Please provide details of "your" dynamic cone penetrometer.  As you will note in many other threads, there is a large variation in the type of equipment used; hence, in the correlations, etc.  In Canadian practice we drive a 2 inch (51mm) cone with 60deg apex angle attached to A-rods with 140 lb. hammer dropping 30 inches (convert to SI if you must!!).  The Canadian foundation engineering manual has correlations with standard "N" values - then you can use normally accepted correlations (with judgment).
For other pentrometers - the TRRL miniature one or the "Sowers"?? one, you will have differences.  Check out other threads by a search as this has been discussed in detail previously.

The DCP in question is the one with 10Kg mass falling through 460mm height onto 60 degree angled cone of diameter 20mm.

Please check it out .

Thank you

check out threads:

thread261-59796
thread274-48778

I posted my take once before, gone now.  But the helical pile industry has to base a depth estimate on something, and sometimes blow count and soil type is all you get.  So you establish formulas to relate C, phi, and gamma to the blow count. It just gets you close.  In the Piedmonts I still only get 80% accuracy.  I've got phi nailed though.

Sowers' Book (2nd or 3rd edition) give this correlation.

It's best to create your own correlation with a DCP and SPT right next to each other.  I've found that published correlations vary considerably depending on geology.