Dan Jacobson wrote:

I'm curious about two types of transmissions from aircrafts:
1. squawk transponder Mode-C Secondary Surveillance Radar (SSR) or whatever
2. ACARS

I know ACARS is around 131 Mkz usually, but what frequency is the SSR stuff?

What would they sound like on a scanner? Does ACARS sound indeed like
a short bird squawk, listening in AM mode? I will attempt to decode it
with acarsd.org's Linux program.

How about VOR's, ~110-115 Mhz, listening in AM mode? My squelch opens
up but all I hear is silence, correct?

What does TACAN sound like?

Describe them, don't just refer me to some sound files that are too
big for little me to download.

P.S. CW means Morse code, but what about the CWP seen on aviation
maps' frequency tables, does it just mean the same?


SSR uses two frequencies for all modes (A, C, S, 1, 2, 3, 4, etc.) they
are 1030 and 1090 MHz, I can't remember which is interrogator and which
is transponder - it's late and I'm not inclined to look it up right now.
If you hear a short burst of digital pulses at regular intervals -
typically 5 to 10 seconds - it is an interrogator. If there is a mixture
of signals of varying strength at random intervals you are listening to
the transponders.

VOR, if you are in a quiet environment and listen carefully, has a slow
very low frequency variation - but they have a CW identifier and some
have voice broadcasts of weather information.

TACAN is also up in the 1,000 MHz range and I have no recollection of
what it sounds like - listening to digital signals has never seemed
particularly productive to me.

I'm curious about the CWP since it is not familiar to me and I don't
recall seeing it in my Flight Supplement, or maps and charts - maybe it
is one of those things one sees so often it doesn't get noticed but I
can't even find it in the Flight Supplement list of abbreviations and
acronyms. By the way cw in my Flight Supplement decodes as clockwise!

Dave