Observation: Airspy Mini and HackRF One under my local RFI and non-RFI conditions

[Ayushman Tripathi]

Test environment: SDRangel and VIRGO running on Ubuntu.

I was testing my local setup, observing near Capella (see attached Stellarium screenshot). I noticed that when my monitor is on, the H-line becomes very difficult to distinguish with the Airspy Mini in SDRangel, while it remains more clearly visible with the HackRF One. I have observed this several times over the last month.

I’ve also observed that if the RFI increases beyond this level, I stop getting usable results from the Airspy Mini and then even the RFI is not visible in the spectrum, at that point the spectrum becomes flat and then develops wavy small lines (I'll try to post the images of that soon) but the HackRF still gives the result.

Both SDRs were tested in SDRangel with same pointing and max gain settings. With the monitor off (reduced RFI), both perform similarly.

Attached:

• Today's SDRangel screenshots from both SDRs, with and without RFI

• VIRGO plot from HackRF with RFI, captured at the same time and pointing

I'll run longer observations and then compare again. Tried various Airspy Mini settings but couldn't improve results in the high-RFI condition when it becomes wavy (not shown in these images). Can anyone suggest why I'm not getting good results with the Airspy Mini? As I believe maybe I'm doing something wrong.

Thanks

HackRF without Monitor RFI: 

Airspy without Monitor RFI: 

HackRF with RFI: (Monitor ON)

Airspy Mini with RFI:

[Alex P]

The config for the ASMini sets the signal power level @ 4X that of the HRF   so you would expect a Higher RFI signal ?

[b alex pettit jr]

Due to the higher gain , perhaps out of band RFI is causing clipping/saturation = higher apparent RFI ?

[Ayushman Tripathi]

Hi Alex,

Yes, possibly. I've observed this several times with my setup, the airspymini sometimes doesn't even show the RFI, just a flat spectrum with small wavy repeating structures. Once the RFI is reduced, it starts working again. The HackRF, however, keeps working fine and clearly detects the H-line. I'll test more. 

I'll share that wavy spectrum image soon.

Thanks. 

[b alex pettit jr]

The Hack has that mid band notch that I prefer to Not have in my data 

Remove the source of  RFI 

it also causes saturation/blocking  non linearity in the LNA amps ( that is not apparent in a spectral display

[Ayushman Tripathi]

Hi Alex,

Yes, for sure the effort should be in reducing the RFI because once it saturates the LNA front-end, no amount of software processing can recover the signal, but I wanted to share this as an observation because sometimes RFI can't be controlled (e.g., from neighbors).

The HackRF's DC spike can be fixed using calibration (e.g., like VIRGO does in the above plot) or by offsetting the center frequency away from the target, but yes it's always better to not have it in the first place.

I'll work on reducing the RFI, but as a test I'll post longer observations using both SDRs with and without Monitor/PowerStation RFI.

Thanks

[b alex pettit jr]

The overall background level has shifted upward : much more with the ASmini

Less with the Hack

Reduce the Gain of the AS mini so the non RFI levels of it matches the Hack ( from -23 dB to -28 dB ) and ReTest

[Stephen Arbogast]

All....  I finally  solved my major RFI problem  by placing my older  iMac  from 2012  between my  Dell  monitor  and my  dish.

See...  photo

I  still occasionally  get  RFI  from neighbors.  Oh well.

[andrew....@googlemail.com]

Is the older Mac turned on or acting just as barrier?

 

From: 'Stephen Arbogast' via Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Sent: 26 January 2026 23:31
To: Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Subject: Re: [SARA] Re: Observation: Airspy Mini and HackRF One under my local RFI and non-RFI conditions

 

All....  I finally  solved my major RFI problem  by placing my older  iMac  from 2012  between my  Dell  monitor  and my  dish.

See...  photo

I  still occasionally  get  RFI  from neighbors.  Oh well.

