1
Shortwave Pirate Radio In North America And Around The World, And Other Signals That Go Bump In The Night
We seek to understand and document all radio transmissions, legal and otherwise, as part of the radio listening hobby. We do not encourage any radio operations contrary to regulations.
Always consult with the appropriate authorities if you have questions concerning what is permissible in your locale.
http://ka7oei.blogspot.com/2023/09/
KA7OEI’s conclusions:
“….The best HF weak-signal performance for the RX-888 (Mk2) will occur with the receiver configured for "High" gain mode, 0 dB attenuation and a gain setting of about 20dB. Having said this, you should always to the "antenna versus no antenna" test: If you see more than 6-10dB increase in the noise level at the quietest frequency, you probably have too much gain. Conversely, if you don't see/hear a difference, you probably need more gain - taking care in doing so.
For best HF performance of this - or any other wideband, direct-sampling HF SDR (RX-888, KiwiSDR, Red Pitaya, etc.) additional filtering is suggested - particularly the "shelving" filter described above.
In situations where the noise floor is very low (e.g. a nice, receive quiet location) many direct-sampling SDRs (RX-888, KiwiSDR, Red Pitaya) will likely need additional gain to "hear" the weaker signals - particularly on the higher HF bands. While some of these receivers offer onboard gain adjustment, the use of external high-performance amplification (along with filtering and careful adjustment of the devices' gain adjustments) will give improved absolute sensitivity while helping to preserve large-signal handling capability.
Because the RX-888 is a computer-connected device, there will be ingress of undesired signals from the computer and the '888's built-in circuitry. The use of external amplification - along with appropriate decoupling (e.g. common-mode chokes on the USB cable and connecting coaxial cables) can minimize the appearance of these signals…….”
Some noise sources you might not suspect:
https://youtu.be/ewcemoXLzcU
I use switches like this to turn off noisy items (like my Keurig) when I am not using them:
https://www.amazon.com/Oviitech-Grounded-Outlet-Adapter-Indicator/dp/B0747N2Z66/ref=sr_1_4_sspa?
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2
General Radio Discussion / WWFD stays full-time digital
« on: October 12, 2023, 2143 UTC »
I can occasionally hear WWFD on my truck radio. It sounds surprisingly good for an AM band broadcast station.
https://www.radioworld.com/columns-and-views/from-the-editor/am-digital-wwfd-concludes-its-test-phase
https://www.radioworld.com/columns-and-views/from-the-editor/am-digital-wwfd-concludes-its-test-phase
3
General Radio Discussion / Larry Vanhorn SK
« on: October 12, 2023, 1227 UTC »
Larry Vanhorn, long time Military Comm DXer, writer for Monitoring Times, and author of “The Milcom Files” books passed away in August.
https://forums.radioreference.com/threads/announcement-passing-of-larry-van-horn-n5fpw.464071/
https://forums.radioreference.com/threads/announcement-passing-of-larry-van-horn-n5fpw.464071/
4
General Radio Discussion / DK8OK?
« on: September 26, 2023, 1420 UTC »
What ever happened to DK8OK? For a while there were many papers and articles written by him but lately I haven’t seen anything. His web site (DK8OK.org) seems to have been captured by some bogus entity.
5
SDR - Software Defined Radio / SDR front end filtering and preamps
« on: September 07, 2023, 1240 UTC »http://ka7oei.blogspot.com/2023/09/
KA7OEI’s conclusions:
“….The best HF weak-signal performance for the RX-888 (Mk2) will occur with the receiver configured for "High" gain mode, 0 dB attenuation and a gain setting of about 20dB. Having said this, you should always to the "antenna versus no antenna" test: If you see more than 6-10dB increase in the noise level at the quietest frequency, you probably have too much gain. Conversely, if you don't see/hear a difference, you probably need more gain - taking care in doing so.
For best HF performance of this - or any other wideband, direct-sampling HF SDR (RX-888, KiwiSDR, Red Pitaya, etc.) additional filtering is suggested - particularly the "shelving" filter described above.
In situations where the noise floor is very low (e.g. a nice, receive quiet location) many direct-sampling SDRs (RX-888, KiwiSDR, Red Pitaya) will likely need additional gain to "hear" the weaker signals - particularly on the higher HF bands. While some of these receivers offer onboard gain adjustment, the use of external high-performance amplification (along with filtering and careful adjustment of the devices' gain adjustments) will give improved absolute sensitivity while helping to preserve large-signal handling capability.
Because the RX-888 is a computer-connected device, there will be ingress of undesired signals from the computer and the '888's built-in circuitry. The use of external amplification - along with appropriate decoupling (e.g. common-mode chokes on the USB cable and connecting coaxial cables) can minimize the appearance of these signals…….”
