Date   

Re: Question on Antenna design - will mismatch alone change antenna radiation pattern ?

Glenn Elmore
 

Not claiming to be an expert but I would say that pattern is due to response in the far field.  As long as the 'matching' or other radiating mechanisms don't  have significant radiation compared to the 'antenna' then that response won't change.

Having said that, the *apparent* pattern can change. If mismatch gets high enough that other mechanisms, not intended to be included in what one calls the 'antenna', become significant compared to the desired/intended one then the pattern and performance can indeed change be different. 

This second situation is essentially what happens with common mode ingress. That which one *thinks* is the antenna is not really the total of what is providing response at the receiver.  Once intended antenna (mismatched) signals get down to the level of other signals, such as CM then the effective pattern is no longer entirely due to the intended antenna.

This problem can be aggravated by electrically small antennas which though they intercept the same aperture and, were they matched, would deliver the same signal power, deliver very small voltage or current levels due to their preamplifiers because of the low radiation resistance and high reactance and imperfect matching.

Perhaps surprisingly, were we able to perfectly match a [1 cm] dipole at 160m it would have just about the same performance as a full half wave. Of course we can't do that with materials we have, probably not even with super conductors so in practice this doesn't occur. 

But the general idea of using "something" as an antenna, no matter whether the feedpoint impedance is near something easy to access with reasonable matching materials, is perfectly fine as long as one compares the resulting mismatch to the target at a particular frequency of interest.  That target starts to get difficult at the high end of HF where we want to get increasingly close (or below) KTB. It's for this reason that either a loop, such as described by LZ1AQ, or my dipoles both fail to achieve the ITU 'quiet rural' noise floor at 10m.  More or less, it takes larger structures to get something that has a chance of 'not too bad' match over broader frequency range with a finite number of real components.


Question on Antenna design - will mismatch alone change antenna radiation pattern ?

ON5KQ
 

I have a fundamental question - may be Glenn or other experts can answer:

I have a nice antenna in mind to build up for reception only (Wsprdaemon)
However this design is only well matched at a single band. Neglecting any radiating feedline or common-mode effects, the NEC2 model tells me however, that even with high mismatch  on other bands the radiation pattern would be different but also very beneficial.

Now for the practical construction, I wonder:
- if I would put a buffer pre-amplifier directly at the feedpoint (where the source in the NEC2 model is) and therefore do not introduce a feedline at all between antenna and pre-amp, would the radiation pattern will be any different than what the NEC2 models tells me, because of the heavy mismatch between the antenna impedance and the input impedance of the amplifier ? Would it require any special pre-amp to keep the radiation pattern unchanged to the NEC2 model ?

From theory I would say that there is no change in radiation pattern, rather than most likely a heavy drop in antenna efficiency (losses)... however from practical builds, my experience is completely different! Heavily mismatched antennas never really worked, even with a pre-amp...
(The design is for the high bands 10Mhz and higher)

As it would be some significant work to build it up - what do you think..?
Just go for it, even though it is a single band design and even though Wsprdaemon requires broadband performance ?
(but for reception with active feed)

What do I need to pay attention for, if I want to feed it with a pre-amp for wideband use, although the wire construction shows a narrowband characteristic at 75Ohm feedline (RG6)

Ulli, ON5KQ


Re: Has anyone run auto-wspr and/or WD on a RaspSDR?

VE3VXO
 

I am about to embark on this adventure myself but waiting for my hardware to arrive and am pretty clueless about linux although I did install ubuntu on a machine once  and did a few command line things (following instructions I found online) but if there are those who set this up and got it working I could certainly benefit from a few pointers when the time comes.

Browsing the messages on this list I realise I am pretty much in the deep end of the pool here....



---------- Original Message ----------
From: Rob Robinett <rob@...>
Date: July 17, 2021 at 7:02 PM

I forget who it was who reported that loading a new version of the kiwi code got their RaspberryPi working in autowspr and with WD.

