Hi both, I had no luck with rtl_airband so I’m interested to see how @abcd567 gets on.
If I wanted to listen to Airband I thought this might work:-
a simple spider antenna tuned to approx middle of the air band frequencies and use SDR# on a laptop and TCP connection to the RPi which runs rtl_tcp -a {IP of RPi}
Not that I would ever do that! 
I am by no means an expert, but will try to assist. This is a part of my config file:
devices:
(
{
type = “rtlsdr”;
index = 1;
gain = 28.0;
centerfreq = 127.275;
correction = 1;
sample_rate = 2.048;
channels:
(
{
freq = 126.475;
outputs:
(
{
type = “icecast”;
server = “127.0.0.1”;
port = 8787;
mountpoint = “atis.mp3”;
#name = “Hyderabad ATIS”;
username = “source”;
password = “XXXX”;
}
);
},
{
freq = 128.1;
outputs:
(
{
type = “icecast”;
server = “127.0.0.1”;
port = 8787;
mountpoint = “maa.mp3”;
#name = “Chennai Control”;
username = “source”;
password = “XXXX”;
},
{
type = “file”;
directory = “/home/ubuntu/audio”;
filename_template = “MAA”;
}
);
}
);
}
);
The formatting (braces and all) is what creates the confusion. This file, monitors two frequencies off one RTL dongle. The ATIS is not recorded, only streamed to an icecast output. The other one, is both streamed through icecast, and recorded on disk.
Idea is, you can have any number of frequencies monitored off a dongle, and they can have any number of outputs each.
I would suggest, start with one channel(frequency) and one dongle, and only choose the disk recording part. Run the program for a couple of minutes, stop it, transfer the recorded file through SSH etc., and then maybe add icecast/other frequencies.
BTW, I use the program as a systemd service. Here is my service file:
[Unit]
Description=RTL_Airband
After=network.target
Wants=network.target[Service]
ExecStart=/usr/local/bin/rtl_airband -Fe
Type=simple
Restart=on-failure
RestartSec=5[Install]
WantedBy=multi-user.target
Once started, it gives an output like this with systemctl audio status
Jul 27 23:16:08 ubuntu systemd[1]: Started RTL_Airband.
Jul 27 23:16:08 ubuntu rtl_airband[37317]: RTLSDR-Airband version v3.1.0-19-gc5ea8fb starting
Jul 27 23:16:09 ubuntu rtl_airband[37317]: Connecting to 127.0.0.1:8787/atis.mp3…
Jul 27 23:16:09 ubuntu rtl_airband[37317]: Connected to 127.0.0.1:8787/atis.mp3
Jul 27 23:16:09 ubuntu rtl_airband[37317]: Found Rafael Micro R820T tuner
Jul 27 23:16:10 ubuntu rtl_airband[37317]: [R82XX] PLL not locked!
Jul 27 23:16:10 ubuntu rtl_airband[37317]: Connecting to 127.0.0.1:8787/maa.mp3…
Jul 27 23:16:10 ubuntu rtl_airband[37317]: Connected to 127.0.0.1:8787/maa.mp3
Jul 27 23:16:10 ubuntu rtl_airband[37317]: Device #1: gain set to 28.00 dB
Jul 27 23:16:10 ubuntu rtl_airband[37317]: RTLSDR device 1 initialized
Please feel free to ask if anything confuses you. I have been using this for almost 4 years, and have disks full of recordings. Nifty little program 
You are the Champion. We are lucky to have you here. 
Tried with pi3 @abcd567 in Feb 2019
Setting up and running scanner no problems.
Had issues though with the following :
1, monitoring audio from pi on windows pc (client) on same network as pi (server)using icecast and vlc player
2. setting up scanner as said is okay but pulse audio on same pi3 and monitor audio (using pi as both client and server) connecting pi with laptop running real vnc/tight vnc
http://www.merseyradar.co.uk/airband-radio/new-sdr-radio-purchase-airspy-r2/
Great work!
I remember seeing your site sometimes ago when you sent me the link while you were working on L-band antenna/Jaero
I searched the Australian legislation and this appears to be the current act
To save you reading this real page turner the significant sections are
9 Definitions of device, non standard device and non standard transmitter
(1) For the purposes of this Act, a device is:
(a) a radiocommunications transmitter; or
(b) any other transmitter; or
(c) a radiocommunications receiver; or
(d) any other thing any use or function of which is capable of being interfered with by radio emission.
47 Unlawful possession of radiocommunications devices
(1) Subject to section 49, a person must not have a radiocommunications device in his or her possession for the purpose of operating the device otherwise than as authorised by:
(a) a spectrum licence; or
(b) an apparatus licence; or
(c) a class licence.
Penalty:
(a) if the radiocommunications device is a radiocommunications transmitter:
(i) if the offender is an individual—imprisonment for 2 years; or
(ii) otherwise—1,500 penalty units; or
(b) if the radiocommunications device is not a radiocommunications transmitter—20 penalty units.
(2) Subsection (1) does not apply if the person has a reasonable excuse.
Note: A defendant bears an evidential burden in relation to the matter in subsection (2) (see subsection 13.3(3) of the Criminal Code).
