[Ips-hf-warning] IPS HF SWF COMMS WARNING

[rwc]

SUBJ: IPS HF RADIO COMMUNICATIONS WARNING 07/48
ISSUED AT 31/0128Z DECEMBER 2007
BY THE AUSTRALIAN SPACE FORECAST CENTRE.

HF COMMS FADEOUTS EXPECTED DURING DAYLIGHT HOURS
FROM 31 DECEMBER 2007 TO 02 JANUARY 2008
IF COMMS DIFFICULTIES EXPERIENCED TRY A HIGHER FREQUENCY BAND
_____________________________________________________________

SOLAR ACTIVITY FORECAST       HF COMMS FADEOUTS             
31 Dec:  Low                  Possible
01 Jan:  Low                  Possible
02 Jan:  Low                  Possible


Note:
An IPS MUF depression HF Warning and IPS shortwave fadeout 
HF Warning are both current. Shortwave fadeouts degrade 
lower shortwave radio frequencies first (through increased 
ionospheric absorption) and the usual strategy during shortwave 
fadeouts is to try a higher frequency. In contrast, during 
periods of ionospheric MUF depression, the upper frequencies 
are degraded first and the usual strategy is to use a 
lower frequency. 

In general use a lower frequency if you are having trouble
with your normal workable frequency.

If a shortwave fadeout occurs during a period when ionospheric 
MUFs are depressed the available HF bandwidth will be "squeezed", 
with increased absorption raising the lowest usable frequency 
and the ionospheric depression lowering the highest usable 
frequency. Under such conditions it is suggested that the 
HF communicator operates on the highest usable frequency, 
even though this may well be in fact lower than what is normally 
supported for that particular circuit.

IPS Radio and Space Services        email: asfc at ips.gov.au
PO Box 1386                         WWW: http://www.ips.gov.au
Haymarket NSW 1240  AUSTRALIA       FTP: ftp://ftp.ips.gov.au 
tel: +61 2 9213 8010                fax: +61 2 9213 8060 

IMPORTANT: This e-mail, including any attachments, may contain,
confidential or copyright information.  The views expressed in 
this message are those of the individual sender, unless 
specifically stated to be the views of IPS.  If you are not 
the intended recipient, please contact the sender immediately 
and delete all copies of this e-mail and attachments. 
Occasionally IPS sends email promoting IPS products and 
services to its mailing list customers. If you do not wish to 
receive this promotional material please email 
no-spam at ips.gov.au with the subject header:UNSUBSCRIBE"