Date   
Re: Gain control #HF+

jdow
 

1) Is this with a 50 ohm dummy load attached?
2) Better, is this with a low noise signal generator set to about -70 dBm IN the band of measurement attached?
3) Do you know what you are measuring?
4) Do you know how to interpret what you are measuring?
5) Do you know what measurements matter?

Item 2 is the way you are going to get the best measurements for the AirSpy HF+'s noise floor. If you have a REAL antenna for HF use, do you realize that AirSpy HF+ noise is the LEAST of your noise problems, some of which are endemic to a real world environment within this universe at approximately this distance from a furiously radiating fusion heat generator?

{o.o}

On 20180313 06:01, Pete Smith wrote:
I am trying to use my Airspy to qantitatively assess the noise environment at my QTH, and I'm seeing what seem to be significant gain variations between the ham bands and other frequencies.  Is this the case, and are there provisions for setting up a flat profile as well?
73, Pete N4ZR
Check out the Reverse Beacon Network
at<http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.
On 3/13/2018 8:47 AM, prog wrote:
On Tue, Mar 13, 2018 at 05:33 am, Giovanni Carboni wrote:

I did not check carefully


Please check VERY carefully the gain settings. Different firmwares will have different settings.

Re: USB cable quality and QRM in a spyserver setup with an Airspy Hf+ and Raspberry PI3. 6 microUSB cable test. #airspyhfplus #bestpractice #raspberrypi

Dana Myers
 

On 3/13/2018 6:42 PM, Pete Smith wrote:

Can you elaborate, Dana.  What were the characteristics of the noise that was helped by changing out the cable?  I ask because my shack is full of USB cables and I have suspicions about their contribution to my noise floor.


It came in various forms.

More innocuous noise was seen as repetitive spikes in the waterfall.
It made me think I had a monitor or TV leaking into my actual receiving
antenna and it was pretty much everywhere on HF.

For a 2-pack of 10' cables, $17 on eBay was a deal.

73,
Dana  K6JQ




Re: USB cable quality and QRM in a spyserver setup with an Airspy Hf+ and Raspberry PI3. 6 microUSB cable test. #airspyhfplus #bestpractice #raspberrypi

Pete Smith <n4zr@...>
 

Can you elaborate, Dana.  What were the characteristics of the noise that was helped by changing out the cable?  I ask because my shack is full of USB cables and I have suspicions about their contribution to my noise floor.

73, Pete N4ZR
Check out the Reverse Beacon Network 
at <http://reversebeacon.net>, now 
spotting RTTY activity worldwide. 
For spots, please use your favorite 
"retail" DX cluster.
On 3/13/2018 5:57 PM, Dana Myers wrote:

Thank you very much for sharing this research. I noted a substantial improvement in RFI when I replaced my no-name cable with a Volutz cable. Just brilliant information.

Thanks and 73,
Dana  K6JQ

Re: Gain settings with Firmware 1.6.2 #airspyhfplus #firmware #bestpractice

Gary_Gagnon@...
 

Hi Simon

I'll soon need to provide for more dog food!  AGC Low got things useable again for 2.5 MHz and lower.

Thanks
Gary


From: "simon" <simon@...>
To: main@airspy.groups.io
Sent: Tuesday, March 13, 2018 4:00:18 PM
Subject: Re: [airspy] Firmware 1.6.2: intermod problem Airspy HF+

Gary,

 

I posted a kit with full AGC / ATT / Preamp access.

 

32-bit

https://www.dropbox.com/s/0np36044smb6yys/SDR-Radio%20V3%2C%2032-bit%2C%202018-03-11_1049.exe?dl=0

 

64-Bit

https://www.dropbox.com/s/8395nb70y93jba7/SDR-Radio%20V3%2C%2064-bit%2C%202018-03-11_1046.exe?dl=0

 

 

Simon Brown, G4ELI
www.sdr-radio.com

 

 

From: main@airspy.groups.io <main@airspy.groups.io> On Behalf Of Gary_Gagnon@...
Sent: 13 March 2018 22:32
To: main@airspy.groups.io
Subject: Re: [airspy] Firmware 1.6.2: intermod problem Airspy HF+

 

Hi info

 

I found that with 1.6.2 and SDR-Console (with no user control access) that 2.5MHz and lower is pretty well useless now due to AM Broadcast band overload (I think it's AM broadcast).

