die@frog.UUCP (Dave Emery) (11/06/84)
Recently some further information on current Air Force One
communications has been passed to me. It appears that only some
of the previously open circuits have been secured. Specifically :
1. The uhf-nbfm single channel duplex system code
named "nationwide" is still in use from AT&T microwave towers with traffic
in the clear on 415.700 mhz. from AF-1 and 407.850 mhz. from the ground.
2. The vhf-nbfm single channel duplex system code named "Yankee-Zulu" is
still in use from portable ground sites set up at presidential destinations.
It has been reported that it seems to be used for mostly for traffic from the
aircraft and may be in only limited use as a channel to reach presidential
automobiles. Recent reports suggest that this channel is being used for
traffic out to the limits of the ground site coverage rather than just until
the aircraft is in line of sight to a 'nationwide' ground site. Traffic is
in the clear on 171.2875 mhz from AF-1 and 162.6875 mhz from the ground.
3. The hf ssb circuits ("Mystic Star") continue to be used occasionally
for phone patch traffic to the aircraft, and are still in the clear.
However, propagation being what it is these days, transmitting traffic over
hf (both clear voice and secure tty) hasn't always been easy.
4. The nbfm full duplex circuit over the Fltsatcom spacecraft continues
to be used, with 260.845 and 260.860 used for downlinks to AF-1 and the
ground station at Andrews repectively. Data is occasionally exchanged
(secure voice or fax ?) but most of the time the circuit carries a holding
tone. One report says this circuit is used for occasional clear voice com
coordination traffic also.
5. Many of the secret service channels are still used in the clear.
I am told that presidential protective traffic in the clear has been observed
on secret service channels "Oscar" - 164.8875, "Sierra" - 166.5125,
"November" - 167.025, "Tango" 164.650, and the national channel "Charlie"-
165.375. One observer noted keyed carriers on "Mike" 165.2125 that may or may
not be some form of digital voice (not however classical DVP with an
audible preamble pattern), but as spectrum signature equipment was not
available it wasn't possible to certainly identify the nature of this signal.
Another observer reported what may be amplitude compandered ssb in use
on "Baker" 165.787 (I think this may just be an image from 2 meter ssb).
6. Recent tv coverage of the presidential vehicles in a motorcade
showed the same old high band vhf whips as the secret service has
always used, which would tend to confirm (5) or at least suggest that
no new rf frequencies have been assigned in some other portion of the
--
----
David I. Emery
Charles River Data Systems
983 Concord St.
Framingham, MA 01701
Tel: (617) 626-1102
uucp: ...!decvax!frog!diedie@frog.UUCP (Dave Emery) (11/06/84)
<line eater meat>
Recently some further information on current Air Force One
communications has been passed to me. It appears that only some
of the previously open circuits have been secured. Specifically :
1. The uhf-nbfm single channel duplex system code
named "nationwide" is still in use from AT&T microwave towers with traffic
in the clear on 415.700 mhz. from AF-1 and 407.850 mhz. from the ground.
2. The vhf-nbfm single channel duplex system code named "Yankee-Zulu" is
still in use from portable ground sites set up at presidential destinations.
It has been reported that it seems to be used for mostly for traffic from the
aircraft and may be in only limited use as a channel to reach presidential
automobiles. Recent reports suggest that this channel is being used for
traffic out to the limits of the ground site coverage rather than just until
the aircraft is in line of sight to a 'nationwide' ground site. Traffic is
in the clear on 171.2875 mhz from AF-1 and 162.6875 mhz from the ground.
3. The hf ssb circuits ("Mystic Star") continue to be used occasionally
for phone patch traffic to the aircraft, and are still in the clear.
However, propagation being what it is these days, transmitting traffic over
hf (both clear voice and secure tty) hasn't always been easy.
4. The nbfm full duplex circuit over the Fltsatcom spacecraft continues
to be used, with 260.845 and 260.860 used for downlinks to AF-1 and the
ground station at Andrews repectively. Data is occasionally exchanged
(secure voice or fax ?) but most of the time the circuit carries a holding
tone. One report says this circuit is used for occasional clear voice com
coordination traffic also.
5. The Autovon uhf-fdm mux signals seem no longer to be used, at least
in areas far from ground stations. I have received no reports of traffic
on these channels, and would appreciate hearing from anyone who can
verify that these links are no longer used. I would especially
appreciate hearing from someone who knows (and can say) what has
replaced these links.
6. Many of the secret service channels are still used in the clear.
I am told that presidential protective traffic in the clear has been observed
on secret service channels "Oscar" - 164.8875, "Sierra" - 166.5125,
"November" - 167.025, "Tango" 164.650, and the national channel "Charlie"-
165.375. One observer noted keyed carriers on "Mike" 165.2125 that may or may
not be some form of digital voice (not however classical DVP with an
audible preamble pattern), but as spectrum signature equipment was not
available it wasn't possible to certainly identify the nature of this signal.
Another observer reported what may be amplitude compandered ssb in use
on "Baker" 165.787 (I think this may just be an image from 2 meter ssb).
7. Recent tv coverage of the presidential vehicles in a motorcade
showed the same old high band vhf whips that the secret service has
always used, which would tend to confirm (6) or at least suggest that
no new rf frequencies have been assigned in some other portion of the
spectrum.
--
----
David I. Emery
Charles River Data Systems
983 Concord St.
Framingham, MA 01701
Tel: (617) 626-1102
uucp: ...!decvax!frog!die