48 Additional provisions about possession of radiocommunications devices
(1) Without limiting section 47, a person is taken, for the purposes of that section, to have a radiocommunications device in his or her possession for the purpose of operation if it is in his or her possession, otherwise than for the purpose of supply to another person, and can be operated merely by doing one or more of the following:
(a) connecting the device to an electric power supply by means of an electric plug or other electrical connection;
(b) connecting a microphone to the device by inserting a microphone plug into the device;
(c) switching on the device;
(d) switching on any other equipment relevant to the device’s operation;
(e) adjusting settings by manipulating the device’s external switches, dials or other controls;
(f) connecting the device to an antenna.
(2) Subsection (1) only applies in the absence of any evidence to the contrary.
(3) A reference in this Division to a person having a radiocommunications device in his or her possession includes a reference to the person having it under control in any place whatever, whether for the use or benefit of that person or another person, and although another person has the actual possession or custody of it.
As the generic and non-filtered dongles cover TV reception it is not an offence to possess them.
It appears the filtered receivers are not permitted without authority.
Section 47 says
1) Subject to section 49, a person must not have a radiocommunications device in his or her possession for the purpose of operating the device otherwise than as authorised by:
Since we don’t have authorization for either 1090MHz nor ATC it seems it is an offence.
On the other hand, if you are authorized there doesn’t seem to be any restriction on streaming LiveATC.
However in the Wireless Telegraphy Act 1905 it states
Penalty for breach of Act.
6.—(1.) Except as authorized by or under this Act, no person shall—
(a) establish, erect, maintain, or use any station or appliance for the purpose of transmitting or receiving messages by means of wireless telegraphy; or
(b) transmit or receive messages by wireless telegraphy.
Penalty: Five hundred pounds, or imprisonment with or without hard labour for a term not exceeding Five years.
and also
### WIRELESS TELEGRAPHY REGULATIONS - SECT. 36.
Provisions as to secrecy
(3) A person shall not, without lawful authority, divulge, or make any use
whatsoever of, any portion of the text of any message transmitted or received
by any station whether situated in Australia or elsewhere, or disclose in any
manner whatsoever the existence of any such message.
but this has been repealed.
Should be some cheap used analog scanners available via ebay, kajiji, etc. Think every scanner has the AM air band for monitoring. I have an old radio shack scanner listening to the local channel(s) 24/7 so I know who’s up and about. I have 121.5 in the priority channel as well. I’ve never bothered with an outside antenna.
-Just if you want to listen for yourself… Easy to port audio to a sound-card tho…
Since last 10 years, I am using Grundig Satellit 750 receiver (not a scanner) to listen to Airband. No outdoor antenna, only by extending it’s telescopic antenna.
Prior to purchasing it, for over a decade I used a low cost common portable AM/FM receiver, whose FM tuner I had modified to receive Air Band. In additiin to modifying the FM tuner, I had to slightly detune it to get AM demodulation from FM demodulator by operating it at slope of FM demodulator curve. Hacked Airband
Here is a reasonable description of how FM slope detection and demodulation works.
Thanks @SweetPea11 for diagram & link. This is what I had found when I was trying to hack FM to Air band. Slight detuning was easy as I did not use a radio with digital (PLL) tuner. It was old fashioned analog receiver with variable gang capacitor, knob, needle & dial.
I took advantage of image frequency. When needle was set at 100 Mhz on the dial, the oscillator frequency was 100+IF= 100+10.7=110.7 mhz. This oscillator frequency not only hetrodyned with 100 mhz to produce IF (10.7 mhz), but also hetrodyned with 121.4 mhz to produce 10.7 mhz IF (121.4 - 110.7 = 10.7). Thus at dial reading of 100mhz (fm band), it could receive 121.4 mhz also (air band). However antenna coil+gang capacitor were designed to tune at 100 mhz when oscillator was at 110.4, so 121.4 was rejected. I simply changed antenna coil with lower inductance to tune antenna circuit at 121.4 mhz when dial was indicating 100 mhz and oscillator was at 110.7 mhz.
To summerize, the only thing I did to convert FM band to Air band was to replace antenna circuit coil with another coil of lesser number of turns (lesser inductanc).
Now the antenna circuit, which was tuning to (oscillator frequency - IF), started tuning to (oscillator frequency + IF)
How to choose manual squelch value? How does rtl_airband squelch value compare with SDRSharp squelch ?
In Spain, it is not legal either, only personal listening, never retransmission, I use SIRIO antenna for air band, much better than a radarbox antenna 
Does anyone have the Radarbox VHF airband antenna? I’m looking to improve my VHF airband long range reception and wonder if that antenna is really a good performer with its 5dbi gain. Otherwise I can build a dipole tuned to 127MHz for example…
Thank you
I haven’t tried personally but i know at least one person who was disappointed.
Why not make a three legged quarter wave?
Dipole is good as well but the commercial solution are often with radials, probably to suppress signals from below it.
Thanks for the quick reply.
Indeed I’m now looking at it…How To Build A 2 Meter Vertical Antenna – Mike's Tech Blog
A quarter wave ground plane as high as you can get it outdoors won’t disappoint, and is a competent reference for later experimentation. I’m running a $50 copper pipe J-pole through 15 feet of RG8-X and can clearly receive aircraft beyond 200 mi. in the location-favored azimuth. I chose the 'pole to get 1/2 wave of vertical metal in the air.
Thanks for your feedback. A quarter wave ground plane will be the one I’ll look for. I have a 20ft pvc mast to attach the antenna so that probably will be good enough for at least 200mi…
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