 

I went back to airspy-hf-flash-20180225 which works well enough.

 

GaryG in Vancouver, BC

 

Re: Gain settings with Firmware 1.6.2 #airspyhfplus #firmware #bestpractice

Simon Brown
 

From: main@airspy.groups.io <main@airspy.groups.io> On Behalf Of Gary_Gagnon@...
Sent: 13 March 2018 22:32
To: main@airspy.groups.io
Subject: Re: [airspy] Firmware 1.6.2: intermod problem Airspy HF+

 

Hi info

 

I found that with 1.6.2 and SDR-Console (with no user control access) that 2.5MHz and lower is pretty well useless now due to AM Broadcast band overload (I think it's AM broadcast).

 

I went back to airspy-hf-flash-20180225 which works well enough.

 

GaryG in Vancouver, BC

 

 


From: "info" <info@...>
To: main@airspy.groups.io
Sent: Tuesday, March 13, 2018 5:47:52 AM
Subject: Re: [airspy] Firmware 1.6.2: intermod problem Airspy HF+

 

On Tue, Mar 13, 2018 at 05:33 am, Giovanni Carboni wrote:

I did not check carefully


Please check VERY carefully the gain settings. Different firmwares will have different settings.

Re: Gain settings with Firmware 1.6.2 #airspyhfplus #firmware #bestpractice

Gary_Gagnon@...
 

Hi info

I found that with 1.6.2 and SDR-Console (with no user control access) that 2.5MHz and lower is pretty well useless now due to AM Broadcast band overload (I think it's AM broadcast).

I went back to airspy-hf-flash-20180225 which works well enough.

GaryG in Vancouver, BC



From: "info" <info@...>
To: main@airspy.groups.io
Sent: Tuesday, March 13, 2018 5:47:52 AM
Subject: Re: [airspy] Firmware 1.6.2: intermod problem Airspy HF+

On Tue, Mar 13, 2018 at 05:33 am, Giovanni Carboni wrote:
I did not check carefully

Please check VERY carefully the gain settings. Different firmwares will have different settings.

Re: Gain settings with Firmware 1.6.2 #airspyhfplus #firmware #bestpractice

Roberto Zinelli
 

Giovanni, with 1.6.2 i put  AIRSPY-HF ACG OFF and set attenuator -12 DB,   the overral noise figure for me is better then 1.6.1

On Tue, Mar 13, 2018 at 11:03 PM, Giovanni Carboni <iz5pqt@...> wrote:
Here are three spectra around 738 kHz taken with a) FW 1.6.2;  b) FW 1.6.2 plus an external 20 dB attenuator;  c) FW 1.6.1.
As you see in case a) the reception is totally washed out. The only way to get a reasonable spectrum with 1.6.2 is to turn off the AGC in SDR# and insert a lot of attenuation.

73 Giovanni


Re: Gain settings with Firmware 1.6.2 #airspyhfplus #firmware #bestpractice

Giovanni Carboni
 
Edited

Here are three spectra around 738 kHz taken with a) FW 1.6.2;  b) FW 1.6.2 plus an external 20 dB attenuator;  c) FW 1.6.1.
As you see in case a) the reception is totally washed out. The only way to get a reasonable spectrum with 1.6.2 without the external attenuator is to turn off the AGC in SDR# and insert a lot of HF attenuation from the panel.

