KFS omni kiwi sdr "Masking" USAF global HF Frequency??

[Teotwaki]

Tried tuning in 11,175 KHz yesterday and I could see activity on the waterfall but no audio. Then I noticed this tag


So what sort of feature is this on the SDR and what is it normally used for? It was not applied to other global HF frequencies.

Thanks!

[ChrisSmolinski]

KiwiSDR owners can mask or block certain frequencies or bands, so they cannot be listened to.

Usually this is done in response to abusive users, who will sit on a particular frequency for hours on end, tying up the receiver and preventing others from using it.

I've had to do it on a few frequencies, myself.

[Teotwaki]

Thanks! That makes perfect sense. I had not thought about what the owner of a public SDR has to go through with abusers. I try to get in and out of SDRs as quickly as possible.

[ChrisSmolinski]

I certainly don't mind if someone sits on a frequency for an extended period while they are actively listening - that's what the KiwiSDRs are for.  But sometimes you have to wonder...

The worst case I've had here is someone from Taiwan who would connect to all 7 of the KiwiSDRs here at the same time, and sit on a CHU frequency for 12+ hours. 

[Charlie_Dont_Surf]

The worst case I've had here is someone from Taiwan who would connect to all 7 of the KiwiSDRs here at the same time, and sit on a CHU frequency for 12+ hours.

I'm sure it was some long term propagation studies with multiple antennas. The timestamps are built in.   Or he reeeally wanted to be very, very, very sure that he had the time in English and French every minute.

I've seen this on some Russian KiwiSDRs too, where they have blocked reception of The Buzzer or the like. Example: http://msk.swl.su:8074/?f=4625usbz6

[Teotwaki]

I've seen this on some Russian KiwiSDRs too, where they have blocked reception of The Buzzer or the like. Example: http://msk.swl.su:8074/?f=4625usbz6

That's a neat example

[cyphermatic]

LOL, just don't block Brother Stair.  Actually, I have noticed certain Russian KiwiSDR sites with dozens and dozens of masked frequencies. The only sense I could make of those is that they're manipulating SNR calculations.

As to 11175 being blocked, well... there's still 8992 and a few others.  There are better locations to listen from for the HFGCS / Nightwatch net. Try northern California, Idaho, Montana, and southern Alberta for nice reception -- and around Cape Cod in the eastern states. With good propagation, you can receive the white noise from the phone lines / satellite links to those ground stations.

[Josh]

LOL, just don't block Brother Stair.  Actually, I have noticed certain Russian KiwiSDR sites with dozens and dozens of masked frequencies. The only sense I could make of those is that they're manipulating SNR calculations.

As to 11175 being blocked, well... there's still 8992 and a few others.  There are better locations to listen from for the HFGCS / Nightwatch net. Try northern California, Idaho, Montana, and southern Alberta for nice reception -- and around Cape Cod in the eastern states. With good propagation, you can receive the white noise from the phone lines / satellite links to those ground stations.

What's amazing to me is russia allows kiwis in the first place, considering their soviet past. Never in a million years thought I'd see the day when anyone in the world can tune in to a sdr located in russia or warsaw pact country. Back in the day we had to ring them ruskiis with listening posts and pray for good conditions, now an hf rx in moscow be tuned by any browser anywhere on earth.

[Charlie_Dont_Surf]

What's amazing to me is russia allows kiwis in the first place, considering their soviet past. Never in a million years thought I'd see the day when anyone in the world can tune in to a sdr located in russia or warsaw pact country. Back in the day we had to ring them ruskiis with listening posts and pray for good conditions, now an hf rx in moscow be tuned by any browser anywhere on earth.

I hear you. I wondered if the Russians and the Chinese block SDR feeds from receivers outside their borders but then I would see a lot of users with IP addresses in Russia and China using Kiwis.

I always thought this was surprising given that the Chinese block Facebook, for example. On the other hand, SW radio isn't a mass medium anymore.

[ChrisSmolinski]

I hear you. I wondered if the Russians and the Chinese block SDR feeds from receivers outside their borders but then I would see a lot of users with IP addresses in Russia and China using Kiwis.

I always thought this was surprising given that the Chinese block Facebook, for example. On the other hand, SW radio isn't a mass medium anymore.

I do often see Chinese IP addresses on the KiwiSDRs here, sometimes sitting on frequencies for hours. Often monitoring .mil stuff which makes me suspect they are government users and not DXers. I've tried banning them, but it's like whack-a-mole.

[~SIGINT~]

The blocking of IPs is best handled with a featured call "geoip blocking" based on the GeoIP database. Many commercial firewalls now include this feature, sometimes at a cost. There are free alternatives available. It has been several years now since I have worked with this but there were community editions of, for example, pfSense and Sophos UTM just to name a couple, that are widely popular. Obviously, this is best managed at the network edge but there are also independent Linux packages available which may allow the possibility of implementing the geoip blocking feature directly in the Kiwi's OS.

Here are a couple of links for reference:

Need a cheap firewall that can geo-block IP's outside of USA

Block IP range from countries with GeoIP and iptables

[cyphermatic]

The People's Republic of (and not Taiwan - just "the Republic of") China is a funny place. They jam the hell out of a lot of shortwave broadcasts and block streams from Western media, but they don't block many SDRs. There is a site where you can test urls to see what they block, and the PRC doesn't care about many of those SDRs. Perhaps the party is run be a lot of boomers who don't understand the tech.

Oddly, there are people operating internet SDRs from within the PRC. I noticed that chat boxes are absent, as there is some sort of rule requiring moderation anywhere people talk to other people. But the SDRs are there and you can listen around. LOL the Firedrake Jammer isn't blocked.

[Pigmeat]

The "Boomers" there died in large numbers in the chaos of the Cultural Revolution of the 60's. The Great Helmsman, Mao, was a sterling leader, he'd lead you right to your grave, but you got spiffy outfit and cap along with a "Little Red Book" for participating.

[ZL/KF6VO]

The only sense I could make of those is that they're manipulating SNR calculations.

After a while we realized this was a bug. So the masked areas are now excluded from the SNR calculation.

Regards,
John, ZL/KF6VO
KiwiSDR

[Charlie_Dont_Surf]

The only sense I could make of those is that they're manipulating SNR calculations.

After a while we realized this was a bug. So the masked areas are now excluded from the SNR calculation.

Regards,
John, ZL/KF6VO
KiwiSDR

Pardon the stupid question but before you excluded the masked areas form the SNR calculation, were they showing as SNR = 0 dB (which is my first thought) or are they showing as SNR = "huge dB", because the signal level is still available to the SNR calculation (despite the mask) and the noise in the masked area is basically zero?