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Messages - RobRich

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Drilled down to narrow bandwidths and extremely high FFTs. 210PPM looks okay IMO. That is not far off my initial number from last night. :)

As I seem to remember experiencing previously, the AM sync algorithm in SDRangel bounces a Hertz or so with my HF+D. Even with the trivial bounce it is averaging around 1Hz deviation, which is the smallest resolution it reports, so it could very well be less than that. The HF+D specs suggest ~0.5PPM precision. Seems to be about what I am getting.

I dropped Airspy.US to see if the shipped calibration is still on file. Mostly just to compare. Might be interesting to see the components have drifted.

I know the Leo Bodnar units are popular for the price with more serious SDR enthusiasts.

That was a quick reply. Original calibration from 2020 was 75. So a little drift, but not enough for me to ever really notice.

You can do similar with SDRangel, which I might get around to later this weekend.

Last night I just did multiple WWV frequencies at various sample rates and very high FFT values. The 2500 screenshot happened to be where the SDR was parked.

I actually have a few devices that can do signal generation, but none are lab grade. Marginally okay for poking at analog radios. Not so much SDRs.

You can pickup a basic GPSDO for under $100 these days, assuming one feeks lucky. ;) YMMV.

Music at 0317z. SINPO 55343. ~S9 via Airspy HF+D and 148' loop-on-ground. DSB sync tuning. Moderate to occasionally strong static crashing, but otherwise a decent copy.

Thanks for the broadcast! :)

0307z - 6963 USB. Music. SINPO 55344. Peaking ~S9 via Airspy HF+D and 148' loop-on-ground. Moderate static crashing, but otherwise a good copy.
0307z - "WTF Radio Worldwide" ID
0350z - Off air

Thanks for the broadcast! :)

Yeah mine did not save it. Probably because I had to do a two pass flash due to how VirtualBox handles USB device detection.

I am narrowing down my calibration at the moment. WWV frequencies should suffice for HF reception.

I did find that NOAA VHF frequency deviations seem to vary transmitter to transmitter.

I would prefer a good ATSC pilot carrier, but that is proving elusive at the moment due to being in a fringe reception area.

Also I might email to see if the original calibration is on file as well for comparison. Kind of a "whatever" I suppose, as I figure it has drifted by now anyway.

All the above annoyance(s) aside, I probably should obtain a basic GPSDO at some point, too.

Calibration set at 222PPB now. 2500, 5000, and 15000 are so close the calibration might as well be flat. 10000 might be off a few PPB, but a few PPB is not enough to care IMHO.

20000 and 25000 have faded out tonight, but IIRC, around 220-222PPB was what I had at 25000 earlier tonight.

(click to enlarge)

BTW, I just noticed mine might not have restored the factory calibration. I need to check.

There is a hfplus_ppb.exe utility for manually reading and setting the calibration included in the firmware download. You can use SDR# in debug mode to find the calibration valiue.


According to the second link, Airspy.US appears to have oringal calibrations on file if purchased there.

Sure enough mine needs recalibrated. I found the value with SDR# in debug mode, but it would not write for whatever reason (maybe VirtualBox). I was able to set the value with hfplus_ppb.exe included with the firmware tools download. Now to narrow down the calibration number.

Firmware updates are available for the Airspy HF+ series of SDRs.

https://airspy.com/airspy-hf-discovery/ (firmware info near bottom of page)
https://airspy.com/downloads/airspy-hf-flash-2024-03-14_4.0.8.zip (latest firmware as of this post)

Recent changes:

R4.0.0 - 2024-03-10

Updated the ST firmware. Better AGC. Faster tuning. More robust USB streaming. Replaced sample rate 256k => 228k.

R4.0.1 - 2024-03-10

Added fall-back support for legacy systems (out-of-date Linux, old libs, etc.)

R4.0.2 - 2024-03-11

Ported the firmware code from Atmel Studio to Visual Studio 2022 + VisualGDB.
Added more compatibility code for manual gain in the HF band.

R4.0.3 - 2024-03-12

Added initialization code to make the unit usable right after flashing, without a hard reset.

R4.0.4 - 2024-03-13

Added 650 ksps sample rate with Low-IF. Stop the streaming when the USB connection is closed.

R4.0.5 - 2024-03-14

Adjusted the buffering to support slow USB controllers and USB hubs.

R4.0.6 - 2024-03-14

Increased the interrupt frequency for better handling of the AGC.

R4.0.7 - 2024-03-14

Fixed the initialization of the 384k and 192k sample rates.

R4.0.8 - 2024-03-14

Faster HF AGC convergence.

I upgraded my HF+D to firmware R4.0.8 2024-03-14 with Win11 under VirtualBox. The process took some extra steps, but it worked okay for me. YMMV.

