|
|
 |
|
|
|
|
Helpful Guidance For Downlinking CDC Programs
|
Successful downlinking of satellite programs requires careful
attention to the satellite specifications provided by CDC and experience using the local
site's receiver equipment. Best results will occur if sites use a knowledgeable technician
to program and steer the satellite dish. If that is not possible for each program, the
personnel designated to downlink programs should learn as much as they can about their
equipment from the technician who programs it and follow the guidance below.
Background
CDC cannot control which satellites are used for a particular program. CDC has set
standards for the purchase of all satellite time, e.g., full transponder capability and
both C- and Ku-Band access. However, there are no guarantees that we will get what we
request. Project personnel purchase satellite time from the open market a minimum of 30
days prior to the broadcast date. Availability of satellite space at the time the
procurement is processed determines which satellites are used. Sometimes it is very
difficult to find 2 different satellites on different bands with 3 continuous hours of
available time, which is why coordinates are sometimes late in being released.
Satellite Guidance
Accessing a Satellite Program.
In order to tune into a CDC satellite program,
you must have 1) a steerable antenna capable of receiving either C- or Ku-Band satellite
transmissions and 2) the satellite coordinates designated for the particular program you
are trying to access. CDC normally posts the coordinates on the PHTN website at http://www.phppo.cdc.gov/phtn within 30 days of the broadcast
date. The coordinates specify which satellites on the C- and KU-Bands are being used. You
will need to program your receiver with the code that matches either of these satellites,
depending on your band capability.
Programming the Analog Receiver.
Most sites have satellite receivers that can be
pre-programmed to access the various satellites in the arc over North America. It is
critical that the programming of the receiver be done correctly and accurately. We
recommend that this be done by a qualified local technician, competent with both C- and
Ku-Bands, at the time of installation and updated annually.
Program Codes.
The codes which the technician programs into your system are not standardized
system-wide. They may vary from state to state or even from technician to technician. For
example, the satellite Telstar 4 may be coded as "T4" in one receiver and
"T1" in another. The specific codes used are not as critical as the fact that
the technician tracks each code created and lists it in writing on a chart for you next to
the satellite name. This should be done for each and every main satellite in the North
American arc. The chart attached displays the most widely used satellites in North
America, as well as a typical code for each. Note that the letter/number combinations can
only be used once in programming a satellite. The far left hand column has been left blank
for you to record your receiver's programmed codes. We recommend that you/your technician
complete the entire chart, showing the codes for each satellite. Then date and post it
near your equipment, so that anyone who needs this information about your system can
easily access it.
Receiver
Operator. Once your receiver is fully and accurately programmed, it is
recommended that a particular person be designated to operate the machine at all times. An
additional person should be identified and trained as a back-up. It is also recommended
that the operator prepare a detailed, step-by-step "how-to operate the receiver"
guide for any time that the main designee is not available.
Pre-Program
Test. As soon as you obtain the coordinates for a program, immediately
verify that your receiver is programmed for the satellite(s) specified. Then, utilize the
test time designated (normally the day prior to the broadcast) to check the signal. Do not
wait until the actual broadcast to perform this check.
Annual Code and Satellite Check.
The satellite business is a dynamic one. New satellites are launched and old ones inactivated all the time. For
that reason, it is critical that you have your list of codes and equipment checked by a
reputable technician once a year at a minimum. This updating process will help to ensure
that your receiver is accessing the right satellites for your programs.
Dual
C- and Ku-Band Capabilities.
Some satellites are low-powered and provide weak signals. Therefore, it would be beneficial for
each downlink site to have capability to receive both C- and Ku-Bands. If both bands are
accessible and properly programmed, switching from one to the other will provide you the
versatility to select the stronger of the two signals, thus providing clearer reception.
If you currently do not have both C- and Ku-Band capability, ask your technician what the
cost would be to upgrade your system. This should not require a new dish, only hardware.
The advantage of having the option to switch to a stronger, clearer satellite band when a
signal is coming in weak will generally outweigh the cost associated with the upgrade.
Points of Contact.
The guidance noted above will hopefully help you to access our satellite programs more easily, but may
not resolve every single issue you have. In the event you have further need for guidance,
please use these contacts:
In regard to downlinking a particular CDC program - Technical Trouble Line
at (800) 728-8232.
If the satellites are accurately programmed and you still are having trouble downlinking a
particular program, you should call our technical trouble line. This number is only
accessible during the one hour satellite coordinate test the day prior to the program and
during the program itself.
In regard to your satellite equipment - If you have other questions regarding your
satellite equipment, we recommend that you check with a reputable local technician to
ensure your equipment is working and accurately programmed.
In regard to PHTN Distance Learning events mailto:phtnweb@cdc.gov
Satellite Transponder Guide |
This page last reviewed: February 20, 2004
|
|
