tone decoder bandwidth

[freddy_uk]

hi,

im trying to build a tone decoder to detect any tone within 500hz to 3000hz, has anyone any idea weather i will need more than one tone decoder, i dont have a clue about the value of any of the components

please help if you can!!

 

[Mikebits]

One decoder will due. As I stated in your other post, the calculations are in the data sheet.

For center freq : use Fo= 1/1.1(R1C1)

Bw = 1070 √vin/FoC2

Vin will have an affect on BW so you must determine this value. You should be able to ball park it.

see data sheet for more info.

 

[blueroomelectronics]

Do they still make the LM567 tone decoder?

 

[freddy_uk]

Do they still make the LM567 tone decoder?

i fear you might be right, anyone got any ideas what i can use in its place need to detect tones all tones between 500hz to 3000hz

 

[mvs sarma]

i fear you might be right, anyone got any ideas what i can use in its place need to detect tones all tones between 500hz to 3000hz

See the datasheet for CD4046. it could serve you,perhaps

 

[KMoffett]

i fear you might be right, anyone got any ideas what i can use in its place need to detect tones all tones between 500hz to 3000hz

How accurate does it need to be? Is f=>500Hz and f=<3000Hz OK, but f=<499 and f=>3001Hz will be rejected? Would a simple bandpass filter be OK? What signal levels are you dealing with?

Ken

 

[freddy_uk]

there is an audio tone present on the cable, between 500 and 3000 hz, when i use my inductive amplifier (tone tester) i think im getting alot of interferance from <500hz, but i haven't got any test equipment so its hard to tell but it sound a low tone if you know what i mean.

my off the cuff research & testing so far consists of this...

i found this video on youtube YouTube - Hearing Test

it has tones on it, when i play these through my headphones, i use this inductive amplifier **broken link removed**

i can clearly hear the tones when i turn up the volume on the pc but in reality the tones are not that loud, i think about 20db, i need to amplify them some how and filter out the tones below 500hz

hope this explains abit more

 

[mvs sarma]

there is an audio tone present on the cable, between 500 and 3000 hz, when i use my inductive amplifier (tone tester) i think im getting alot of interferance from <500hz, but i haven't got any test equipment so its hard to tell but it sound a low tone if you know what i mean.

my off the cuff research & testing so far consists of this...

i found this video on youtube YouTube - Hearing Test

it has tones on it, when i play these through my headphones, i use this inductive amplifier **broken link removed**

i can clearly hear the tones when i turn up the volume on the pc but in reality the tones are not that loud, i think about 20db, i need to amplify them some how and filter out the tones below 500hz

hope this explains abit more

if the db level of the tone on the cable is so low that noise overtakes, perhaps PLL even may not do much. we must have a way to maintain signal to noise ratio (SNR)
May be the level at the sending end can be up by few db. or the cab;lle pair needs to be checked as to how the interference is coming from?
in applications like telecom, interference comes due to wrong paining of wires(un-pairing). Other wise in balanced working, signal levels upto near ly -38dbm can be handled.

 

[mvs sarma]

there is an audio tone present on the cable, between 500 and 3000 hz, when i use my inductive amplifier (tone tester) i think im getting alot of interferance from <500hz, but i haven't got any test equipment so its hard to tell but it sound a low tone if you know what i mean.

my off the cuff research & testing so far consists of this...

i found this video on youtube YouTube - Hearing Test

it has tones on it, when i play these through my headphones, i use this inductive amplifier **broken link removed**

i can clearly hear the tones when i turn up the volume on the pc but in reality the tones are not that loud, i think about 20db, i need to amplify them some how and filter out the tones below 500hz

hope this explains abit more

if the db level of the tone on the cable is so low that noise overtakes, perhaps PLL even may not do much. we must have a way to maintain signal to noise ratio (SNR)
May be the level at the sending end can be up by few db. or the cab;lle pair needs to be checked as to how the interference is coming from?
in applications like telecom, interference comes due to wrong paining of wires(un-pairing). Other wise in balanced working, signal levels upto near ly -38dbm can be handled.

 

[freddy_uk]

if the db level of the tone on the cable is so low that noise overtakes, perhaps PLL even may not do much. we must have a way to maintain signal to noise ratio (SNR)
May be the level at the sending end can be up by few db. or the cab;lle pair needs to be checked as to how the interference is coming from?
in applications like telecom, interference comes due to wrong paining of wires(un-pairing). Other wise in balanced working, signal levels upto near ly -38dbm can be handled.

thats dbm i know db but not seen dbm before

can you think of anything, its really important i come up with some ideas

thanks

 

[mvs sarma]

thats dbm i know db but not seen dbm before

can you think of anything, its really important i come up with some ideas

thanks

most important TERM used by communication engineers and that need not be explained on a site.

your text books deal it in more consolidated form.

 

[Mikebits]

thats dbm i know db but not seen dbm before

can you think of anything, its really important i come up with some ideas

thanks

dB is just a ratio and not referenced, so 0dB has no real meaning other than a relative number. dBm is with respect to 1 mw. So 0 dBm = 1 milliwatt. In RF the dBm is referenced to 1 mw into 50Ω, in audio it is 600Ω. A good rule of thumb to know is that a 3 dB increase is a double in the power so 0dB = 1mw, 3 dB = 2mw, 6dB = 4mw etc...