Dear LF,
to support estimates of radiated power, I have added a
fieldstrength readout on my LF grabber
It simply displays the peak frequency and amplitude within the
QRSS subband at the time of the capture (ie. every five minutes). Due
to different calibration issues, the readout will be accurate only to
within about 3 dB. There may also be considerable day-to-day variation,
for example from switching between different receive antennas.
In the region of groundwave dominance (up to 400 km daytime, 200
km in darkness), radiated power in dBm or milliwatts can be roughly
estimated based on distance R using
EMRP[dBm] = 20 log E[uV/m] + 20 log R[km] + 0.02 R[km] - 49.5
EMRP[mW] = 10^(EMRP[dBm]/10)
To convert to halfwave-dipole ERP or EIRP, you would have to
apply the usual factor of 1.83 or 3.
Hope this may be useful...
Best 73,
Markus (DF6NM)
