<html>
<body>
<font color="#000080">At 12:31 06-09-10, Phil wrote:<br><br>
</font><blockquote type=cite class=cite cite="">***** High Performance
Software Defined Radio Discussion List *****<br>
<font face="Arial, Helvetica">...</font><br>
<font face="Arial, Helvetica">Is a VHF/UHF receiver with an overload at
this level usable in
Europe?</font></blockquote><font color="#000080"><br>
Another back-of -envelope calculation. I have a dear friend that has
4x17el and 1kW, and he lives 40 km from my QTH (in line of sight).<br>
The ERP is in the order of 200 kW, and the field at my QTH is -24.6 dBm
on an isotropic antenna. With my 17 dBi antenna and -1 dB cable I get
-8.6 dBm at the RX input.<br>
This is, unfortunately, quite a common situation in EU... when we point
each other there is no way, the mutual interference is assured,
expecially because of TX noise sidebands and RX reciprocal mixing. The
required blocking dynamic range, assuming an SSB channel and 2 dB NF,
should be 130 dB (-137 to -7 dBm), and the same for the transmitter!<br>
Of course, all we know that analogic receivers have a gradual
degradation, and we are used to it. I presume that contest users will not
be very happy with a suddenly saturating ADC.<br>
I will test it, however. I'm setting up a fixed station, where the
antenna feeder (after an LNA) splits via a 3 dB splitter. One branch goes
to an IC-910H (with all due switchings to allow transmission), the other
goes to an high dynamic converter and then to a Perseus. I hope to
get some practical results (and figures) in next few
months.<br><br>
73 - Marco IK1ODO<br><br>
</font></body>
</html>