Connect to the Airspy HF+ using the VitualBox USB devices menu.

Airspy HF+ Flash Utility
Looking for a suitable flashable device...
No Instance(s) Available.
Looking for a suitable flashing driver...
This one can do the job: \WINDOWS\INF\OEM32.INF
Saving the calibration...
Rebooting the device in flash mode...
No Instance(s) Available.
Press a key to close.

Connect to the Amtel Boot device using the VitualBox USB devices menu. Select your specific HF+ model.

Airspy HF+ Flash Utility
Looking for a suitable flashable device...
Flashable device found on port COM3
Help us decide what to do. Which device are you trying to flash?
1 Airspy HF+ DUAL PORT
Enter a number: 3
Using binary file hfplus-firmware-cd.bin
Unlock all regions
Erase flash

Done in 0.017 seconds
Write 28700 bytes to flash (113 pages)
[==============================] 100% (113/113 pages)
Done in 11.739 seconds
Verify 28700 bytes of flash
[==============================] 100% (113/113 pages)
Verify successful
Done in 8.415 seconds
Set boot flash true
Rebooting the device in normal mode...
The system cannot find the file Calib.
Restoring the calibration...
Press a key to close.

Connect to the Airspy HF+ using the VitualBox USB devices menu. Enjoy.

0241z - Plane and other sound effects. SIO 333. S6 via KiwiSDR 2 and 31' vertical.
0241z - Music. Some band noise, plus my usual nighttime Indy Radio AM carrier on 6931.

Thanks for the broadcast! :)

0237z - OM into music. SIO 333. S6 via KiwiSDR 2 and 31' vertical. Some fading and band noise at the moment, but nonetheless copyable.

Thanks for the broadcast! :)

Stern Radio on 6960.65 AM.

~0135z - "Transmitter is smoking...." into music. SIO 544. Peaking S9+10 via KiwiSDR 2 and 31' vertical. Wide audio. Some fading.
0139z - Stern Radio station ID
0143z - Intermittent digital UTE activity noted
0143z - "Transmitter is smoking...."

Thanks for the broadcast! :)

Music at 0101z. SIO 333. ~S6 via KiwiSDR 2 and 31' vertical. Good bass. Digital UTE activity on frequency noted.

Thanks for the broadcast! :)

ID at 2338z into music. SIO 333. ~S6 via KiwiSDR 2 and 31' vertical. Some UTE or whatever interference underneath at the moment here.

Thanks for the broadcast and shout-out! :)

A thermal compound issue does not surprise me. Many compounds, from cheap to even rather expensive exotics, tend to dry out under heavy cycling and/or high-temp loading. Pump-out is another concern as well.

I often use Shin-Etsu G751 (4.5W/mk), X23-7762 (6.0W/mk), or similar for standard thermal interfaces. Usually better than the cheapest stuff. Tends to hold up for years under normal usage. Shin-Etsu is popular in the OEM computer industry for a reason.

I do use "better" pastes for certain projects. Case in point, and IIRC, I used Thermal Grizzly Hydronaut (11.8W/mk) when last upgrading the processors in my Xeon 96-core / 192-thread server. It is formulated for long-term stability instead of outright thermal conductivity. Seems to be working fine so far.

For a direct comparison from the same brand, Thermal Grizzly Kryonaut (12.5W/mk) is (was?) popular among overclocking enthusiasts. It is also one of those formulas that tends to dry out quicker under heavy thermal loading. It is not worth the potential hassle for that particular system IMO.

SDR - Software Defined Radio / Re: Zeus software
« on: March 10, 2024, 2134 UTC »
The RTL-SDR V4 with its integrated upconverter is much better than the older RTL-SDR V3 in direct sampling mode, so at least you got that going for ya'. :)

The RTL-SDR V4 should suffice for casual HF listening, especially for the flamethrower SWL broadcast stations, area HF amateur nets, etc.

Just do not plan on much serious weak signal reception work. For example the RTL-SDR devices have an 8-bit ADC, so dynamic range is more like 48dB or less. For comparison the dynamic range of an Airspy HF+ Discovery with its 18-bit design (with 16-bit scaling) is more like 110dB. That is before we get into selectivity, sensitivity, image rejection, etc.

For much the same reasons take care regarding overloading and oversaturating your RTL-SDR. Think relatively basic preferable outdoor antennas like maybe a 6'-9' vertical fed against a ground rod, 10m-band horizontal dipole, 45'-60' loop-on-ground, etc. to start.

There are numerous open source and freeware SDR client apps available.

SDR# is popular with the RTL-SDR crowd. You might find the "SDR# Big Book" PDF doc on the same download page helpful.


Other popular SDR clients:


And even more:


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