PEAK & PEP  | | 
10-14-2009, 12:33 PM
|  | Senior Member | | Join Date: May 2007 Location: tustin, ca
Posts: 381
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Quote:
Originally Posted by unit_399  The RMS value is equal to the peak value times 0.707. | That is true only for a sine wave.
Voice is not a sine wave, and voice is not symmetrical. 3 ways of expressing voltage of a common AC wave form
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10-14-2009, 12:56 PM
|  | Honkus Maximus | | Join Date: Dec 2008 Location: My Signal Covers Dixie Like The Dew
Posts: 697
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Quote:
Originally Posted by unit_399 Viewing a pure symmetrical sine wave (with no dc bias) on an oscilloscope, the total vertical displacement (maximum positive TO maximum negative) is the PEAK to PEAK voltage. In the same symmetrical waveform, the maximum positive OR maximum negative excursion is called the PEAK voltage, and it is one half of the peak to peak reading. The RMS value is equal to the peak value times 0.707. For example, home electricity is 117V rms, 165.5v peak , and 331v peak to peak.
- 399 |
That's some fine brainiakin' boys 
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10-14-2009, 01:24 PM
|  | Senior Member | | Join Date: Aug 2005
Posts: 1,937
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Quote:
Originally Posted by Beetle PEAK power can only be determined for waveforms that are relatively constant, such as power lines at 60 Hz. With purely sinusoidal, constant level waveforms, the math is a snap - and you can easily measure it with a calibrated oscilloscope.
PEAK ENVELOPE POWER (PEP) is a little more complex, since it involves the waveform as modulated by a human voice or by a multitone audio signal. RF wattmeters typically measure average (not RMS) power. There are some meters that have a "PEAK" position on their switches, but these are NOT reliable in that switch position.
Meters that will accurately read PEP must have active circuitry to analyze the RF waveform, do the math, and display it on the instrument's face. In order for the instrument to do that, it needs to have either an internal battery, or an external power source, to provide the power for that active circuitry.
Some MFJ meters (and others, I suspect) have wallwarts available that will power the lights for the meter face. Check the specifications carefully and ignore switch position markings. You're the buyer, so beware. | I think it is possible to measure peak power of any kind of RF energy, constant or not... |
10-14-2009, 01:35 PM
| | Senior Member | | Join Date: Aug 2005
Posts: 1,937
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Quote:
Originally Posted by QRN I think you and I just read the same post.  
I guess the easiest and most basic way to define it is that peak power is the peak or greatest power output that is delivered to a load at any time during operation. Peak envelope power is the average power supplied to the antenna transmission line by a transmitter during one radio frequency cycle at the crest of the modulation envelope, under normal operating conditions of an amplitude modulated waveform. Peak is relativley easy to measure. Pep is not quite so easy. | I'm confused...
While I agree that peak power is the peak or greatest power output that is delivered to a load at any time during operation.
Wouldn't this value be just as difficult to determine as PEP? |
10-14-2009, 03:25 PM
|  | Bigstrapper | | Join Date: Jun 2008 Location: REPUBLIC de COLOMBIA
Posts: 203
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QRM's definition is correct. For a quantitative explanation of Peak vs Peak-to-Peak check this link. www.cbtricks.com/members/kd6tas/amsig.htm |
10-14-2009, 04:54 PM
|  | Senior Member | | Join Date: Dec 2005 Location: Western Washington
Posts: 1,225
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Who's "QRM"?
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10-14-2009, 07:16 PM
|  | Prestigious Member | | Join Date: Feb 2008 Location: too close to mexico
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Quote:
Originally Posted by Beetle Who's "QRM"? | This thread is full of it who ever it is.
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10-14-2009, 07:18 PM
| | Bigstrapper | | Join Date: Jun 2008 Location: REPUBLIC de COLOMBIA
Posts: 203
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Quote:
Originally Posted by Beetle Who's "QRM"? |
I meant QRN... sorry.
QRM ??? I don't know him either. Some day I will learn how to type.
- 399 |
10-14-2009, 08:32 PM
|  | Senior Member | | Join Date: Apr 2005 Location: Wisconsin
Posts: 3,032
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I think thberes 2 QRM's I hear them everynight on 80 meters when the group I belong to tries to talk. 
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