but all the documentation got lost somehow. I
tried to open the Tx and Rx modules to see the parts inside but they
are potted solid. I need to document the system because the info is
missing and the design engineer left a few years back. Is there an
easy way to detect the transmitter frequency ?

We don't have any fancy spectrum analyzer but we have a scanner
(scope and the like). I tried a few of the common freqs (900, 315,
310, 433MHz, etc) but I couldn't find it (I was told is below
900MHz). If the Tx has shifted a bit I could be close but .... well
... the possibilities are endless so ... I wonder if there is an
easier way ?

Something like this:
http://www.valuetronics.com/Details.aspx?ProdID=2888&Model=BK Precision_103
 
P

Phil Allison

Jan 1, 1970
0
"DaveM"
Assuming that the Tx power is in the milliwatt range, just connect the
antenna to the input of a sensitive frequency counter.



** Shame if the RF signal is pulsed or out of range of the counter ....




....... Phil
 
J

Jim Yanik

Jan 1, 1970
0
Assuming that the Tx power is in the milliwatt range, just connect the
antenna to the input of a sensitive frequency counter.
No antenna lead? Get a smallish coil of a few tens of uH and place it
in close proximity to the Tx module. Connect the coil leads to the
counter input. You might have to play with position and orientation
of the coil, but it should give you a solid count somewhere around the
module.

Or use a spectrum analyzer and antenna.
Optoelectronics used to make low-cost receiver/counters for this sort of
thing;are they still in business?
 
R

Rodo

Jan 1, 1970
0
I'm sorry I didn't make it clear that the Tx/Rx modules are not the one
reading the water level. That system is an ultrasonic meter. The Tx/Rx
modules are connected to the output of the ultrasonic meter and transmit the
info to the base unit.
Someone suggested a BK Precision counter. This sounds like a pretty good
option. I think the model 106 will need to be because I'm almost certain the
info is digital (on-off stuff)

Thanks
 
P

Phil Allison

Jan 1, 1970
0
"Rodo"
I'm sorry I didn't make it clear that the Tx/Rx modules are not the one
reading the water level.

** NO - you posted the opposite in fact:

" We have a Tx/Rx system at work that measures water level in a huge tank. "

Top posting Dickhead !


That system is an ultrasonic meter. The Tx/Rx modules are connected to the
output of the ultrasonic meter and transmit the info to the base unit.
Someone suggested a BK Precision counter. This sounds like a pretty good
option. I think the model 106 will need to be because I'm almost certain
the info is digital (on-off stuff)


** Counters cannot count what is not there.

A transmission must be * 100% continuous * to use a counter obtain the
frequency.

A radio scanner is still your best, low cost bet.



....... Phil
 
H

Homer J Simpson

Jan 1, 1970
0
Rodo said:
We have a Tx/Rx system at work that measures water level in a huge tank.
The system works but all the documentation got lost somehow. I tried to
open the Tx and Rx modules to see the parts inside but they are potted
solid. I need to document the system because the info is missing and the
design engineer left a few years back. Is there an easy way to detect the
transmitter frequency ?

We don't have any fancy spectrum analyzer but we have a scanner (scope and
the like). I tried a few of the common freqs (900, 315, 310, 433MHz, etc)
but I couldn't find it (I was told is below 900MHz). If the Tx has shifted
a bit I could be close but .... well ... the possibilities are endless so
... I wonder if there is an easier way ?

ISTR there's a way to use a grid dip meter to get close.
 
Hi all,

We have a Tx/Rx system at work that measures water level in a huge tank. The
system works but all the documentation got lost somehow. I tried to open
the Tx and Rx modules to see the parts inside but they are potted solid. I
need to document the system because the info is missing and the design
engineer left a few years back.

This may not be an engineering issue. If you cannot guarantee that
you can reverse-engineer the mfgr's specs _including safety margins_,
whose ass is on the line if the system goes tits-up and the tank
fails; just yours, or the owner's?

I know it sounds like a fun problem, but the phrase "CYA, remove and
replace" exists for a reason.


Mark L. Fergerson
 
A

Anthony Fremont

Jan 1, 1970
0
Phil said:
"Rodo"


** NO - you posted the opposite in fact:

" We have a Tx/Rx system at work that measures water level in a huge
tank. "
Top posting Dickhead !