73 Giovanni

Re: USB cable quality and QRM in a spyserver setup with an Airspy Hf+ and Raspberry PI3. 6 microUSB cable test. #airspyhfplus #bestpractice #raspberrypi

Dana Myers
 

Thank you very much for sharing this research. I noted a substantial improvement in RFI when I replaced my no-name cable with a Volutz cable. Just brilliant information.

Thanks and 73,
Dana  K6JQ

Re: Airspyhf+ flashing

Albert (PA5OXW)
 

Thanks this info. Followed your clear set on my WIN10 system and all worked out 100% correct. Now getting to know the latest VER .1655 Firmware R1.6.2.

73

Albert

PD0OXW

 

From: main@airspy.groups.io [mailto:main@airspy.groups.io] On Behalf Of WZ2Q
Sent: 10 March 2018 18:05
To: main@airspy.groups.io
Subject: Re: [airspy] Airspyhf+ flashing

 

I put together these instructions a few weeks ago when I updated the firmware from 0.9 (the version from the factory that had the flashing bug) to the latest version. This worked for me on Windows 10.

AirSpy HF+ Firmware Update Instructions

Howard M. Harte, WZ2Q - February 22, 2018

Overview

There are two different flash procedures, depending on the current firmware running in your AirSpy HF+.  If you have never flashed it before, follow the first-time update procedure. These instructions were verified on a Windows 10 PC.  The command prompt window was “run as Administrator” although I’m not sure this is necessary.

First-Time Update (Recovery Procedure:)

 

Due to a bug in the first firmware, this procedure must be used for the first firmware upgrade.

Subsequent updates should work with the standard procedure above.

 

1. Open the HF+ enclosure

2. Connect the device to the PC

3. Short the Erase pins for one second (see the photo)

 

 

4. Disconnect the device from the PC

5. Connect the device again

6. Double click on flash.bat

7. Wait until it flashes and verifies the data

8. Disconnect the device from the PC

9. Connect the device again

10. Done

 

Example Output:

 

C:\airspy-hf-flash-20180222\airspy-hf-flash>FLASH.bat

Airspy HF+ Flash Utility

Looking for a suitable flashable device...

Flashable device found on port COM13

Unlock all regions

Erase flash

 

Done in 0.011 seconds

Write 42140 bytes to flash (165 pages)

[==============================] 100% (165/165 pages)

Done in 2.503 seconds

Verify 42140 bytes of flash

[==============================] 100% (165/165 pages)

Verify successful

Done in 1.879 seconds

Set boot flash true

Rebooting the device in normal mode...

The system cannot find the file Calib.

Restoring the calibration...

Done

Press a key to close.

 

Subsequent Updates (Standard Firmware Upgrade Procedure:)

 

1. Connect the unit to the PC

2. Double click on flash.bat

3. Disconnect the device from the PC

4. Connect the device again

5. Done

 

Example Output

C:\airspy-hf-flash-20180222\airspy-hf-flash>FLASH.bat

Airspy HF+ Flash Utility

Looking for a suitable flashable device...

Looking for a suitable flashing driver...

This one can do the job: \WINDOWS\INF\OEM53.INF

Saving the calibration...

Rebooting the device in flash mode...

Flashable device found on port COM13

Unlock all regions

Erase flash

 

Done in 0.011 seconds

Write 42140 bytes to flash (165 pages)

[==============================] 100% (165/165 pages)

Done in 2.309 seconds

Verify 42140 bytes of flash

[==============================] 100% (165/165 pages)

Verify successful

Done in 1.680 seconds

Set boot flash true

Rebooting the device in normal mode...

Restoring the calibration...

Done

Press a key to close.

 

Re: Remote Flashing airspy HF+ connected to Raspberry pi. #firmware

ea5ehs@...
 

Hallo Alexander,
No, there isn't enough bandwidth in my wifi data link to make it useable.

