[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

AO-40 lids

Ed Al7EB wrote:

Why some stations persist in running too close to the MB level is hard to
say (maybe they can't hear well, maybe they don't care, maybe it hasn't
been sufficiently explained to them).

Wayne W9AE replies:

I think the major reason is TREES and INTERFERENCE.  Based on what I hear on AO40, it is very common for at least ONE station in a 2-way QSO to be pointing through a tree and/or getting significant interference from a cordless phone.  My location has many trees, but cordless phones are far enough away that my noise blanker reduces the interference to "barely audible".  My last portable operation was at a location where the noise blanker was only able to reduce the cordless phone pulses to the level of the AO40 beacon.  Setting the receiver AGC to "fast" helped a little bit, but raised the noise floor.

Big dishes have enough gain to hear through some trees.  But big dishes are usually mounted close to the ground where tree and building obstruction is much worse than a rooftop or tower location.

For many of us, the best solution is a V or U downlink.  I look forward to the V downlink on P3E.  Trees won't affect me, and I won't have perpetual interference from cordless phones.  V and S downlinks are very complementary because they have "opposite" advantages and disadvantages.  V-band requires a long antenna, but the antenna has a small wind load, the radio equipment is simple, and there is no tree attenuation.  S-band allows a "small" antenna, but has large wind loading, significant tree attenuation, and significant interference from unlicensed devices.  Each person has a different value attached to each of these characteristics.  People with big trees and no tower usually prefer a V or U downlink.  Apartment dwellers usually prefer microwaves.  But the recent proliferation of unlicensed devices has made S-band an undesirable downlink for almost everybody.

Wayne Estes W9AE
Mundelein, IL, USA
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org