Hearing Uplinks: Why Not ?

[BOBRR]

Hello:

New at this, and was wondering a bit about the following.

i have tried some of the airline company frequencies that folks were good enough to provide.
A lot of them work, and can hear from the plane to ground just fine.

But never from the ground to the plane.

As this is AM, I thought I should be able to pick up both ways ?

As I believe these are via an ARINC facility, whey can't i hear the AM uplink ?

Is it that it is directed vertically (only) upwards in a very narrow cone ?

I can certainly hear the Boston Logan tower without any problem, so
thought these should be listenable to also ? Why not ?

Thanks,
bob

 

[wa8vzq]

Bob,

No the signal is not aimed straight up. As you know, you can hear the aircraft several hundred miles out. You typically need to be within 10 miles of the ground station to hear it. The ARINC transmitter sites are not necessarily located at an airport, at least here in MN they use some off-airport sites. Also, the FAA sites usually use a radio tower that is typically 40 feet tall. The other airport tenants such as ARINC typically mount their antennas on the roof of their buildings or hangars rather than using a tower so they will not have the same line of sight distance as the FAA equipment.

You might try checking this website:
http://svartifoss2.fcc.gov/reports/index.cfm

Check out the report Frequency (range) State.
Enter the frequency limits as M128.825 and M132.000

This should help you located ground stations near you plus help you to establish a frequency list. Keep in mind that the same frequency is used at multiple airports.

Regards

Dan
Apple valley, MN