TRANSMITTER RESERVE FEED
SYSTEM OVERVIEW
EQUIPMENT
Equipment is provided for both the transmitter site and at the studio site.
At the transmitter site the equipment is housed in two 1U subracks. These are coded
GS1U-030 and GS1U-031. The GS1U-030 contains most of the electronics while the GS1U-031
contains basically just the relays that perform the actual switching.
At the studio site the equipment is housed in a single 1U subrack code GS1U-032. Some
studios may feed several transmitter sites. The GS1U-032 can be equipped to feed up to six
different transmitters with, if necessary, six different programmes.
The design for both the studio and transmitter equipment is based on our GSGC9 ISDN
Module. This is a Eurocard size unit that contains a dual terminal adapter and two codecs
each of which can automatically use the G722 ("data" for music line) or the G711
("voice" for telephone) algorithms. It is controlled by using DTMF (i.e. the
"touch tones" generated by all modern phones) and provides information to the
user with recorded messages.
(We have substantially re engineered this module for use at the transmitter site. It is
now built on a larger PCB that fits directly into the 1U subrack and has many hardware and
software changes)
At the studio end , the standard GSGC9 is used with only minor hardware modifications
(e.g. omission of the break jacks) and with no software modifications.
OPERATION IF MAIN TRANSMITTER FEED FAILS
The GS1U-030 continuously monitors the main transmitter feeds. If programme level
on either stereo leg is lower than a defined level for longer than a defined period, the
unit will dial up the studio and feed the transmitter with the reserve mono feed*. A
number of safeguards are built into this procedure.
(* unless automatic reserve has been manually disabled)
EMERGENCY OPERATION
It is possible to force the GS1U-030 to dial a particular studio and to replace the
main transmitter feed (whether failed or not) with an alternative mono feed. This
operation is performed using a normal DTMF telephone. For security reasons there are
several levels of safeguards built into this operation including CLI and PIN number
protection. The user is warned that "Automatic Reserve will be disabled", when
attempting manual control. Having made a manual control action the system will remain as
commanded until a further command places it back into Automatic mode.
SETTING UP THE SYSTEM
For initial set-ups on installation an RS232 port is provided on the front panel of
the GS1U-030 to interface with a PC. Most parameters, CLI and PIN numbers can then be set.
So that it is not necessary to visit the transmitter site in order to change parameters,
provision has been made to permit nearly all of them to be changed by calling the unit
using a standard DTMF telephone. Again security safeguards are provided.
Drawings (as .pdf files) are available for:
Links to Other ISDN Pages
GSGC5 GSGC6 GSGC8 GSGC9 GSGC17 GSGC25 GS3U-057 TX RESERVE