728kbi t/ sec Coder, and modulate a 6. SS2MHz carrier signal
using the quadrature-phase-shift-keying (QPSK) modulation
system, with differential data encoding. The serial data
source can be an external coder or, for test purposes, an
internal pseudo-random binary sequence or fixed 16-bit
data-pattern generator. It is possible to select between
the QPSK or VSB-2PSK modulation systems, and to apply
amplitude-frequency pre-correction. All phase modulation
and transmit data-shaping filtering is implemented
available, to give a final carrier-frequency at IF or UHF.
Power requirements 240Vac. PN3/S4. Sub-units PS4/44,
C09/S04G, C02/29, C02/30, GE4/21, MD4S/7, GE2/19. RD 1987.
Modulator. This unit forms the core of the Digital Stereo
Sound with Terrestrial Television Modulator. This all-
digital modulator synthesises a 2.912 MHz carrier signal,
which is phase-shift-key modulated according to the
incoming 728 kbit/sec data. The modulated carrier signal
is output as 8-bit digital data, ready for digital-to-
analogue conversion to reconstruct the analogue 2.912 MHz
carrier waveform. The modulator is capable of generating
many different PSK modulation systems, with or without
offsets, and/or absolute or differential coding of the
data. The characteristics of the modulation system and all
data shaping filtering are uniquely determined by data held
in PROMs. Power requirements +S V, !12 V. 4U unsupported
PCB with PN1/29J front panel. Parent equipment MD4SM/6.
Chassis extender CH4/S. RD 1987.
2048kbit/sec TFM Modulator. This unit accepts two
quadrature baseband inputs from the CD2/40, and modulates
the data onto a 7.SMHz carrier. It is intended for use
with CD2/40, DM4/10 and CD3/S6. Power requirements !SV.
CH1/86K. Parent equipment TM2L/7. Supersedes MD4/S.
D & ED (RF) 1987.
MODEM 3.3kHz Data Unit. This unit is a modem that is used
for two way data transmission on Inter-Region 48kHz Group
Links. It has a fixed carrier frequency of 3.3kHz that is
modulated at a rate of I baud. The demodu lator will
reproduce the I baud data rate and provide TTL outputs and
local LED indications. Power requirements -20V at SOmA.
1 card 114mm x 312mm. Parent equipment Post Office. DD
1979. DDMI 6.383(80).
Long Distance Modem. Unit containing a commercial Modem.
"Gandalf LDS 120", RS232 to RS422 interface and power
supply for data communication over a 4 wire circuit of 2400
bauds ,distances up to 8 kilometres. Power requirements
240V AC. CH1/64C chassis. Parent equipment PA1M/126. DD
Measuring Unit. Accepts inputs from MN1/S13, selects and
standardises for presenting to Measure Control Unit. Part
of system display I.T.S. parameters on Monitoring and
Information Centre V .D. U. Power requirements !12V d .c.
CH1/64J. DD 1979.