 

 

On Monday, January 26, 2026 at 11:27:50 AM UTC-7 b alex pettit jr wrote:

The overall background level has shifted upward : much more with the ASmini

 

 

 

Less with the Hack

 

Reduce the Gain of the AS mini so the non RFI levels of it matches the Hack ( from -23 dB to -28 dB ) and ReTest

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[Stephen Arbogast]

My older iMac  is  not  turned on  and not  plugged in,  not  even  grounded.

If one  does not have  an old iMac  I think  some  wire mesh screen  would  work just  as well.

[Stephen Arbogast]

I  have  had  the  same problem  with my HackRF One, turn the  gain   down  to avoid  distortion.

[Stephen Arbogast]

HackRF  One  was not meant to be a weak  signal  device  even  with a  low  noise figure   LNA  in front.

It works  fine  for  exploring  and  experimenting  with strong terrestrial  signals.  

[Stephen Arbogast]

Thus  the name  HackRF

[Stephen Arbogast]

As  I recall  HackRF  was not meant  to be used with  an  LNA, too much  gain causes distortion.  Great  if you are  a Rock  guitar  player!

[Stephen Arbogast]

If  you  want  overdrive  and  distortion  try  this  circuit ..   I  built  one  and it sounds  great!

https://www.google.com/url?sa=t&source=web&rct=j&url=https%3A%2F%2Frobrobinette.com%2FHow_Amps_Work.htm&ved=0CBYQjRxqFwoTCNiuy_zNqpIDFQAAAAAdAAAAABAH&opi=89978449

[Stephen Arbogast]

[Stephen Arbogast]

Mine  is  the  Fender  5C1

[Stephen Arbogast]

A sample....   https://www.youtube.com/watch?v=a3mqDspcgtM

[Stephen Arbogast]

Sound sample..   https://www.youtube.com/watch?v=bf7SmWjWXPQ

[Stephen Arbogast]

In summary...   do not  use an LNA  with  HackRF... lower  the  gain  in  your  HackRF.

[Stephen Arbogast]

HackRF  is not  the  best  choice  for   noise figure.

[Stephen Arbogast]

What is  a  parametric  amplifier?   How  dos  it  work?

[Stephen Arbogast]

If  anyone  has  too much  snow  please send   some to us in Colorado.....

[Alex P]

IF You Can See The Feed, It Can See You & Your Surroundings

                                                     Surround The Dish With Window Screen to act as a Faraday Shield against RFI Reception

[Stephen Arbogast]

In my  case  not  necessary....     the second reflector  is   at  the focal point  of  my   dish   which   reflects  into  the   dipole   which   feeds  into   the     LNA....

[Stephen Arbogast]

90 %  of  the  time  no   problem...     

[b alex pettit jr]

incorrect

The "Reflector" may enhance the intended signal, but it Does Not Prevent Extraneous Signals from Being Received by the Feed Pattern

And being they are 10000X stronger than H Line .. they don't need to be Focused to Overwhelm the data

(   there is lessened reception in-line with the dipole length ... but not much )

[Stephen Arbogast]

The only  time   have   an  RFI problem is   about   10  %   some neighbor  runs  an appliance that   causes  problems.

[Stephen Arbogast]

Totally   disagree   with  you.... 

[Stephen Arbogast]

Problem  solved.. neighbor    running    cheapo  Bluetooth    device....

[Ayushman Tripathi]

Hi Stephen, Alex

Even though the HackRF is less sensitive, I'm observing (for my setup) that the Airspy Mini often struggles to clearly detect the H-line, even when slight RFI is present (at max gain - I'll test with reduced gain soon). The HackRF, however, consistently detects it well. The attached plot is from my 6-hour observation last night using the HackRF One.

Over the past month, I've noticed several instances where the Airspy Mini couldn't detect even a faint H-line, while the HackRF detected it consistently (as shown in my previous message). Sometimes when RFI levels get very high, the Airspy Mini stops showing even the RFI itself, yet the HackRF still detects the H-line.

I'm not sure why this happens, but my guess is that the Airspy Mini's higher sensitivity makes it more susceptible to RFI saturation, whereas the "deafer" HackRF handles it better.