It's not his fault you misunderstood him. The rest of us didn't have that
problem.
** Counters cannot count what is not there.

A transmission must be * 100% continuous * to use a counter obtain
the frequency.


You are wrong. The B&K 106 only needs a 250uS burst to measure.
A radio scanner is still your best, low cost bet.

Yeah right. Stick with audio Phil.
 
P

Phil Allison

Jan 1, 1970
0
"Anthony Fremont = Asinine **** "

It's not his fault you misunderstood him.


** It is entirly his fault for posting the wrong info.

The rest of us didn't have that problem.


** What an idiotic bloody lie.

You are wrong.


** Nope - it is true of the vast majority of counters.

The B&K 106 only needs a 250uS burst to measure.

** Cite ?

Yeah right.


** Thanks for the vote.

Now, go shove you pointy, totally fuckhead head back up you slimy arse.




......... Phil
 
A

Anthony Fremont

Jan 1, 1970
0
Phil said:
"Anthony Fremont = Asinine **** "




** It is entirly his fault for posting the wrong info.

NO, it's entirely your problem for jumping to the wrong conclusion and
thinking it's the OP's fault.
** What an idiotic bloody lie.

Well, most didn't.
** Nope - it is true of the vast majority of counters.

That isn't all of them. At any rate, it only has to last for a maximum of
two gate times on "the vast majority of counters".
** Cite ?

_I_ just gave you one. If you need a confirmation, look it up.
** Thanks for the vote.

I guess you cut the rest out and put it up on your bathroom mirror.
Now, go shove you pointy, totally fuckhead head back up you slimy
arse.

Can't you be more clever than that? If you don't like being treated like a
dick, stop acting like one.
 
P

Phil Allison

Jan 1, 1970
0
"Anthony Fremont = Asinine ASD Fucked **** "


** It is entirly his fault for posting the wrong info.

Well, most didn't.

** Another idiotic bloody lie.


That isn't all of them.


** Yawn - more asinine ASD fucked drivel.


_I_ just gave you one.


** Cite the info.

Can't you be more clever than that?


** Yes - go get your arse fucked by a dead donkey.

Enjoy.



....... Phil
 
P

Phil Allison

Jan 1, 1970
0
"Anthony Fremont = Asinine ASD Fucked **** "
In case you don't believe that, here's the datasheet:
http://www.bkprecision.com/www/np_pdf.asp?m=106


** Shame that is not the same counter you suggested earlier.

Shame if the pulses are shorter than 250uS.

The OP already has a radio scanner with no such limitation.


Piss off - you vile, autistic donkey fucker.




........ Phil
 
A

Anthony Fremont

Jan 1, 1970
0
Phil said:
"Anthony Fremont"


** Shame that is not the same counter you suggested earlier.

I never said it was. I suggested the cheap one first. I'm sure it will fit
his needs just fine. I referenced the other one just to set you straight.
Different problems, different tools.
Shame if the pulses are shorter than 250uS.

What kind of baud rate do you think they're using Phil? Maybe it's DSS?
The OP already has a radio scanner with no such limitation.

Fat lot of good that will do him with transmissions <250uS, huh?
Piss off - you vile, autistic donkey fucker.

Come back again when you need some more learnin'
 
E

ehsjr

Jan 1, 1970
0
Jim said:
Or use a spectrum analyzer and antenna.
Optoelectronics used to make low-cost receiver/counters for this sort of
thing;are they still in business?

Yes. AT the low end of their line, the "Cub" covers
1MHz - 2.8 GHz. On sale for $129. They have other
units, the "Cub" is the only one I'm familiar with.

http://www.optoelectronics.com/cub.htm

Ed
 
P

Phil Allison

Jan 1, 1970
0
"Anthony Fremont = Asinine ASD Fucked **** "

I never said it was. I suggested the cheap one first. I'm sure it will
fit his needs just fine. I referenced the other one just to set you
straight.


** I was never wrong.

Sampling frequency counters are rare items.


What kind of baud rate do you think they're using Phil? Maybe it's DSS?


** Shame if the UNINTERRUPTED RF pulses are all shorter than 250uS.

Fat lot of good that will do him with transmissions <250uS, huh?


** The repetition rate of data bursts is audible in the speaker.


Piss off - you vile, autistic donkey cock sucker.






........ Phil
 
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