In the conf file you should need only to define the KIWI receiver as on localhost, e.g.:

declare RECEIVER_LIST=(
         "KIWI_0                    localhost:8073     AI6VN         CM87tj    NULL"
)

then define a schedule like:

declare WSPR_SCHEDULE=(
   "00:00 KIWI_0,80 KIWI_0,40 KIWI_0,30 KIWI_0,20 KIWI_0,17 KIWI_0,15 KIWI_0,12 KIWI_0,10"
)


 


Re: Backdoor in KiwiSDR

KD2OM
 

Mine aren’t publicly listed but are available. I rarely see anyone else on it and I checked for incursion and found none. Plus I already had external admin console access closed. 
That said I did the update.

Steve KD2OM

.
 

On Jul 17, 2021, at 18:09, kk6pr <pointreyes@...> wrote:


" . . .Chinese IPs logged onto my KiwiSDR to monitor US military frequencies . . . The thought of the Chinese Communist Party adding and exploiting another backdoor entrance into my KiwiSDR is unsettling."

I'm more concerned about American fascists' access and use of my Kiwis.  My IP Blacklist is full of them - I don't care what frequencies they want to listen to.

On Sat, Jul 17, 2021 at 12:58 PM Carol KP4MD <kp4md@...> wrote:
I have no problem with John Seamons having access, but I was spooked and removed my KiwiSDR from the public Kiwi directory and DDNS service once I detected Chinese IPs pinging my router with port scanning attacks and several Chinese IPs logged onto my KiwiSDR to monitor US military frequencies.  The thought of the Chinese Communist Party adding and exploiting another backdoor entrance into my KiwiSDR is unsettling.


Re: Has anyone run auto-wspr and/or WD on a RaspSDR?

Rob Robinett
 
Edited

I forget who it was who reported that loading a new version of the kiwi code got their RaspberryPi working in autowspr and with WD.
Once autowspr works, disable it so WD can use those rx channels.

In the conf file you should need only to define the KIWI receiver as on localhost, e.g.:

declare RECEIVER_LIST=(
         "KIWI_0                    localhost:8073     AI6VN         CM87tj    NULL"
)

then define a schedule like:

declare WSPR_SCHEDULE=(
   "00:00 KIWI_0,80 KIWI_0,40 KIWI_0,30 KIWI_0,20 KIWI_0,17 KIWI_0,15 KIWI_0,12 KIWI_0,10"
)


Re: Has anyone run auto-wspr and/or WD on a RaspSDR?

Roland
 

Has this been resolved? Can somebody share the wsprdaemon.conf file for the RaspSDR?


Re: Backdoor in KiwiSDR

kk6pr
 

" . . .Chinese IPs logged onto my KiwiSDR to monitor US military frequencies . . . The thought of the Chinese Communist Party adding and exploiting another backdoor entrance into my KiwiSDR is unsettling."

I'm more concerned about American fascists' access and use of my Kiwis.  My IP Blacklist is full of them - I don't care what frequencies they want to listen to.


On Sat, Jul 17, 2021 at 12:58 PM Carol KP4MD <kp4md@...> wrote:
I have no problem with John Seamons having access, but I was spooked and removed my KiwiSDR from the public Kiwi directory and DDNS service once I detected Chinese IPs pinging my router with port scanning attacks and several Chinese IPs logged onto my KiwiSDR to monitor US military frequencies.  The thought of the Chinese Communist Party adding and exploiting another backdoor entrance into my KiwiSDR is unsettling.


Re: Backdoor in KiwiSDR

Carol KP4MD
 

I have no problem with John Seamons having access, but I was spooked and removed my KiwiSDR from the public Kiwi directory and DDNS service once I detected Chinese IPs pinging my router with port scanning attacks and several Chinese IPs logged onto my KiwiSDR to monitor US military frequencies.  The thought of the Chinese Communist Party adding and exploiting another backdoor entrance into my KiwiSDR is unsettling.


Re: Backdoor in KiwiSDR

Jim Lill
 

I agree and let's hope that John will continue to help us even if it means one on one access.  My recent ALE experiment was only possible becaus eJohn had that access to one of my Kiwi's for example

On 7/17/21 10:03 AM, Rob Robinett wrote:
I share Glenn and Stu's perspective on this issue.
Over the years John has demonstrated that he deserves our trust and appreciation for all of his work.
Hopefully all of this negative publicity doesn't drive him away from further work on the Kiwi.