By the way, I'm using the latest official HackRF One. Which HackRF do you have ? You can try testing same by turning your monitor on or off ( OR by removing that iMac :) )

ayushman@ayushman-i914900KS:/mnt/extra$ hackrf_info
hackrf_info version: 2024.02.1
libhackrf version: 2024.02.1 (0.9)
Found HackRF
Index: 0
Serial number:
Board ID Number: 2 (HackRF One)
Firmware Version: 2024.02.1 (API:1.08)
Part ID Number:
Hardware Revision: r10
Hardware appears to have been manufactured by Great Scott Gadgets.
Hardware supported by installed firmware:
    HackRF One

Thanks.
Attached are the plots from tonight's HackRF observation: 

Key Components:

Tuner
HackRF One: RFFC5071/2 + MAX5864
Airspy Mini: R820T2
ADC
HackRF One: MAX5864 (8-bit)
Airspy Mini: LPC4370 (12-bit)
Front-end LNA
HackRF One: MGA-81563 (switchable)
Airspy Mini: R820T2 internal

[Ayushman Tripathi]

And to fix the HackRF drift issues, I'm getting one of these OCXOs, as I can't find a cheap GPSDO.

[b alex pettit jr]

Hello Ayushman,

An Idea :

Run the AS Mini under  SDR#  and observe the real time spectra w/ w/o RFI  to validate the  Virgo Software .

 You should see the same background shifts / spikes 

( setup here )

HLine3D/21cm_Step2C_Software_SDR#_Setup_01_13Jul25.pdf at main · AP-HLine-3D/HLine3D

[b alex pettit jr]

w/ SDR#,   there are 3 gain settings available using the "Free" mode

[Stephen Arbogast]

I cannot  be  of  any   help   here    I  run   Air Spy  on   Linux.......

[Ayushman Tripathi]

Hi Alex,

Sure, I already have SDR# + IF Average set up. I’ll retest the Airspy Mini on that and share the results, though last time I tried I had similar issues. Also, it’s not only with VIRGO - I’ve seen the same issue with SDRangel sometimes. The Airspy Mini can’t detect the H-line, while the HackRF keeps seeing it even when pointing at very faint source.

Thanks

[Ayushman Tripathi]

Hi Stephen,

Yes, I also use it on Linux as it’s easier to automate for long-term observations and can run on remote setups like the Raspberry Pi 5. Also, it’s much easier to see and modify the source code - for example, I modified (Open Source) VIRGO to save the median-filtered data separately. I can try the .grc you made soon.

I think in my local environment the Airspy Mini is getting oversaturated, while the HackRF’s lower sensitivity prevents that. The RTL-SDR showed similar results to the HackRF.
Thanks

On Tuesday, January 27, 2026 at 6:06:31 PM UTC+5:30 Stephen Arbogast wrote:

[b alex pettit jr]

Hi Ayushman,

You may have identified the problem .. being the dynamic range of the Mini  ( OR the gain set by the software )

FYI,

I did an analysis of the AS Mini using a band limited RF radiated noise source into the Antenna > LNA > SDR.

The amplitude of the noise source was adjusted  into soft clipping at about +6dB above 290K Earth equivalent ( from tests )

and a series of nooelec SMA attenuators added to the input of the ASMini

Mini set to Max Gain as shown on previous post

results

[Stephen Arbogast]

HackRF      not for   radio  astronomy...   

[Stephen Arbogast]

You  must     adjust  the  gain    carefully  ..    will  be  spurs  that    that  you    remove   carefully  using ezCon.

[Ayushman Tripathi]

Also, it's not only the HackRF - the NESDR behaves similarly and was able to detect the H-line even when the Airspy Mini couldn't.

I found some examples of HackRF being used for radio astronomy:

SETI work:

• https://seti.net/Operations/Operations.php
• https://www.rtl-sdr.com/searching-for-extraterrestrial-intelligence-seti-with-a-hackrf/

(The setup diagram is from the above post.)