Best Ni

Re: Airspy noise figure

David Eckhardt
 

Remember the now defunct (sad) publication titled, "Ham Radio"?  It was the best of all amateur radio publication and likely too much for those 'lesser' publications.  The publication made no bones about using the calculus in their articles.   One piece of home brew test equipment that was published in "Ham Radio" was a "Gated Noise Source" (readers can look it up online).  It produced what you describe as an ON/OFF noise source.  I found it extremely useful in tuning for best noise figure AND gain.  With a associated spectrum analyzer (SDR these days), you could view simultaneously, noise performance, gain, and bandwidth.  Quite a tool!  For anyone with a calibrated noise source, the source could be fed through an FET of saturated bipolar switch (0.3 volts drop with the bipolar option) switch.  The transistor was then fed with an audio square wave generator.  Highly useful in dealing with receiving systems and low-noise preamps and filters, and.....

Dave - WØLEV 

On Tue, Mar 13, 2018 at 5:06 PM, doug <dmcgarrett@...> wrote:
There's another method of getting a noise figure number, if you have a
pulsed RF source: carefully adjust the source so that the detected rf
pulse is tangential. What this means is that
the average noise at the bottom of the detected pulse is equal to the
average noise of the baseband, where there is no pulse. The value is
equal to 8dB above signal equals noise. Now if you
know the bandwidth of the receiver, you can determine the noise figure,
since you know that at 1 Hz BW, a perfect receiver would have a
sensitivity of -174 dBm. For every increase in
bandwidth, the s/n ratio decreases by the value ratio. For example, at
1KHz bandwidth, a perfect receiver would have s=n at -144 dBm. This
method is not as precise as a calibrated noise source,
but it's close.

--doug. WA2SAY, retired RF engineer.

On 03/13/2018 05:46 AM, jdow wrote:
Given a choice I'd prefer to try liquid funnygas er Helium for the
cold source.

{^_-}  Just being imaginative and silly again.

On 20180312 09:15, David Eckhardt wrote:
Yes, there is nothing to compete with the hot/cold 'noise' source.
kTB is very specific.  However, knowing the information bandwidth
introduces errors for our amateur receivers unless we rigorously
measure that as well. I've always preferred the hot/cold noise
source, but don't keep LN2 around.  However, these days, most larger
grocery stores carry dry ice.

Dave - WØLEV

On Mon, Mar 12, 2018 at 4:06 AM, Marcus D. Leech <mleech@...
<mailto:mleech@...>> wrote:

    On 03/11/2018 09:00 PM, David Rowe wrote:

        Thanks Dave - sounds like you have a great experimental set
up there for
        NF measurements.  For anyone interested in NF measurements,
I've blogged
        on my humble experiments here:

        http://www.rowetel.com/?p=5867

        I mentioned your results in the post Dave, hope thats OK.

        Cheers,

        David

    I'll point out that single-point noise-figure methods are rather
    error-prone, which is why the industry has standardized on the
Y-factor
    method, in which
       you have TWO sources of known noise power distribution.

    For noise figures above 3dB, you can usually use a high-quality
terminator
    at room temperature -- whose PSD will be -174dBM/Hz, and then a
calibrated
       noise source, usually in the 20-35dB ENR range.  You take
averaged
    measurements of both, and use that to determine the noise figure
of the DUT.

    Once you start going to noise-figures below 2-3dB, it's better to
have a
    "cold load" as one of the noise sources.  Labs that care about
noise figure
       measurements for "good" LNAs usually use an LN2-cooled load
for the
    "cold" load, and again a calibrated noise head for the "hot" load.





        On 12/03/18 10:18, David Eckhardt wrote:

            I have a calibrated noise source good to 18 GHz and several
            precision attenuators (HP, both single value and
switched).  Knowing
            the noise output of the noise source, I attenuate until
the noise
            just goes into the 'noise', tangential noise.  The
difference
            between the noise source known output and the
attenuation  is my
            noise figure.

            Dave - WØLEV

            On Sun, Mar 11, 2018 at 10:27 PM, David Rowe
<david@...
            <mailto:david@...> <mailto:david@...
            <mailto:david@...>>> wrote:

                 Thanks Dave,

                 Could you tell me a little more about how you
measured NF?