On Fri, Jul 16, 2021 at 10:41 PM Stu C <stu@...> wrote:
As I understand it the access was permitted from only one IP address so
unless the miscreant managed to get hold of that base then launch
attacks the risk is small.
I too trust John and have made an SDR available to him via SSH many
times without a moments hesitation. One thing a generation focussed on
"correct" pronouns forgets is the morals and ethics of the older
generation bare little resemblance to (many) of those today. People who
lived most of their lives before the internet would generally not have
stolen music or avoided paying for goods (like software).

I had a Chinese NVR that I had somehow forgotten the password to,
support did not have a way for me to personally reset it at the hardware
but if I just gave it internet access they would do it for me in
minute... yeah no thanks. Half the complication of my home network
subnets, NAT and firewall is aimed at using off the shelf CCTV bits
without inviting a complete take over of my home network or being base
for further attacks. It is probably illegal to export an item from
country X without enabling a gov backdoor.

The fact that so many KiwiSDR's are still online makes me think that
most users understand this event and have decided the intention was good
if the inclusion does not suit today's world.

Has made me view the reporting of these events slightly differently,
drama sells, click bait etc.

Stu



On 17/07/2021 06:10, Glenn Elmore wrote:
>
>
> That John has had root access to KiwiSDRs has not been a secret for
> many years. To even a casual reader of the forum this has been
> obvious. Personally I have been aware of this and felt John was
> trustworthy and him having root access to a host on my private network
> and being able to help with troubleshooting had acceptable
> risk/benefit ratio.
>
> What seems new is simply the high level publicity of this fact.
> Perhaps I'm being naive but the only new risk I see here is that the
> announcement may trigger increased hacking attempts. Hopefully the
> changes in v .461 have/will mitigate these risks.
>
> Does anyone know of an instance where this 'vulnerability' has been
> exploited? Am I being silly with this perspective?
>
> Glenn n6gn
>
>
> On 2021-07-16 13:55, Carol KP4MD wrote:
>
>> "On Wednesday, users learned that for years, their devices had been
>> equipped with a backdoor that allowed the KiwiSDR creator—and
>> possibly others—to log in to the devices with administrative system
>> rights. The remote admin could then make configuration changes and
>> access data not just for the KiwiSDR but in many cases to the
>> Raspberry Pi <https://arstechnica.com/tag/raspberry-pi/>, BeagleBone
>> Black, or other computing devices the SDR hardware is connected to."
>>
>> The full story is at
>> https://arstechnica.com/gadgets/2021/07/for-years-a-backdoor-in-popular-kiwisdr-product-gave-root-to-project-developer/
>> <https://arstechnica.com/gadgets/2021/07/for-years-a-backdoor-in-popular-kiwisdr-product-gave-root-to-project-developer/>
>
>









--
Rob Robinett
AI6VN
mobile: +1 650 218 8896


Re: Backdoor in KiwiSDR

Rob Robinett
 

I share Glenn and Stu's perspective on this issue.
Over the years John has demonstrated that he deserves our trust and appreciation for all of his work.
Hopefully all of this negative publicity doesn't drive him away from further work on the Kiwi.

On Fri, Jul 16, 2021 at 10:41 PM Stu C <stu@...> wrote:
As I understand it the access was permitted from only one IP address so
unless the miscreant managed to get hold of that base then launch
attacks the risk is small.
I too trust John and have made an SDR available to him via SSH many
times without a moments hesitation. One thing a generation focussed on
"correct" pronouns forgets is the morals and ethics of the older
generation bare little resemblance to (many) of those today. People who
lived most of their lives before the internet would generally not have
stolen music or avoided paying for goods (like software).

I had a Chinese NVR that I had somehow forgotten the password to,
support did not have a way for me to personally reset it at the hardware
but if I just gave it internet access they would do it for me in
minute... yeah no thanks. Half the complication of my home network
subnets, NAT and firewall is aimed at using off the shelf CCTV bits
without inviting a complete take over of my home network or being base
for further attacks. It is probably illegal to export an item from
country X without enabling a gov backdoor.

The fact that so many KiwiSDR's are still online makes me think that
most users understand this event and have decided the intention was good
if the inclusion does not suit today's world.

Has made me view the reporting of these events slightly differently,
drama sells, click bait etc.