Hydrogen line observations by Wolfgang Herrmann and the Astropeiler Hydrogen Team:

• https://astropeiler.de/wp-content/uploads/2020/01/Hydrogen_4.pdf

Thanks

[Ayushman Tripathi]

Hi Alex,

Do you observe the same when you turn on your monitor nearby? It would be interesting to compare results between the NESDR or if you have a HackRF One/Pro and Airspy-mini under those conditions.

It would be useful for others to know which SDR performs much better in RFI environments. (Of course, the Airspy should be better under NON-RFI conditions)

I'll run more tests with and without RFI and share the results soon.

Thanks

[b alex pettit jr]

My acquisition  PC is ~ 15 meters from the location where I setup my dish / yagi, etc antennas.

I have ~ 1m square of perforated aluminum panels set up behind the PC to block the RF from the notebook monitor. and this is 100% effective .

However I have a another PC with a 32" 4K monitor which ( strangely ) works noise free when  active, but generates Huge RFI spikes when it enters

a power down / standby state .. Meaning,  check my emails & turn it off  when I am acquiring data with the other ..( this monitor is also 15m from the antenna )

I have found no method which shields this RFI other than Power Off

In all cases,  orienting the monitor such that it is Edgewise to the Antenna creates the least interference ..

I use an AirSpy mini for all measurements : it is located at the antenna,  within a thermally stabilized aluminum enclosure and the

USB signal is carried over a fiber optic cable = no digital cabling near the antenna

Here is the setup for the Kraken Discovery Feed.evaluation  ( yellow wire = bidirectional single fiber )

" It would be useful for others to know which SDR performs much better " 

The problem IS it would be quite difficult to define the amplitude and frequency(s) of the RFI causing your problems,

 so any data you derive may not be applicable to others.

Best Solution : try to mitigate the Noise 

Alex

====================================================

On Tuesday, January 27, 2026 at 08:00:53 PM EST, Ayushman Tripathi <ayushmantr...@gmail.com> wrote:

Hi Alex,

Do you observe the same when you turn on your monitor nearby? It would be interesting to compare results between the NESDR or if you have a HackRF One/Pro and Airspy-mini under those conditions.

[b alex pettit jr]

Hi Ayushman,

If this is the setup you are using for these tests, the low elevation angle allows for a Large spillover of RF from everything nearby,

and the mesh even allows RFI to be received through the dish's grid slots ..

Try

  lining the dish with aluminum foil 

  pointing higher in the sky 

  moving the dish close to the outer edge of the porch and

  orienting the dish such that the longer edge  points towards your building to 'shield' some of the RFI

     ( & perhaps testing different orientations to minimize pickup )

Regards,

Alex P

[Ayushman Tripathi]

Hi Alex,

Yes, the above results are from my small WiFi dish setup with the Discovery Dish feed. I'll do some adjustments to make it more RFI-proof, though I've already covered the back of the dish with thick aluminum foil as you suggested.

But I was primarily trying to generate more RFI :) to find out which SDR performs better - just out of curiosity, because when a neighbor turns on their TV, for example, I'll have no control over that.

For my larger 2.5 meter setup with SAWbird and cantenna, the last time I visited that location I didn't have enough time to mitigate the RFI. I'll be going there next week and will wrap the UPS, Pi battery, power bricks, and LTE modem (apart from it's antenna) in foil.

I've noticed that my larger setup is able to detect the H-line at different velocities, while my WiFi dish cannot. I'll run more observations and publish here once I reduce the RFI at the remote site next week.

The attached plot is from my 2.5m dish setup - you can see the RFI. I'll try fixing that next week.

Thanks

[b alex pettit jr]

Hi Ayushman,

It is the Environment in which you are operating the small WiFi dish based system

Not the Hardware.

Alex

======================================================

Hi Alex,

Yes, the above results are from my small WiFi dish setup with the Discovery Dish feed. I'll do some adjustments to make it more RFI-proof, though I've already covered the back of the dish with thick aluminum foil as you suggested.

But I was primarily trying to generate more RFI :) to find out which SDR performs better - just out of curiosity, because when a neighbor turns on their TV, for example, I'll have no control over that.