                 Thanks,

                 David

                 On 12/03/18 08:37, David Eckhardt wrote:

                     I've measured both the R1 and my present R2.
They both come in
                     around 4 dB.  I believe 7 to 8 dB is a bit much
based on my
                     experience with them.

                     Dave - WØLEV

                     On Sun, Mar 11, 2018 at 9:34 PM, <david@...
            <mailto:david@...>
                     <mailto:david@...
<mailto:david@...>>
            <mailto:david@... <mailto:david@...>
                     <mailto:david@...
<mailto:david@...>>>> wrote:

                          Hi - I've been setting up a system to
measure noise
            figures
                     of SDRs
                          in real time, an extension of some similat
tests we
                     performed a few
                          years ago:

            https://www.rowetel.com/?p=5057
<https://www.rowetel.com/?p=5057>
                     <https://www.rowetel.com/?p=5057
            <https://www.rowetel.com/?p=5057>>
                     <https://www.rowetel.com/?p=5057
            <https://www.rowetel.com/?p=5057>
<https://www.rowetel.com/?p=5057
            <https://www.rowetel.com/?p=5057>>>

                          I'm getting a NF of 7-8dB for a new Airspy
R2 and Airspy
                     mini.  The
                          spec quotes 3.6dB.  Has anyone else
measured the NF?

                          I note the 3.6dB figure is exactly the same
as the front
                     end tuner
                          R820 tuner.  However a system noise figure
will always be
                     poorer
                          than the front end device.

                          Thanks,

                          David




                     --         *Dave - WØLEV
                     *
                     */Just Let Darwin Work/*







            --             *Dave - WØLEV
            *
            */Just Let Darwin Work/*









--
*Dave - WØLEV
*
*/Just Let Darwin Work/*












--
Dave - WØLEV
Just Let Darwin Work

Re: Airspy noise figure

doug
 

There's another method of getting a noise figure number, if you have a
pulsed RF source: carefully adjust the source so that the detected rf
pulse is tangential. What this means is that
the average noise at the bottom of the detected pulse is equal to the
average noise of the baseband, where there is no pulse. The value is
equal to 8dB above signal equals noise. Now if you
know the bandwidth of the receiver, you can determine the noise figure,
since you know that at 1 Hz BW, a perfect receiver would have a
sensitivity of -174 dBm. For every increase in
bandwidth, the s/n ratio decreases by the value ratio. For example, at
1KHz bandwidth, a perfect receiver would have s=n at -144 dBm. This
method is not as precise as a calibrated noise source,
but it's close.

--doug. WA2SAY, retired RF engineer.

On 03/13/2018 05:46 AM, jdow wrote:
Given a choice I'd prefer to try liquid funnygas er Helium for the
cold source.

{^_-} Just being imaginative and silly again.

On 20180312 09:15, David Eckhardt wrote:
Yes, there is nothing to compete with the hot/cold 'noise' source.
kTB is very specific. However, knowing the information bandwidth
introduces errors for our amateur receivers unless we rigorously
measure that as well. I've always preferred the hot/cold noise
source, but don't keep LN2 around. However, these days, most larger
grocery stores carry dry ice.

Dave - WØLEV

On Mon, Mar 12, 2018 at 4:06 AM, Marcus D. Leech <mleech@...
<mailto:mleech@...>> wrote:

On 03/11/2018 09:00 PM, David Rowe wrote:

Thanks Dave - sounds like you have a great experimental set
up there for
NF measurements. For anyone interested in NF measurements,
I've blogged
on my humble experiments here:

http://www.rowetel.com/?p=5867

I mentioned your results in the post Dave, hope thats OK.

Cheers,

David

I'll point out that single-point noise-figure methods are rather
error-prone, which is why the industry has standardized on the
Y-factor
method, in which
you have TWO sources of known noise power distribution.

