Information on the
change of recommended CTCSS repeater access tone
The
following was in the Wireless Institute of Australia news bulletin on the
2nd August 09.
Change of Tone!
Because 123
Hz was prone to interference such as music on the channel, FTAC has decided to
revise such & has now set 91.5 Hz as the general use tone for repeaters.
The WIA Band Plan has
been Updated to reflect this and other changes, the new Band plans are dated
July 24 2009.
The band
plan was updated to read-
The following CTCSS tones have been adopted for
repeater access:
91.5 Hz: For use with repeaters fitted with
CTCSS for interference protection.
141.3 or 146.2 Hz: To activate links to
repeaters on other VHF/UHF bands.
85.4 Hz: To activate links to other bands that
some operators are not permitted to use.
The
previously recommended 123 Hz tone has been withdrawn due to problems with false
detecting.
There is
much rumour and misunderstanding regarding this change. Some people think the change of
tone is mandatory. This is not correct. These CTCSS tones are
recommended and are not mandatory.
The WIA has no authority to insist any repeaters use any specific subtones. The
frequency chosen is entirely up to the individual repeater owners.
Here is
Gary VK2ZKT with further information-
As some
of you may have heard in the amateur media recently and perhaps discussed on air
there has been talk about changing the CTCSS access tone for repeaters to a
frequency below 100Hz.
Background
Some months ago a meeting was convened in Sydney by
a number of repeater operators of metropolitan repeaters and representatives
from the WIA technical repeater Committee. The purpose of this meeting was to
discuss issues relating to interference and linking issues,
especially in large metro areas. Country
areas are not the major problem.
A number
of Sydney based repeaters suffer various forms of interference including
:-
- Receiver
Blocking
- Intermod
products
- Cross
Modulation
- Intermittent opening of receivers by mixed products
containing CTCSS
- FM
Station desense
- and the
list goes on.....
In Sydney
especially a number of repeater sites are linked to networks that stretch over
large distances and are located at high density RF sites.
Information
Gathered
I
have contacted the WIA National Office in Melbourne and inquired as to
the outcome and possible moves in the area of CTCSS tone access
frequencies.
Mr Peter
Young VK3MV is the person overseeing this complex issue.
I spoke
at length to Diane Ashton in the office and Diane has informed me that no
decision has been made as to any if any change to CTCSS frequencies is to be
implemented at this stage.
Given the
many technical issues revolving around repeater interference a definitive
solution is not as simple as it sounds. Interference is a very much site by site
issue and the solutions will vary to suit that particular site problem
encountered.
Diane
indicated that she will follow up with Peter in the coming days and will provide
a reply as to the current status of these and other issues.
I will
let you know as soon as I know.
Regards,
Gary Ryan
VK2ZKT