For my larger 2.5 meter setup with SAWbird and cantenna, the last time I visited that location I didn't have enough time to mitigate the RFI. I'll be going there next week and will wrap the UPS, Pi battery, power bricks, and LTE modem (apart from it's antenna) in foil.

I've noticed that my larger setup is able to detect the H-line at different velocities, while my WiFi dish cannot.

 I'll run more observations and publish here once I reduce the RFI at the remote site next week.

The attached plot is from my 2.5m dish setup - you can see the RFI. I'll try fixing that next week.

Thanks

[Ayushman Tripathi]

Hi Alex,

Yes, reducing the gain a bit did help with the Airspy, but for now I'm getting better results using the HackRF for my smaller setup, so I'll stick with it for a while and then compare with results from the NESDR.

I'll take the Airspy to my larger dish setup, as that location has very little RFI - the Airspy should perform much better there.

Thanks.

[Ayushman Tripathi]

Also, I'll try this compass and see if it helps with better dish pointing.

[Stephen Arbogast]

Some comments....   Ayushman,

It is  the front  end that  is very important..

1.   Location ....  away  from  noise/RFI  sources.  Shield your   monitor from  antenna  at the sight  of your monitor.   Some leakage will occur  but  inverse  square  law  will  help.

2.   Signal to  noise  ratio  is   extremely   important in a   given bandwidth.  Keep  bandwidth   to  what   you  need.  Sample  rate  should  be a minimum  of twice   the   bandwidth...  Nyquist   sampling  rate.  I use 2.5 M  samples per sec with my  Airspy.

3,   Low  noise  figure  of  LNA.  My  Kracken  RF   feed  LNA has noise  figure  spec'ed at .3 db

4.  Don't overload  the  input to your   SDR.

5.   My  own  experience has  been   that  a  HackRF  is not  good for  receiving  weak  signals.... has a high gain with  very  noisy front   end subject   to overload            and distortion when  driven  too  hard. Should  not use  an LNA in  front  of it.

Just  my experience.

Stephen

[Ayushman Tripathi]

Hi Stephen,

Thanks! Yes, my smaller setup is using the exact same Discovery Dish feed. Yes, I agree with you on the HackRF. I've read in many places that the HackRF is not good for weak signals and is considered "deaf," but I'm puzzled as to why the HackRF is giving me better results than both the Airspy and NESDR (not much different from the NESDR, but slightly better).

What do you think could be the reason for this? From what I understand, the HackRF should overload more easily than the Airspy, but I'm seeing the opposite, the Airspy gets overloaded well before the HackRF even starts to show the H-line weakening.

If you're free this weekend, I'd be happy to show you this behavior. Maybe we can figure out why this is happening? And we can compare using SDRAngel.

Also, I'll test with your .grc soon.

I'm also working on reducing the RFI.

Thanks.

[Ayushman Tripathi]

Hi Alex,

Did you use the version of IF Average that has the option to read and save calibrations? I'm observing some issues with that version.

I was trying to use it to check if SDR# has better support for the Airspy, as it may have proprietary drivers for it.

Thanks

[b alex pettit jr]

 SDR#   IS   Airspy SDR# Studio  software = it is 100% compatible .

I never use the save/recall calibration .. It 'should' work but recently  there have been some compatibility issues with the latest MS  DotNET. 

IFavg  will soon be updated.

 Info HERE  links to the software and setup guide

https://github.com/AP-HLine-3D/HLine3D

Regards,

Alex P

[b alex pettit jr]

Another Idea :

The PATH must exist before saving data .. it probably Also needs to be defined before saving the Background Cal 

[Ayushman Tripathi]

Hi Alex,

Thanks. Here's what I got from the Airspy in SDR# + IF Average, Airspy in SDRangel, and the HackRF in VIRGO.

Thanks

[b alex pettit jr]

Hi Ayushman,

Did you notice SDR# supports HackRF ?