For noise figures above 3dB, you can usually use a high-quality
terminator
at room temperature -- whose PSD will be -174dBM/Hz, and then a
calibrated
noise source, usually in the 20-35dB ENR range. You take
averaged
measurements of both, and use that to determine the noise figure
of the DUT.

Once you start going to noise-figures below 2-3dB, it's better to
have a
"cold load" as one of the noise sources. Labs that care about
noise figure
measurements for "good" LNAs usually use an LN2-cooled load
for the
"cold" load, and again a calibrated noise head for the "hot" load.





On 12/03/18 10:18, David Eckhardt wrote:

I have a calibrated noise source good to 18 GHz and several
precision attenuators (HP, both single value and
switched). Knowing
the noise output of the noise source, I attenuate until
the noise
just goes into the 'noise', tangential noise. The
difference
between the noise source known output and the
attenuation is my
noise figure.

Dave - WØLEV

On Sun, Mar 11, 2018 at 10:27 PM, David Rowe
<david@...
<mailto:david@...> <mailto:david@...
<mailto:david@...>>> wrote:

Thanks Dave,

Could you tell me a little more about how you
measured NF?

Thanks,

David

On 12/03/18 08:37, David Eckhardt wrote:

I've measured both the R1 and my present R2.
They both come in
around 4 dB. I believe 7 to 8 dB is a bit much
based on my
experience with them.

Dave - WØLEV

On Sun, Mar 11, 2018 at 9:34 PM, <david@...
<mailto:david@...>
<mailto:david@...
<mailto:david@...>>
<mailto:david@... <mailto:david@...>
<mailto:david@...
<mailto:david@...>>>> wrote:

Hi - I've been setting up a system to
measure noise
figures
of SDRs
in real time, an extension of some similat
tests we
performed a few
years ago:

https://www.rowetel.com/?p=5057
<https://www.rowetel.com/?p=5057>
<https://www.rowetel.com/?p=5057
<https://www.rowetel.com/?p=5057>>
<https://www.rowetel.com/?p=5057
<https://www.rowetel.com/?p=5057>
<https://www.rowetel.com/?p=5057
<https://www.rowetel.com/?p=5057>>>

I'm getting a NF of 7-8dB for a new Airspy
R2 and Airspy
mini. The
spec quotes 3.6dB. Has anyone else
measured the NF?

I note the 3.6dB figure is exactly the same
as the front
end tuner
R820 tuner. However a system noise figure
will always be
poorer
than the front end device.

Thanks,

David




-- *Dave - WØLEV
*
*/Just Let Darwin Work/*







-- *Dave - WØLEV
*
*/Just Let Darwin Work/*









--
*Dave - WØLEV
*
*/Just Let Darwin Work/*

Re: Gain control #HF+

Pete Smith <n4zr@...>
 

Can't really quantify.  This is something I encountered while doing a full HF survey for RFI.  I ran into one emitter of clear signals every 8 KHz, and noticed that it jumped up in strength on the ham bands as compared to 1-MHz slices above and below the bands.  What I was wondering is whether the Airspy HF+ has different preamp gains settable by band, or whether gain is supposed to be uniform across the HF range.

73, Pete N4ZR
Check out the Reverse Beacon Network 
at <http://reversebeacon.net>, now 
spotting RTTY activity worldwide. 
For spots, please use your favorite 
"retail" DX cluster.
On 3/13/2018 9:41 AM, prog wrote:

On Tue, Mar 13, 2018 at 06:36 am, Pete Smith wrote:
I'm seeing what seem to be significant gain variations between the ham bands and other frequencies. 

How significant is "significant"? What are the numbers? What is your test setup? And what are your expectations in dB?

Re: Gain settings with Firmware 1.6.2 #airspyhfplus #firmware #bestpractice

Chris Smolinski
 

Yes, I meant the library that the host software uses, not the firmware.