6
General Radio Discussion / HF Traders
« on: August 13, 2023, 1453 UTC »
This epub contains a number of news about applications for FCC STAs. Most of the issues have an article of some sort about HFT stations. It is free, but you do have to provide your email address.
https://www.experimentalradio.news/
https://www.experimentalradio.news/
7
General Radio Discussion / Long Wave STA
« on: August 13, 2023, 1433 UTC »
From Experimental Radio News, issue 8:
(https://www.experimentalradio.news/experimental-radio-news-8/)
Longwave for remote sensing
Lunasonde was issued Special Temporary Authorization WV9XBO for experiments at 119-121 kHz, as it develops an Earth-sensing constellation to detect ground resources.
“Lunasonde’s ability to look 15,000 times deeper than current satellites and sensors is the next frontier in resource exploration," the company said. “Our small satellite can locate groundwater, mineral deposits, and other geological resources up to two kilometers underground. Our data is collected in three minutes and provides a true 3D map of the earth's subsurface."
For the low-frequency STA, “The proposed testing is necessary to increase the technology readiness level of the Lunasonde LF transceiver. A 100-foot structure located in Tucson, AZ will transmit in the requested frequency band.
“During a test mission, one uncrewed high-altitude balloon will carry one LF receiver system approximately 60,000-100,000 feet above ground level over the transmission structure. Transmitted signals that reflect from the Earth’s surface would be received by the free-floating balloon receiver system. ...
“The system is equipped with a redundant cut-down device, a radar reflector, and an ADS-B transponder… The balloon is returned to the ground either when it reaches maximum altitude (approximately 100,000-130,000 ft) or when the cutdown is commanded, at which point a parachute is used to safely return the payload to the ground. In either scenario, Lunasonde will retrieve the balloon and equipment.”
‘No expectations’ for future approval
“Lunasonde, Inc. shall have no expectations that future requests for operational use of this transceiver from low earth orbit using the 119-121 kHz band will be approved, and Lunasonde, Inc. should ensure that any future operational use of this equipment be conducted in appropriately allocated frequency bands,” the FCC told the company.
(https://www.experimentalradio.news/experimental-radio-news-8/)
Longwave for remote sensing
Lunasonde was issued Special Temporary Authorization WV9XBO for experiments at 119-121 kHz, as it develops an Earth-sensing constellation to detect ground resources.
“Lunasonde’s ability to look 15,000 times deeper than current satellites and sensors is the next frontier in resource exploration," the company said. “Our small satellite can locate groundwater, mineral deposits, and other geological resources up to two kilometers underground. Our data is collected in three minutes and provides a true 3D map of the earth's subsurface."
For the low-frequency STA, “The proposed testing is necessary to increase the technology readiness level of the Lunasonde LF transceiver. A 100-foot structure located in Tucson, AZ will transmit in the requested frequency band.
“During a test mission, one uncrewed high-altitude balloon will carry one LF receiver system approximately 60,000-100,000 feet above ground level over the transmission structure. Transmitted signals that reflect from the Earth’s surface would be received by the free-floating balloon receiver system. ...
“The system is equipped with a redundant cut-down device, a radar reflector, and an ADS-B transponder… The balloon is returned to the ground either when it reaches maximum altitude (approximately 100,000-130,000 ft) or when the cutdown is commanded, at which point a parachute is used to safely return the payload to the ground. In either scenario, Lunasonde will retrieve the balloon and equipment.”
‘No expectations’ for future approval
“Lunasonde, Inc. shall have no expectations that future requests for operational use of this transceiver from low earth orbit using the 119-121 kHz band will be approved, and Lunasonde, Inc. should ensure that any future operational use of this equipment be conducted in appropriately allocated frequency bands,” the FCC told the company.
8
The RF Workbench / All Electronics going out of business
« on: June 19, 2023, 1238 UTC »
All Electronics, a vendor of electronic parts, is closing in August. They were a source of some hard to find electronic parts (like old school high voltage mica transmitting capacitors).
www.allelectronics.com
www.allelectronics.com
9
The RF Workbench / Ferrites and Inductors for EMI Control
« on: June 01, 2023, 1732 UTC »
This is a good basic article on choosing ferrites and inductors for EM noise suppression. It discusses choices, best practices, and why your filters may be ineffective.
https://digital.incompliancemag.com/issue/june-2023/inductors-and-ferrites-for-use-in-emc/
https://digital.incompliancemag.com/issue/june-2023/inductors-and-ferrites-for-use-in-emc/
10
Equipment / State of HF transceiver art
« on: May 25, 2023, 1120 UTC »
This is from the 2023 CTU, and discusses the performance of current HF transceiver offerings. Most of the discussion is on receiver performance.
Note that it says 60,000 Icom IC7300 radios have been sold. This is surely the most popular HF radio ever. I have heard anecdotal stories of SWL’s buying them just to use as a receiver.
https://www.contestuniversity.com/wp-content/uploads/2023/05/Transceiver-Performance-Selection-of-a-Radio-2023.pdf
Note that it says 60,000 Icom IC7300 radios have been sold. This is surely the most popular HF radio ever. I have heard anecdotal stories of SWL’s buying them just to use as a receiver.
https://www.contestuniversity.com/wp-content/uploads/2023/05/Transceiver-Performance-Selection-of-a-Radio-2023.pdf
11
SDR - Software Defined Radio / SDRPlay SDR Receiver problem
« on: May 23, 2023, 1127 UTC »
This article identifies the possibility of undesired signals when using SDRPlay receivers.
