Hello Markus,
Well, so, i just got 19 uV/m and the distance is 178.2 km. So this
should be 25.57 + 45 + 3.6 - 49.5 = 24.7 dBm, i.e. 540 mW ERP :-(
I see what must be improved...
73, Stefan
Am 03.08.2011 13:03, schrieb Markus Vester:
Hi Stefan, LF,
there is no peak-hold function, so your carrier has to be
present at the grabber capture time. Allowing for a bit of clock
uncertainty, you would want to transmit for say 20 seconds around any
five minute multiple.
Here's an example for ERP calculation:
E = 20 uV/m at R = 200 km distance would give
EMRP = 26 + 46 + 4 - 49.5 = 26.5 dBm = 450 mW
Dipole ERP = 0.82 W
To calculate the distance R to my receiver you could use
Best regards,
Markus (DF6NM)
-----Ursprüngliche
Mitteilung-----
Von: Stefan Schäfer <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Di., 2. Aug. 2011, 23:46
Betreff: Re: LF: Fieldstrength and radiated power
Thanks
Markus,
Will try now if it works and see what my level will be ;-) Good for PA
adjustments, at least in times without a skywave component. Anyway...
So, do we have to send a longer dash or acidentally transmit to the
right time? :-)
73, Stefan/DK7FC
Am 02.08.2011 18:26, schrieb Markus Vester:
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)
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