Chris Smolinski
Black Cat Systems
Westminster, MD USA
http://www.blackcatsystems.com

On Mar 13, 2018, at 9:49 AM, prog <@prog> wrote:

On Tue, Mar 13, 2018 at 06:42 am, Chris Smolinski wrote:
Any guesses when there will be a library update to further improve the AirSpyHF+ filtering?

Firmware updates do not affect the IQ correction in any way. The correction is done in the host computer, not in the radio itself.
These firmware updates improve the dynamics of the front end.

Re: Gain settings with Firmware 1.6.2 #airspyhfplus #firmware #bestpractice

prog
 

On Tue, Mar 13, 2018 at 06:42 am, Chris Smolinski wrote:
Any guesses when there will be a library update to further improve the AirSpyHF+ filtering?

Firmware updates do not affect the IQ correction in any way. The correction is done in the host computer, not in the radio itself.
These firmware updates improve the dynamics of the front end.

Re: Gain settings with Firmware 1.6.2 #airspyhfplus #firmware #bestpractice

Chris Smolinski
 

I notice the same levels of intermod on LW/LW with firmware version 1.6.2 vs previous versions, it does not seem any worse. This is using SdrConsole which AFAIK keeps the AirSpyHF+ AGC turned on.

While playing around with SDR# I was of course able to generate lots more intermod/etc by switching AGC off and turning the gains up too high and overloading things, as you'd expect.

I don't have any nearby strong MW stations, the nearest is about 10 miles away, and I think 5 kW. With AGC on I can occasionally see images from it on LW and MW, although careful tuning can eliminate them. (Setting the center frequency such that the station is outside the 768 kHz passband)

Any guesses when there will be a library update to further improve the AirSpyHF+ filtering?

Chris Smolinski
Black Cat Systems
Westminster, MD USA
http://www.blackcatsystems.com

On Mar 13, 2018, at 8:33 AM, Giovanni Carboni <@IZ5PQT> wrote:

Hello everyone,

I had to disinstall version 1.6.2 of the firmware (20180309) on my AirspyHF+ since it caused horrible
intermodulation below 1 MHz.

Less than 15 km from my QTH there is a 50 kW MW TX on 657 kHz (Rai Coltrano). The signal at the
radio antenna input is -21 dBm measured with an ELAD S2 and checked with a scope. The two measurements
agree within errors (20 mV peak on the scope). It is a quite large signal so I am clearly in an extreme
situation.

With all firmware versions until 1.6.1 the receiver did not show intermodulation problems (except of course
for a narrow band around 657 kHz). With 1.6.2 a terrible
intermodulation occurred making reception impossible on all the MW spectrum up to 1000 kHz. I did not check
carefully but it looks like reception below 500 kHz was not affected.

I had to go back to 1.6.1 and things became normal.

I do not have instrumentation to perform more accurate measurements but the test is
easily reproducible in a lab.

73 Giovanni IZ5PQT


Re: Gain settings with Firmware 1.6.2 #airspyhfplus #firmware #bestpractice

Giovanni Carboni
 

Sorry, I had no idea that the firmware parameters were adjustable. Where can I find the instructions to do that?

73 Giovanni

Re: Gain control #HF+

prog
 

On Tue, Mar 13, 2018 at 06:36 am, Pete Smith wrote:
I'm seeing what seem to be significant gain variations between the ham bands and other frequencies. 

How significant is "significant"? What are the numbers? What is your test setup? And what are your expectations in dB?

Gain control #HF+

Pete Smith <n4zr@...>
 

I am trying to use my Airspy to qantitatively assess the noise environment at my QTH, and I'm seeing what seem to be significant gain variations between the ham bands and other frequencies.  Is this the case, and are there provisions for setting up a flat profile as well?

73, Pete N4ZR
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On 3/13/2018 8:47 AM, prog wrote:

On Tue, Mar 13, 2018 at 05:33 am, Giovanni Carboni wrote:
I did not check carefully

Please check VERY carefully the gain settings. Different firmwares will have different settings.