[Milsurplus] Signal Corps Info Golden Nuggets.

[Hue Miller]

----- Original Message -----
From: David Stinson <arc5@ix.netcom.com>

> I recently purchased a large stack of Signal Corps documents from
WWII....

> I'm posting this excerpt because of an old argument about
> whether airborne radio equipment was ever used to broadcast
> on the AM band:

> OFFICER'S SCHOOL
> RADIO SECTION

> ...Reports recently received by the War Department clearly indicate
> that the enemy is quite likely to disrupt our radio communication
> by jamming.  Jamming signals may be keyed continuous wave (CW),
> modulated continuous wave (MCW), voice, music, imitation static,
> phony broadcasts or other types of noise.
> The jamming equipment may be located on the ground
> or installed in aircraft...
> ...the main purposes of the enemy in jamming (are) to cause panic
> and disorganization in our forces through impairment or disruption
> of radio communication and by spreading propaganda and rumors....

> While this does not directly say that broadcasting took
> place from aircraft, it is a tantalizing piece of
> a very tough puzzle.

> 73 Dave S. AB5S

-Dave, is there really a question of whether aircraft transmitted
(NOT
broadcast - that is a separate question) on the MW broadcast band
frequencies?
My previous posts on this mentioned 2 incidents from  WW2 Pacific
War, where US planes having made a discovery, in one account, of
an enemy ship force, and the  second, of the Indianapolis survivors -
and the planes then sent homing signals for other US aircraft to
follow to the location. The standard DF receivers for US Navy
aircraft did not  offer DF above 1500 kHz. So what frequencies were
being used by the aircraft that was sending the homing signals?

As for actual "broadcasts" from planes - this AFAIK is a Cold War
innovation. For one thing, to get any respectable range, you need
power in the kW range, not 50-100 watts. If you have to use a
transmitter in the power class of the BC-375, #1 you have to get
close enuff to your target that you would be a sitting duck for AA
in the 90mm class. Also, you would be making the erroneous
unrealistic assumption that a lot of  "pirate broadcaster" hobbyists
still make: that there's lots of people just tuning around, looking
for
your new and unique broadcasts - which isn't the way broadcasting
works for the mass audience.
Now re jamming of  broadcasts: this takes mass power, and single
jamming of one station is futile.

It seems to me the case is closed on why aircraft had transmit
capability on LF and MF  ( or using the terms LW and MW - anyway,
meaning 200 - 1500 kHz. )

BTW, this just occurred to me also - didn't the German FuG10 set
transmitter for LF - the S10L- didn't that transmitter have some kind
of pulse modulation, so that the aircraft's LF signal could be used
by ground station to get a bearing on the  aircraft?

Wasn't there also a procedure, called something like "QTD", that
had an aircraft call a land station to get a bearing, get DF
information
from the aircraft's signal? This was surely on LF or MF....
(sorry about my vagueness on this.....)

Another use for these transmitters came to me, altho i doubt whether
they were envisioned for use on the ground. ( But at least the BC-191
could have been envisioned for such a use....) This would be for LF
beacon stations on small forward airfields, in  combat zones - such
as
some of the small island fields in the Pacific area....
50-100 W would be sufficient for such stations....in fact the power
levels
of beacons in the 200-400 kHz range in the USA today, is on that
level
of power, something like 20-250 watts, is it not?
I don't subscribe to command set list- someone feel  free to copy
this there.
Hue Miller