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PEAK & PEP
- Thread starter KJ4BAE
- Start date
Now there is also a difference between Peak power and True Peak Power. Peak power is always used to get accurate SSB power readings but......its not going to show (True) Peak Power unless the meter states it does.
Easiest way to tell a true Peak reading meter is they have to run on a power source for peak readings rather it be 9 volt battery of wall wart transformer I cant remember exactly what the rule is on measurement between peak and true peak I think it was a standard peak will give a certain percentage of the total peak and thats where True PEP comes in to give you a total reading.
Im thinking Standard PEP gave 30% of the total PEP which obviously wouldnt be a true PEP reading. please someone correct me if Im off with the 30%
Easiest way to tell a true Peak reading meter is they have to run on a power source for peak readings rather it be 9 volt battery of wall wart transformer I cant remember exactly what the rule is on measurement between peak and true peak I think it was a standard peak will give a certain percentage of the total peak and thats where True PEP comes in to give you a total reading.
Im thinking Standard PEP gave 30% of the total PEP which obviously wouldnt be a true PEP reading. please someone correct me if Im off with the 30%
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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.
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.
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.
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and dont forget guys that a meter is still an average way of seeing the watts. radio waves travel as fast as the speed of light 186,000 miles per second. as well as the energy traveling through the coax. to see real watts you have to use a scope and a spectrum analizer because the energy moves way to fast for any analog meter to understand what frequency is going into the meter. then you have to have a powered meter to really see good peaks. but really who the hell has the money for all that bull. lol 
I think you and I just read the same post. :headbang
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 was waiting to see what/how others answered this before sticking my two cents in it. Glad I did now! I have seen the correct answer stated in two ways. I have seen a couple of answers that are very interesting (I'm being nice). And a couple that while exactly correct, didn't exactly address the question, but were exactly correct. About the only thing I can think of that wasn't covered in some way was the 'Peak Hold' feature of some meters.
This is almost as much fun as spitting watermelon seeds... at customers in Wal-Mart.
- 'Doc
This is almost as much fun as spitting watermelon seeds... at customers in Wal-Mart.
- 'Doc
Here's where it gets real interesting and also confusing. The way that QRN described the definition of "peak" is also often called, "peak instantaneous power". However, most people that talk about "peak" output are simply abbreviating PEP in casual conversation. It gets even worse because amateur equipment manufacturers interchange Peak and PEP all the time on the labels of their equipment. You have to read the specs to see which one they really mean. Don't feel so bad about not understanding...if the mfg's were consistent with their usage it would help a lot.
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