Alex

=======================================================

On Sunday, February 1, 2026 at 08:12:41 PM EST, Ayushman Tripathi <ayushmantr...@gmail.com> wrote:

Hi Alex,

Thanks. Here's what I got from the Airspy in SDR# + IF Average, Airspy in SDRangel, and the HackRF in VIRGO.

[Ayushman Tripathi]

Hi Alex,

Yes, it does support HackRF, but from what I remember, SDR# only supports a 10 or 8 MHz sample rate for HackRF, and also, it has no decimation support for it.

Thanks.

[b alex pettit jr]

Clearly,  There is an RFI environment limiting the functioning of the AirSpy SDR.

That the HackRF "works"  does not quantify  How Well the overall system is performing.

Meaning, is the LNA also impaired ( overloaded ) by the adverse RF environment  ?

This may be an H-Line spectrum, but it does not necessarily show a meaningful one.

Alex

=======================================================

On Sunday, February 1, 2026 at 08:12:41 PM EST, Ayushman Tripathi <ayushmantr...@gmail.com> wrote:

Hi Alex,

Thanks. Here's what I got from the Airspy in SDR# + IF Average, Airspy in SDRangel, and the HackRF in VIRGO.

Thanks

.

[Stephen Arbogast]

An  RFI  environment  does not  limit  the  functioning  of an SDR..  it is  the   front end  LNA  that  might  be  overloading. When  I was  playing   with  HackRF    I found   that  I could not   use an  LNA   with it and even  so I had to  turn  down the  gain of the   HackRF   to  avoid   spurs.

[Stephen Arbogast]

Some  cool  stuff   about  GNU  Radio....If  you  can't  find  the  blocks you    want write  your  own.....   

See......  https://www.gnuradio.org/doc/doxygen-3.7/page_python_blocks.html

[Ayushman Tripathi]

Hi Stephen,

As a test, can you test your DD Feed and DD Dish setup on HackRF and Airspy and share the results? 5 mins integration will be enough on SDRangel to compare quickly.

So we can compare the difference, also I'm using this software for HackRFOne:

hackrf_info version: 2026.01.1

libhackrf version: 2026.01.1 (0.9.1)

Found HackRF

Board ID Number: 2 (HackRF One)

Firmware Version: 2026.01.2 (API:1.09)

Hardware Revision: r10

Hardware appears to have been manufactured by Great Scott Gadgets.

Hardware supported by installed firmware:

HackRF One

There are 11 other devices on the same USB bus.

You may have problems at high sample rates.

[Ayushman Tripathi]

Hi Alex,

I think I'm fairly sure it's the H-line, as I've verified by pointing at different parts of the sky - even changes of 10-15° make it disappear. It also consistently appears at the specific times when the dish is pointed at the Milky Way arms.

It can't be coincidence for an unusual RFI bump (which is normally ultra narrow) to match the H-line structure across every astronomical pointing and timing every day.

Yes I think Airspy gets highly effected by it due to it's high senstivity. Anyways I'll do an Airspy test with my bigger dish soon (much less RFI at that location).

Thanks

[b alex pettit jr]

Ayushman,

Try reducing the Gain of the AS mini ... 5, 10, 15 dB and compare the results   see if the H to cold sky improves.

Another Recommendation :

Take the AS mini system to a local park,  a neighbor's  house away from the city, etc  and test it there  .

This will verify the System is performing properly in a good environment

                                                           Your hardware is equivalent to mine   

                                    Your System                                                                                               My System 

Alex

[Ayushman Tripathi]

Hi, Alex.

Okay, also I fixed my Virgo custom script today to work with Airspy gains, so I'll also test with Virgo and the Airspy tomorrow using Virgo's calibration and will see if I get results similar to the HackRF.

Thanks.

