Utdrag ur ”Beskrivning över
5-kanalutrustning” Juni 1953
GENERAL DESCRIPTION
The G.E.C. Five Circuit
Carrier Equipment provides 5 300-2800c/s speech circuits together with
signalling facilities and is designed for operation over radio links.
The five circuits are
transmitted to, and received from, the radio equipment as one audio
circuit plus four carrier circuits. The carrier circuits employ single
sideband suppressed carrier system of transmission.
Two carrier frequencies
are employed for modulating the circuits,·one 6.667kc/s serves circuits
2 and 3 while the other 13.333kc/s serves circuits 4 and 5. Both of
these frequencies are derived from a common 100kc/s crystal controlled
master oscillator. The total frequency band transmitted to and received
from the radio equipment is 0.3 to 16.133kc/s. The following table shows
the frequency band of each circuit.
CIRCUIT |
FREQUENCY BAND |
No.1 Unmodulated |
0.3 to 2.8kc/s. |
No.2 Lower
sideband of modulation with 6.667kc/s. |
3.867 to
6.367kc/s. |
No.3 Upper
sideband of modulation with 6.667kc/s. |
6.967 to
9.467kc/s. |
No.4 Lower
sideband of modulation with 13.333kc/s. |
10.533 to
13.033kc/s. |
No.5 Upper
sideband of modulation with 13.333kc/ s. |
13.633 to
16.133kc/s. |
The speech circuits may·be
extended on either a 2-wire or a 4-wire basis. Selection of either
method is by the movement of the two multi-way plugs.
The equipment is
continuously adjustable to cover a speech channel input range of -10 to
0dbm (-14 to +4dbm for 4-wire extensions). Continuous adjustment is also
provided to cover a speech channel output range of -10 to 0dbm (-6 to
+14dbm for 4 wire extensions).
The sideband level
transmitted to the radio transmitter is -26dbm (per channel) and the
sideband level (per channel) received from the radio receiver is 0dbm.
A 2280c/s tone is used to
give voice frequency signalling facilities over the circuits. Convertors
are provided at each end of the circuit to convert the 2280c/s tone to
17c/s ringing and vice versa. The convertors may also be used for DC
signalling, if this is required.
The equipment is built up
of eight panels mounted in a folded steel framework. The panels slide
into guides fitted on the inside edges of the rack. Covers are provided
for each panel and these are secured by self-locking fasteners.
Electrical connexions between the rack wiring and the panels are made by
means of multi-way plug-in links fitted between sockets, one set being
mounted at each end of the panel, and the other sets on the panel
guides.
All external connexions
other than the power supply are made to terminal strips mounted at the
top of the rack.
Sammanställt av Roland Persson
Senast uppdaterad 2014-03-11
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Utdrag ur ”Beskrivning över
5-kanalutrustning” Juni 1953
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