Control Channel on 858.8625

[n3bxv]

I'm picking up what sounds like a Control Channel on 858.8625, however I cant' get it to decode with Trunker or my Pro-96. Any Ideas?

 

[troymail]

I'm in your area and not picking anything up on that freq....

 

[n3bxv]

Hmmm, perhaps I have an problem, I'm also getting a control channel on 859.9125 that won't decode.. An Image or some sort of intermod? I'm hearing it on a 895xlt, 898t and my pro-96.... I'm about a mile from the Jessup tower for AACO, so it might be originating from there and overloading or otherwise causing the problem...

Thanks for checking.

 

[TinEar]

Chuck, I'm hearing both those control channels. The one on 859 is super strong.
And neither is decoding.

Alan

 

[n3bxv]

Ok, so I'm not going crazy.... Perhaps part of the new MdTA BWI system? Interesting.

Hmmm... According to the FCC both of these Frequencies are licensed to AERONAUTICAL RADIO INC (ARINC) of Annapolis and used at multiple airports around the country within trunked systems managed by them..

Added - Yeah I know there are a bunch of other licensees, but I thought the connection to ARINC and Annapolis was interesting.

 

[ka3jjz]

If indeed this is ARINC, I have heard several rumors - maybe now confirmed - that the ARINC ground users - such as USAir and Southwest, who used to use a very small 800 mhz type 1 system at BWI - were moving to a network of some kind (I want to say Iden but that's not right...). Anyway that might account for the fact that Trunker can't handle it.

I know ARINC has made several such conversions at other airports - I wonder why it took so long for BWI - which is quite literally only a hop skip and a jump away from the Riva Road Annapolis headquarters - to get on board? Anyway, that seems like a likely conclusion. 73s Mike

 

[troymail]

OK - I am getting 859.9125 - but it's kinda weak - fades in and out... I think I'm closer to the airport than you are... can't hear the 858 and the 859 is weak...

edit - ok -- I moved around my house and I can now hear the 858 but it's extremely weak.

 

[n3bxv]

The other possiblity is that it's a system temporarily set up by ARINC in Annapolis for testing or ??

Mike, here's the system I think you were thinking of - AviNet Wireless Dispatch.. ARINC's implementation of IDEN...
http://www.arinc.com/products/voice_data_comm/avinet/wireless_dispatch.html

 

[TinEar]

Mike, iDEN is a system used by ARINC. From their website....

ARINC voice and data communication solutions also allow mobile ground crews separated at airports across the country to keep in constant touch. ARINC's AviNet Wireless Dispatch Service gives these personnel a highly reliable, multifunctional voice/data "cell phone" that uses Motorola's advanced Integrated Digital Enhanced Network (iDEN) technology and leverages ARINC's nationwide communications network. This single device takes the place of a phone, pager, and radio, and supports text as well as voice. This means that controllers, aircrews, and ground-support personnel can communicate conveniently and accurately without being drowned out or cut off by other communications traffic.

 

[Llwellyn]

Wow, I'm picking these up loud and clear up in my neck of the woods! It's a different digital burst than I'm used to, it doesn't sound like any trunked channel that I've heard used in the area before. I'm trying to pin it down by finding clips of trunked channels to compare the audio. It's 9600 baud or faster, leaning towards 9600 baud. It's way faster than a 3600 baud moto CC, and it almost sounds like it could be even faster compared to a 9600 baud moto CC.

Does FedEx have a license for those freqs by any chance? Here's a likely suspect:
CDPD - Cellular Digital Packet Data - Typically uses vacant cellular voice channels to transmit 19200 baud data. FedEx apparently uses a dedicated frequency system in Chicago on 860.8625 and other freqs. http://www.kb9ukd.com/digital/cdpd.wav

Also, could be... either this system or a new OpenSky type system here...
M/A-Com - OpenSky Data Network - See CDPD, above Apparently uses private CDPD for data. Voice is a 2 slot TDMA AMBE CODEC from DVSI and likely sounds different from this. 851-869 MHz band Pennsylvania state system

It's definitely not EDACS of any flavor, or Nextel/Moto iDEN. http://www.kb9ukd.com/digital/mot_iden.wav

It's interesting, because both of the channels have a very similar modulation pattern but their audio frequency is slightly shifted (by a little less than 1 semitone).

EDIT: FedEx is licensed for both of those frequencies here in Maryland in both Baltimore and Frederick. The 859.9125 frequency is licensed to 4 locations with output power of up to 125 watts. Their license is for conventional radio though.

 

[troymail]

This must prove I'm in a hole since I can barely hear them but folks near the Jessup tower and in Brooklyn Park hear them fine....

I agree - the sound is quite different from those I'm used to hearing... it almost sounds like two signals on top of each other -- sounds like a control channel with a faint sound of of another digital signal (something very fast) layered on top of it

 

[doctordave]

I'm actually getting the 858 freq booming at 5/5 in Northern Balt Co.....the 859 freq is a bit weak up here.