[Stephen Arbogast]

AirSpy - HackRF  Comparison,  data collected at same time of day one day apart using GNU Radio Radio Radiometer

hackrf_info version: 2023.01.1
libhackrf version: 2023.01.1 (0.8)
Found HackRF
Index: 0
Serial number: 000000000000000087c867dc2b60895f

Board ID Number: 2 (HackRF One)

Firmware Version: 2023.01.1 (API:1.07)
Part ID Number: 0xa000cb3c 0x0060475c
Hardware Revision: older than r6

Hardware supported by installed firmware:
    HackRF One

Ayushman, my HackRFOne  is  in a plastic case  and I observed the base noise moved up and down  as I moved it  around my desk!!   not good

[Ayushman Tripathi]

Hi Stephen,

I've shielded my HackRF One by keeping it inside a sealed aluminium thick foil wrapped box with a small hole for the wires. It was very noisy in it's plastic case that it was almost unusable.

Also, HackRF has two other gain stages besides RF Gain - IF Gain and BB Gain. Did you keep those at default, or did you adjust them? For my setup, I keep the HackRF at max gain with AMP enabled: RF Gain = 14 dB, IF Gain = 40 dB, BB Gain = 62 dB.  https://hackrf.readthedocs.io/en/latest/setting_gain.html

If you get time maybe you can try a quick test using SDRangel that produces similar results for me with HackRF & Airspy just HackRF handling RFI better.

Today I tried VIRGO with the Airspy and got better results, I didn't got much time to test properly today, And I wasn't pointing directly at a source when I took the plot below,  just near enough as it was too late for the target elevation. Still, it seems better. I'll do a proper VIRGO calibration and test more soon.

Airspy with VIRGO:

Thanks.
That VIRGO plot is while the dish was pointing here:

[Stephen Arbogast]

Sorry,   I did not report gain settings  for  my  HackRFOne.    My  flow  graph  has  both  blocks  for  AirSpy  and HackRFOne  sources  so  here it  is for viewing the  settings.

My  HackRFOne  is  a bit older  than  yours  so maybe  yours  works  better than mine.   With  respect,  I  see no reason  to use  my HackRFOne  for  radio  astronomy or  other  weak signal  observations.   It was  my first SDR   and it is still  great  for "hacking"  not  for weak signals.  I  think  keeping  gain settings  at maximum  will  cause  overload and  distortion.

Stephen

[Ayushman Tripathi]

Hi,

I moved my Airspy to my 2.5 meter dish setup, the response looks much cleaner now, as this location is far from the city.
I’ll share the results soon. I’ll keep the Airspy at this setup from now on. For the smaller dish setup, I’ll use the NESDR and HackRF for quick tests.

Thanks​​

[Ayushman Tripathi]

Hi, With my 2.4 meter dish at this remote setup my Airspy is working great and getting better results than the NESDR, Here are some plots, I’ll run long tests tomorrow. I also replaced the old cable with a thick LMR-400 cable at the remote site, running from the SAWbird LNA at the cantenna feed to the SDR.

Thanks 

Sent from my iPhone

On 7 Feb 2026, at 08:10, Ayushman Tripathi <ayushmantr...@gmail.com> wrote:

Hi,

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[Stephen Arbogast]

Very cool  Ayushman,   progress   through  experiments.

I thought  I had collected  24 hours  of drift scan  using my  modified  GNU Radio Spectro Radiometer  but  I had two  problems.   I started  the file  data collection   before  my  electronics  was fully  warmed up and my neighbor  started up  his old  gas powered  rototiller   thus    noise  at first in the  first  file. So  I ran  ezRACon  on the  second  file  and  got  some  results.  I need practice putting together  a report   so  I  started  learning   Libre  Office  ....  I'm  not  good  at  it  but  I will attach  my first  attempt.

Now  that  am  convinced  my GNU Radio  Spectro Radiometer is   working I want to concentrate on learning  Ted  Cline's ezRA   analysis  software.  Again  I will attach my  first  attempt so one gets  the idea but don't  take it  seriously....

Stephen

[b alex pettit jr]

Hello Ayushman,

I can not make a quantitative evaluation of your results as we do not use similar software.

