Modes Questions

[BOBRR]

Hello,

I understand that commercial air is generally AM, but was wondering about the following:

Is the ATIS system at airports AM or FM ?

How about Unicom ?

Any other(s) freq's for commercial air comms that are perhaps FM ?
-----------
And a general question re MIL air:

Are these generally AM or FM ?

Thanks,
Bob

 

[ecps92]

Civilian A/C operations 108-137 Mhz are all AM
Radio Scanner Guide - Part 3C: Civilian Aircraft

Hello,

I understand that commercial air is generally AM, but was wondering about the following:

Is the ATIS system at airports AM or FM ?

How about Unicom ?

Any other(s) freq's for commercial air comms that are perhaps FM ?
-----------
And a general question re MIL air:

Are these generally AM or FM ?

Thanks,
Bob

 

[CalebATC]

ecps92 is correct, in the 108-137 band, everything is AM. Every aviation realted thing at an airport will be AM.

I do most of my monitoring on military bands, so I do have the second answer:
The 138.XXX-140.XXX are MOSTLY AM, but you will find that some of them are FM. Most of what I hear is AM, but I do get alot of FM from Customs And Border Patrol helicopters down here in Florida.

In the UHF Band (2XX-3XX), I guarantee everything will be AM, except possibly a MILSAT.

Although when scanning for planes, I reccomend you use AM. 95% of the time it will be AM.

Let me know if you need any help!

Hope this helps!
Caleb

 

[BOBRR]

From OP Re Modes Question

Hi all,

Just a quick thanks for info. on the Modes.

I'm about 20 miles due West of Logan.
Can usually pick up incoming planes O.K., but almost never anything from Logan itself.

Perhaps the emissions from Logan are pointed more or less straight upwards; sort of like a cone with the point at the Tower antennas ?

Will have to research for a better antenna, probably.

Have one radio hooked up to a disconne, and the other to a Scantenna.ST.

Regards,
Bob

 

[ka3jjz]

<snip>
In the UHF Band (2XX-3XX), I guarantee everything will be AM, except possibly a MILSAT.
</snip>
Caleb

Not quite; in the 380-399 mhz area, many military and federal installations are moving to this area and setting up P25 trunk systems. Fortunately this is quite easy to recognize. Some systems are encrypted, others are not. However there are still many 'holes' in this region where air comms (still AM) can be heard - not all freqs are used everywhere

73 Mike

 

[ka3jjz]

Hi all,

Just a quick thanks for info. on the Modes.

I'm about 20 miles due West of Logan.
Can usually pick up incoming planes O.K., but almost never anything from Logan itself.

Perhaps the emissions from Logan are pointed more or less straight upwards; sort of like a cone with the point at the Tower antennas ?

Will have to research for a better antenna, probably.

Have one radio hooked up to a disconne, and the other to a Scantenna.ST.

Regards,
Bob

That's more or less right Bob. You would likely need a beam of some sort at 20 miles to hear Logan tower and ground ops. Oh and by the way, it's discone (no 2 n's) :wink:

73 Mike

 

[joefitz232]

Yes, you will need a beam to receive comms from the surface at Logan if you are to the west. There are some hills and tall buildings that weaken and scatter most of the signals. Try to avoid preamps and stick with good antennas and cables, and things should work out alright.

 

[CalebATC]

Yes, you will need a beam to receive comms from the surface at Logan if you are to the west. There are some hills and tall buildings that weaken and scatter most of the signals. Try to avoid preamps and stick with good antennas and cables, and things should work out alright.

Definately avoid preamps near Boston!

 

[DaveNF2G]

I would not use a preamp for anything below about 1 GHz.