conversion of dc voltage to dbm meter as display

[subhash a nair]

Sir,
Can you help to make a project

the idea is to measure dc voltage in to dbm and the dbm level is to be displayed on a small lcd screen.

with regards.....

 

[Harald Kapp]

What is the question?

• How to measure dc voltage?
• How to convert voltage level to dBm?
• How to display the result?

Which components will you be using? E.g. A/D converter, microcontroller, display?
Whic accuracy do you need?

My basic setup would be:

• Analog front end (attenuator, gain stage, lowpass filter) as required in the application.
• microcontroller with built-in A/D converter (if accuracy is suffficient)
• LCD to display results (preferably with serial interface to connect it to the microcontroller with only a few pins.
• Software to digitize the analog data sing the built-in ADC, convert the measured voltage into dBm, then display it on the lCD.

 

[davenn]

Sir,
Can you help to make a project

the idea is to measure dc voltage in to dbm and the dbm level is to be displayed on a small lcd screen.

with regards.....

what is the signal source you are trying to measure ?
I assume you do realise that dBm is a measurement of power level ?
0dBm = 1 mW ( milli Watt)

 

[AnalogKid]

the idea is to measure dc voltage in to dbm and the dbm level is to be displayed on a small lcd screen.

That's a good idea.

ak

 

[Arouse1973]

dbm what? with out the other bit at the end i.e voltage or watts it's means nothing. Which would be dbmV or dbmW.
Adam

 

[davenn]

dbm what? with out the other bit at the end i.e voltage or watts it's means nothing. Which would be dbmV or dbmW.
Adam

NO .... dBm ALWAYS refers to W and in this case the reference is 1mW

dBV is for voltage and will be stated if its dBmV with reference to 1 mV

maybe the OP didn't know that

 

[Arouse1973]

Did he state watts?

 

[davenn]

Did he state watts?

NO, BUT he stated a Watts measurement unit
As I said I suspect he doesn't know the difference

IF he's wanting to stay in volts then it needs to be explicitly stated dBmV

dBm on it's own is for power

 

[CDRIVE]

If you're going to display voltage as dbm this voltage must be measured across a resistive load. 600Ω is the standard for audio while 50Ω is considered the standard for RF.

Chris