For Reference :

The Data is from Drift Scan slices @ Declination + 40 Degrees

( peak energy at RA 20:30Hrs )

====================================================

This is Data from a  2.3m and 2.5m dish

Comparing Your 2.4m Data to my 1.2m Dish  ( Frequency Scales Matched  )

Comparing Your 2.4m Data to my 1.2m Dish  ( Frequency Scales Matched  but plot Shifted so peaks are aligned )

Alex

===========================================

On Saturday, February 7, 2026 at 06:46:23 PM EST, Ayushman Tripathi <ayushmantr...@gmail.com> wrote:

Hi, With my 2.4 meter dish at this remote setup my Airspy is working great and getting better results than the NESDR, Here are some plots, I’ll run long tests tomorrow. I also replaced the old cable with a thick LMR-400 cable at the remote site, running from the SAWbird LNA at the cantenna feed to the SDR.

Thanks 

[Ayushman Tripathi]

Hi Alex,

Yes, I think the data in your plots is obtained after calibration in IF Average, while the raw spectrum shown in VIRGO is uncalibrated. However, VIRGO also displays calibrated data. For calibration, I used cold sky, you can check the calibrated plots in the VIRGO output, which should be a better comparison.

I can’t run SDR# on my remote setup even if I wanted to, as it’s running on a Raspberry Pi with Linux. But I think the calibrated spectrum should be a better comparison.

Also soon I'll do a long observation and share the data.

The attached plots are the Virgo’s calibrated spectrum I obtained today: RA 18h 30m, Dec -09° 22’  

Thanks

On 8 Feb 2026, at 16:30, 'b alex pettit jr' via Society of Amateur Radio Astronomers <sara...@googlegroups.com> wrote:



Hello Ayushman,

I can not make a quantitative evaluation of your results as we do not use similar software.

For Reference :

The Data is from Drift Scan slices @ Declination + 40 Degrees

( peak energy at RA 20:30Hrs )

====================================================

This is Data from a  2.3m and 2.5m dish

<1770546290918blob.jpg>

Comparing Your 2.4m Data to my 1.2m Dish  ( Frequency Scales Matched  )

<1770547952736blob.jpg>

Comparing Your 2.4m Data to my 1.2m Dish  ( Frequency Scales Matched  but plot Shifted so peaks are aligned )

<1770548045146blob.jpg>

Alex

===========================================

On Saturday, February 7, 2026 at 06:46:23 PM EST, Ayushman Tripathi <ayushmantr...@gmail.com> wrote:

Hi, With my 2.4 meter dish at this remote setup my Airspy is working great and getting better results than the NESDR, Here are some plots, I’ll run long tests tomorrow. I also replaced the old cable with a thick LMR-400 cable at the remote site, running from the SAWbird LNA at the cantenna feed to the SDR.

Thanks 

<obs_0031_20260208_005613_plot.png>

Sent from my iPhone

On 7 Feb 2026, at 08:10, Ayushman Tripathi <ayushmantr...@gmail.com> wrote:

Hi,

I moved my Airspy to my 2.5 meter dish setup, the response looks much cleaner now, as this location is far from the city.
I’ll share the results soon. I’ll keep the Airspy at this setup from now on. For the smaller dish setup, I’ll use the NESDR and HackRF for quick tests.

Thanks​​

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<1770546290918blob.jpg>

<1770547952736blob.jpg>

<1770548045146blob.jpg>

<obs_0031_20260208_005613_plot.png>

[b alex pettit jr]

Hi Ayushman,

These look much better.

Alex

[b alex pettit jr]

Use this as a reference for the spectra 

Argelander Institut für Astronomie - HI Profile Search

Argelander Institut für Astronomie - HI Profile Search

==============================================================================

[Ayushman Tripathi]

Hi, Alex.

Sure, thanks.

[Ayushman Tripathi]

Hi Stephen,

Thanks! I’ll test your spectrometer using data from my remote station.

Your data looks similar to mine, and your report is good. Just curious, does it have cold-sky calibration yet? From what I observed with VIRGO and IF Average, calibration helps a lot.

Do you plan to add/test calibration later, or have you already added it but didn’t include it in the report?

Thanks.

[Stephen Arbogast]

No, I did not record a background reference...that is next.