Program Mod to support Airspy "Bias T"

[tjkaminski]

I love modesdeco2 -- I am using an Odroid XU4 with the Airspy unit and a 1090 preamp/bandpass filter.  I constructed a 7-segment CoCo antenna form RG402 and it is tuned spot on (SWR 1.5 at exactly 1090).  With the antenna top at 12 feet  and shaded by trees and houses, I am receiving planes out to 170 nm.  I am sure range will improve when I mount it higher.

Problem:  I want to feed the preamp up the coax from the AIrspy Bias T option.  Airspy's toolset supports it, but it is turned off when I run modesdeco2.  Please consider adding an option to set the "bias T" enable when starting the Airspy unit. The specific Airspy option is:

     [-b biast]: Set Bias Tee, 1=enabled, 0=disabled(default) 

[sergsero]

Hello tjkaminski,

Sorry for the late reply. I will try to add support for this option as soon as get back from vacation.

Regards,
sergsero

[tjkaminski]

Thanks, it will be appreciated.  Have fun on you vacation.

[sergsero]

Hello,

New version of modesdeco2 with option --airspy-rfbias (The Bias-Tee option: 4.5v @ 50mA) was tested. In the near future I will try to upload it.

sergsero@ac168:~/sdr/modesdeco/build/modesdeco$ ./modesdeco --airspy --verbose --airspy-rfbias
2015-10-03 20:30:28.850  INFO     ModeSDeco2 v.20151003
2015-10-03 20:30:28.852  INFO     Board ID Number: 0 (AIRSPY)
2015-10-03 20:30:28.852  INFO     Firmware Version: AirSpy NOS v1.0.0-rc4-0-g23d1436 2015-03-22
2015-10-03 20:30:28.852  INFO     Part ID Number: 0x6906002B 0x00000030
2015-10-03 20:30:28.852  INFO     Serial Number: 0x16C463C82
2015-10-03 20:30:28.853  INFO     Supported sample rates: 10.0 2.5
2015-10-03 20:30:28.853  INFO     Oversampling Factor: 5
2015-10-03 20:30:28.853  INFO     RF Bias: On
2015-10-03 20:30:28.853  INFO     LNA Gain: 15
2015-10-03 20:30:28.854  INFO     Mixer Gain: 15
2015-10-03 20:30:28.854  INFO     IF Gain: 8

The Bias-Tee option allows powering such a preamplifier directly from Airspy by injecting DC at 4.5v. Of course, such a preamp should have its own biasing system to extract the DC and inject the amplified RF signals. The current budget is limited to 50mA, so that's enough to run most of the modern MMICs.

Regards,
sergsero

[sergsero]

The version 20151005 for test new option --airspy-rfbias for Airspy receiver.

+ added Bias-Tee option --airspy-rfbias that allows powering a LNA directly from Airspy by injecting DC at 4.5v.
   A preamplifier should have its own biasing system to extract the DC and inject the amplified RF signals. The current budget of Airspy is limited to 50mA.

  Please note!
  If you have used the option --airspy-rfbias, the supply voltage on the sma connector will be remain until you disconnect the receiver from the USB port or to re-run the program without this option. 


Windows
modesdeco2_windows_20151005.zip https://drive.google.com/open?id=0B7NYXizl0U6iOWNNajU4VkNfZDA

Ubuntu 14.04
modesdeco2_i386_20151005.tgz https://drive.google.com/open?id=0B7NYXizl0U6iLVdBU1ZpamxxY0k
modesdeco2_x86_64_20151005.tgz https://drive.google.com/open?id=0B7NYXizl0U6iekJ6WFZwb0lVVTg


If you are connected the Airspy in Ubuntu for the first time, it is possible that you need to add some udev rules to make the receiver available for the non-root users: http://xdeco.org/?p=216

Regards,
sergsero