While the article focuses on SDRPlay, the problem might exist on other brands. If this turns out to be a problem for you, the fix is to use an outboard filter.
http://ka7oei.blogspot.com/2023/05/
One possible source of low cost bandpass filters is here:
http://www.qrp-labs.com/bpfkit.html
and low pass filters here:
http://www.qrp-labs.com/lpfkit.html
While the article focuses on SDRPlay, the problem might exist on other brands. If this turns out to be a problem for you, the fix is to use an outboard filter.
http://ka7oei.blogspot.com/2023/05/
One possible source of low cost bandpass filters is here:
http://www.qrp-labs.com/bpfkit.html
and low pass filters here:
http://www.qrp-labs.com/lpfkit.html
12
SDR - Software Defined Radio / RX-888
« on: May 15, 2023, 1330 UTC »
I don’t know how recent this is. Phil Karn KA9Q is developing a multi channel program to work with the RX-888 receiver. He calls it KA9Q-Radio. I don’t see a date on the sdrutah page. The youtube link looks to be a month old.
I don’t know how recent this is. Phil Karn KA9Q is developing a multi channel program to work with the RX-888 receiver. He calls it KA9Q-Radio. I don’t see a date on the sdrutah page. The youtube link looks to be a month old.
http://www.sdrutah.org/info/using_ka9q_radio_with_the_rx888.html
https://github.com/ka9q/ka9q-radio
This Youtube video has Phil talking about it.
https://youtu.be/7nhBFSGby2o
edit:
KA9Q-Radio is actually designed to work with multiple radios, like the RTL-SDR and the AirSpy. The neat thing about it is the ability to simultaneously decode multiple channels. A radio that could capture the entire HF spectrum, like the RX-888 might have, would allow the ability to capture all HF at once. In the video Phil shows how he has been capturing every 2M, 440, and 220 repeater in his location all at once, using 3 Raspberry Pi computers, and saving to disk. He said he had 2 years of data, occupying about 2 TB.
Phil says his code is relatively stable now and he is looking for other programmers to develop better end user interfaces.
I don’t know how recent this is. Phil Karn KA9Q is developing a multi channel program to work with the RX-888 receiver. He calls it KA9Q-Radio. I don’t see a date on the sdrutah page. The youtube link looks to be a month old.
http://www.sdrutah.org/info/using_ka9q_radio_with_the_rx888.html
https://github.com/ka9q/ka9q-radio
This Youtube video has Phil talking about it.
https://youtu.be/7nhBFSGby2o
edit:
KA9Q-Radio is actually designed to work with multiple radios, like the RTL-SDR and the AirSpy. The neat thing about it is the ability to simultaneously decode multiple channels. A radio that could capture the entire HF spectrum, like the RX-888 might have, would allow the ability to capture all HF at once. In the video Phil shows how he has been capturing every 2M, 440, and 220 repeater in his location all at once, using 3 Raspberry Pi computers, and saving to disk. He said he had 2 years of data, occupying about 2 TB.
Phil says his code is relatively stable now and he is looking for other programmers to develop better end user interfaces.
13
Equipment / Wellbrook Antennas closing
« on: March 24, 2023, 1526 UTC »
Wellbrook antennas is closing at the end of April. The owner is retiring.
https://www.wellbrook.uk.com/loopantennas/
https://www.wellbrook.uk.com/loopantennas/
14
General Radio Discussion / Russian Comms
« on: March 12, 2022, 1858 UTC »
From the Scan-DC mailing list:
https://rusi.org/explore-our-research/publications/commentary/russian-comms-ukraine-world-hertz
I have seen Reddit postings of supposed sound bites of Russian troops calling home where they talk of looting and murders. If Ukraine is the source of those postings, then they must be actively mining the cellular network. If the Russians are using cellphones for Command and Control like the URL article suggests, then the Ukrainians are reading this too.
https://rusi.org/explore-our-research/publications/commentary/russian-comms-ukraine-world-hertz
I have seen Reddit postings of supposed sound bites of Russian troops calling home where they talk of looting and murders. If Ukraine is the source of those postings, then they must be actively mining the cellular network. If the Russians are using cellphones for Command and Control like the URL article suggests, then the Ukrainians are reading this too.
15
Equipment / Noise around the house
« on: March 04, 2022, 1251 UTC »Some noise sources you might not suspect:
https://youtu.be/ewcemoXLzcU
I use switches like this to turn off noisy items (like my Keurig) when I am not using them:
https://www.amazon.com/Oviitech-Grounded-Outlet-Adapter-Indicator/dp/B0747N2Z66/ref=sr_1_4_sspa?