GB3TM OVERHAUL & UPGRADE
B3TM on the North Coast of Anglesey has recently been undergoing
maintenance and minor upgrades .
Transmitter 1316MHz QPSK
AGAF DATV Encoder and Modulator board settings have been changed to
provide improved picture resolution. New settings:
Elementary Stream 6MB/s
Symbol Rate 4.167 MS/s
Video-PID 33 (decimal)
Audio-PID 49 (decimal)
A 2-metre receiver on 144.750 MHz has been installed and the audio
output from this is taken to the B audio channel input on the Digital
Transmitter to provide talk-back.
Analogue Transmitter 1316MHz FM
The Analogue Transmitter has been in continuous operation for 16 years,
since July 1994 and had been suffering some minor problems. These have
now been corrected and the various transmission parameters checked and
readjusted as necessary. After checks and maintenance, the Analogue
Transmitting Aerial has been moved back from its temporary location to
its original (higher) position which should resume normal coverage.
output can be switched between Analogue and Digital with DTMF tones on
the incoming 6MHz FM audio channel. The default mode is Digital.
Present DTMF codes are:
DTMF 1 Digital transmission
2 Analogue transmission 15
3 Test Card
on 1 minute
4 Test Card off
Receive 1249MHz FM
is now powered from a UPS to prevent problems caused by intermittent
brown-outs of the mains supply. The possibility of an additional Digital
Receive facility is under review.
Photograph of the GB3TM Technical Team at the Site: (Photo GW4KAZ)
Brian GW4KAZ, John GW3JGA and Repeater Keeper David GW8PBX
Submitted by GW3JGA and GW8PBX 18.10.2010
Update October 2011.