UHF mil air

[mike445]

TACAMO flight burning mux on 338.950MHz 2030Z 14JAN19

SENTRY 06 (E-3B 964th AACS/ 552nd ACW Tinker AFB, OK) setting up air to air refuel with GETTY(?) 21 (GETTY DC CAP tanker) on 343.25 2145Z

06 tells 21 we're completing our first orbit, do you need more time?

I hear the TACAMO flights often here in SW Arkansas on 338.950 and 383.550. I’ve also caught some strange data bursts on 351.000. Pretty interesting stuff.
Mike

[Josh]

Hi Mike, nice to have another ear aboard. Didn't have 351 in the rx, will see if anything pops up.

[mike445]

Hi Mike, nice to have another ear aboard. Didn't have 351 in the rx, will see if anything pops up.

351.000 was different. Very strange. At first I thought it was interference so I tested it on three other scanners and SDR and all different antennas for each. I could post a short video of it here if I was able to.

I hear TACAMO right now on 301.650 AM. Why are the data streams in NFM some days and AM others?
Mike C.

[mike445]

Hi Mike, nice to have another ear aboard. Didn't have 351 in the rx, will see if anything pops up.

Good to be part of the forum.  I posted a clip to my FLIKR.  Here is the link for 351.000:
https://flic.kr/p/2ig4N8x

Quite a bit different than TACAMO.  The same data stream (I'm assuming) popped up on 351.350 and 234.950 as well.  It would alternate between those 3 frequencies.

Here is a link for 351.350:
https://flic.kr/p/2ig1BNg

There was a B52 from Barksdale nearby (heard him on 311.000) and an E3 Sentry.
Mike

[Josh]

I'd have to have a i/q of the entire sig to run it thru the batputer. Top o' me head says this was from the Sentry, with the BUFF you mention a close second.

As to the tacamo wideband mux, it's always wideband fm, 60kc wide I think, with various amplitude modulated sigs superimposed on the channelised mux stream. There will be two mux flowing, uplink and downlink, I'm not in range of any uplink that I know of, haven't heard any. There has been mention of a digital version to replace the analog wideband fm link but have yet to see it here. Somewhere around the start of this thread are some video links to steps taken by a monitor to extract specific channels from the mux, so you might take a look at them if you haven't.

[ChrisSmolinski]

One of these days I am finally going to hear some UHF mil air traffic... 

[mike445]

I'd have to have a i/q of the entire sig to run it thru the batputer. Top o' me head says this was from the Sentry, with the BUFF you mention a close second.

As to the tacamo wideband mux, it's always wideband fm, 60kc wide I think, with various amplitude modulated sigs superimposed on the channelised mux stream. There will be two mux flowing, uplink and downlink, I'm not in range of any uplink that I know of, haven't heard any. There has been mention of a digital version to replace the analog wideband fm link but have yet to see it here. Somewhere around the start of this thread are some video links to steps taken by a monitor to extract specific channels from the mux, so you might take a look at them if you haven't.

Thank you. I’ll go start from page one and go through the posts. I hear them burning here all the time. Sometimes USB voice. Very interesting stuff. Thanks for ask your insight.
Mike

[Josh]

The why for this specific frequency range and choice of modulation methodology is due to one overwhelming  criterion; nuclear explosions.

When a nuke pops, it ionises a large region surrounding the fireball to the extent radio comms thru the fireball/mushroom cloud are completely absorbed. From around mw thru hf to lower vhf, radio comms will be down or degraded for several hours after the pop. Testing (popping real nukes) showed that high vhf to uhf sigs were least affected by nukes going off, so the planes and ground stations tasked with comms during national emergencies were devised with the v/uhf mux system, with high power and efficient antennae. Fm mode was chosen due its inherent amplitude/noise rejection properties as well as longstanding means to multiplex fm.

Speaking of mux, someone just fired up on 366.600 @ 1949Z 23JAN19 lol

[R4002]

One of these days I am finally going to hear some UHF mil air traffic... 

With your discone it shouldn't be too much of a problem. 

Also: any VHF low band/mid band FM mil air traffic and VHF AM mil air (including the 137-144 MHz and 148-150.775 MHz band).  142.125 MHz AM, 49.725 MHz FM and several others are in use in my area by the Virginia Air National Guard - I know there's heavy UHF air band activity the closer you get to Norfolk, etc. 

I feel like you should be able to hear the D.C. area comms, at least some of them from higher-altitude aircraft. 

[Josh]

I'm sure the smolinksi kid was being condescending.

[NJQA]

I hear mil-air stuff.  I am sure there is a lot of traffic Chris can hear.

The 225-400 band is big and it is easy to miss stuff.  Maybe start with some power surveys to identify good target frequencies?  Try this:

http://kmkeen.com/rtl-power/

[ChrisSmolinski]

I'm sure the smolinksi kid was being condescending.

No, honestly, I have tried a few times but never heard anything. I think the problem is the air band is huge and I have no idea where to look.

[Josh]

Yeah not like there's 34 pages of frequencies and links to freqs right here or anything.

[Josh]

I hear mil-air stuff.  I am sure there is a lot of traffic Chris can hear.

The 225-400 band is big and it is easy to miss stuff.  Maybe start with some power surveys to identify good target frequencies?  Try this:

http://kmkeen.com/rtl-power/

The saving grace of the rtl is it has a autotuning v/uhf bandpass filter that comes into play on those bands. It can be narrowed to 30 or mebbe it was 300kc. Not all apps for the rtl mention this filter but it's built in the hardware, dunno if the hardware does it automagically or if the app must expose the functionality and the user select it.

HDSDR is my fav app for rtl by the way, your cpu won't even notice the app is running.

[ChrisSmolinski]

Yeah not like there's 34 pages of frequencies and links to freqs right here or anything.

How location specific are the frequencies? It's not like it's HF where you have a chance of hearing it no matter your QTH