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Get the frequency of the signals around you

B

butthead

Jan 1, 1970
0
Hi,
I would like to build a device that would detect via an antenna a
certain range of frequencies (may it be RF, ultrasounds, sonar..) and
give the value.
 
K

Ken Taylor

Jan 1, 1970
0
butthead said:
Hi,
I would like to build a device that would detect via an antenna a
certain range of frequencies (may it be RF, ultrasounds, sonar..) and
give the value.

Look up 'spectrum analyzer'.

Ken
 
B

Ben Pope

Jan 1, 1970
0
butthead said:
Hi,
I would like to build a device that would detect via an antenna a
certain range of frequencies (may it be RF, ultrasounds, sonar..) and
give the value.

Well for a start you need to define your signal type.

RF is an electromagnetic signal.

Ultrasound and sonar or longitudinal pressure waves.

Two VERY different things.

An idea of the frequency range is useful too. For example most people can
pick up electromagnetic radiation of 430-750THz and classify that pretty
well with their eyes.

You'll need different techniques for different frequency ranges.

Ben
 
A

Active8

Jan 1, 1970
0
Hi,
I would like to build a device that would detect via an antenna a
certain range of frequencies (may it be RF, ultrasounds, sonar..) and
give the value.

have fun. you're looking at $100 or so just to build the front-end and
1st mixer using Mini-Circuits or MaComm parts. Optoelectronics used to
make a snooper that would do this for you, but it's classified as a
nearfield detector and they may have been forced to stop selling them to
the general public because it blows the cover of the cops and they can't
handle hand signals like soldiers.

mike
 
N

N. Thornton

Jan 1, 1970
0
Hi,
I would like to build a device that would detect via an antenna a
certain range of frequencies (may it be RF, ultrasounds, sonar..) and
give the value.

Hi. I have detected the signals around you. I can safely say 99% of
them are of no value at all. Some of the rest are of great value.

Regards, NT
 
B

butthead

Jan 1, 1970
0
Ben Pope said:
Well for a start you need to define your signal type.

RF is an electromagnetic signal.

Ultrasound and sonar or longitudinal pressure waves.

Two VERY different things.

An idea of the frequency range is useful too. For example most people can
pick up electromagnetic radiation of 430-750THz and classify that pretty
well with their eyes.

You'll need different techniques for different frequency ranges.

Ben

Hi,
I know that these waves are different but i don't mind the range. I
mean wether it is to pick up RF frequencies or to pick frequencies
emitted by a remote control...
I just wanna get an idea
 
B

Ben Pope

Jan 1, 1970
0
butthead said:
Hi,
I know that these waves are different but i don't mind the range. I
mean wether it is to pick up RF frequencies or to pick frequencies
emitted by a remote control...

Well they're both EM radiation, but obviously at significantly different
frequencies.
I just wanna get an idea


So you want to know specific frequencies in a narrow band or rough
frequencies in a very wide band?

You'd like a meter that says you currently have lots of RF on the FM band,
and somebody is pointing a remote control at you, and the micowave in the
kitchen is currently on. But nobody is using their mobile phone in the
vacinity.

That type of thing?

Ben
 
A

Active8

Jan 1, 1970
0
Hi. I have detected the signals around you. I can safely say 99% of
them are of no value at all. Some of the rest are of great value.

Regards, NT
but he said around *you*, not *him*. :)

i'm currently receiving signals around me but i'm not *get*ting them.

brs,
mike
 
K

Keith R. Williams

Jan 1, 1970
0
Hi,
I would like to build a device that would detect via an antenna a
certain range of frequencies (may it be RF, ultrasounds, sonar..) and
give the value.
Newsie? Is that you?
 
P

Paul Burridge

Jan 1, 1970
0
have fun. you're looking at $100 or so just to build the front-end and
1st mixer using Mini-Circuits or MaComm parts. Optoelectronics used to
make a snooper that would do this for you, but it's classified as a
nearfield detector and they may have been forced to stop selling them to
the general public because it blows the cover of the cops and they can't
handle hand signals like soldiers.

"Nearfield detector" eh? Sounds like a very useful piece of test
equipment for the radio amateur who likes to build his own stuff.
Check for out-of-band emissions, harmonic radiation and so forth. Are
they widely available outside of the US?
 
P

Paul Burridge

Jan 1, 1970
0
have fun. you're looking at $100 or so just to build the front-end and
1st mixer using Mini-Circuits or MaComm parts. Optoelectronics used to
make a snooper that would do this for you, but it's classified as a
nearfield detector and they may have been forced to stop selling them to
the general public because it blows the cover of the cops and they can't
handle hand signals like soldiers.

But surely this device is just a cheap 'n' chearful type of spectrum
analyser, isn't it? How can they ban the sale of SAs?
 
A

Active8

Jan 1, 1970
0
But surely this device is just a cheap 'n' chearful type of spectrum
analyser, isn't it? How can they ban the sale of SAs?
most likely.

the rumor(?) of the ban had do do with the fact that it's sort of a
surveillance device. if you lived in the woods, you wouldn't expect a
near field signal from say a cop car. since the cops are too lame to
observe radio silence... in the city, you would know what was normal and
a sudden near field emmision in the cop band would alert you.

i don't know if you can get one. goto the Optoelectronics website. i
forget what it was called. the description says it all. the BW is
enormous.

but i wouldn't use it as a lab tool for emmisions. it's not going to
tell you how many dB down your harmonics and spurs are. just filter your
bot controller real good and get a HAM to help check emmisions if you're
worried.

it does (did) log signal freqs received into memory and i think it had a
vibrate mode to alert you to a nearfield emmision.

mike

BTW. i got one of their $350, most excellent freq counters. it arrived
in a box emblazoned with "made in the USA" or "proudly made...". the
damn thing didn't work. impatient, i opened it and the solder on the
surface mounted hold switch looked suspect. a wiggle pulled the switch
off the board. immediate problem solved - they won't count on hold. poss
long term prob... bad QC.
 
M

maxfoo

Jan 1, 1970
0
Hi,
I would like to build a device that would detect via an antenna a
certain range of frequencies (may it be RF, ultrasounds, sonar..) and
give the value.

Do a google search for "grid dip meter".
 
P

Paul Burridge

Jan 1, 1970
0
Do a google search for "grid dip meter".

Most of 'em are deaf as a post. One assumes the OP wants a reasonable
amount of sensitivity.
 
M

maxfoo

Jan 1, 1970
0
Most of 'em are deaf as a post. One assumes the OP wants a reasonable
amount of sensitivity.

Do you know what they same about assume?
 
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