Stu



On 17/07/2021 06:10, Glenn Elmore wrote:
>
>
> That John has had root access to KiwiSDRs has not been a secret for
> many years. To even a casual reader of the forum this has been
> obvious. Personally I have been aware of this and felt John was
> trustworthy and him having root access to a host on my private network
> and being able to help with troubleshooting had acceptable
> risk/benefit ratio.
>
> What seems new is simply the high level publicity of this fact.
> Perhaps I'm being naive but the only new risk I see here is that the
> announcement may trigger increased hacking attempts. Hopefully the
> changes in v .461 have/will mitigate these risks.
>
> Does anyone know of an instance where this 'vulnerability' has been
> exploited? Am I being silly with this perspective?
>
> Glenn n6gn
>
>
> On 2021-07-16 13:55, Carol KP4MD wrote:
>
>> "On Wednesday, users learned that for years, their devices had been
>> equipped with a backdoor that allowed the KiwiSDR creator—and
>> possibly others—to log in to the devices with administrative system
>> rights. The remote admin could then make configuration changes and
>> access data not just for the KiwiSDR but in many cases to the
>> Raspberry Pi <https://arstechnica.com/tag/raspberry-pi/>, BeagleBone
>> Black, or other computing devices the SDR hardware is connected to."
>>
>> The full story is at
>> https://arstechnica.com/gadgets/2021/07/for-years-a-backdoor-in-popular-kiwisdr-product-gave-root-to-project-developer/
>> <https://arstechnica.com/gadgets/2021/07/for-years-a-backdoor-in-popular-kiwisdr-product-gave-root-to-project-developer/>
>
>









--
Rob Robinett
AI6VN
mobile: +1 650 218 8896


Re: Backdoor in KiwiSDR

Stu C
 

As I understand it the access was permitted from only one IP address so unless the miscreant managed to get hold of that base then launch attacks the risk is small.
I too trust John and have made an SDR available to him via SSH many times without a moments hesitation. One thing a generation focussed on "correct" pronouns forgets is the morals and ethics of the older generation bare little resemblance to (many) of those today. People who lived most of their lives before the internet would generally not have stolen music or avoided paying for goods (like software).

I had a Chinese NVR that I had somehow forgotten the password to, support did not have a way for me to personally reset it at the hardware but if I just gave it internet access they would do it for me in minute... yeah no thanks. Half the complication of my home network subnets, NAT and firewall is aimed at using off the shelf CCTV bits without inviting a complete take over of my home network or being base for further attacks. It is probably illegal to export an item from country X without enabling a gov backdoor.

The fact that so many KiwiSDR's are still online makes me think that most users understand this event and have decided the intention was good if the inclusion does not suit today's world.

Has made me view the reporting of these events slightly differently, drama sells, click bait etc.

Stu

On 17/07/2021 06:10, Glenn Elmore wrote:


That John has had root access to KiwiSDRs has not been a secret for many years. To even a casual reader of the forum this has been obvious. Personally I have been aware of this and felt John was trustworthy and him having root access to a host on my private network and being able to help with troubleshooting had acceptable risk/benefit ratio.

What seems new is simply the high level publicity of this fact. Perhaps I'm being naive but the only new risk I see here is that the announcement may trigger increased hacking attempts. Hopefully the changes in v .461 have/will mitigate these risks.

Does anyone know of an instance where this 'vulnerability' has been exploited? Am I being silly with this perspective?

Glenn n6gn


On 2021-07-16 13:55, Carol KP4MD wrote:

"On Wednesday, users learned that for years, their devices had been equipped with a backdoor that allowed the KiwiSDR creator—and possibly others—to log in to the devices with administrative system rights. The remote admin could then make configuration changes and access data not just for the KiwiSDR but in many cases to the Raspberry Pi <https://arstechnica.com/tag/raspberry-pi/>, BeagleBone Black, or other computing devices the SDR hardware is connected to."

The full story is at https://arstechnica.com/gadgets/2021/07/for-years-a-backdoor-in-popular-kiwisdr-product-gave-root-to-project-developer/ <https://arstechnica.com/gadgets/2021/07/for-years-a-backdoor-in-popular-kiwisdr-product-gave-root-to-project-developer/>


Re: Backdoor in KiwiSDR

Glenn Elmore
 


 

That John has had root access to KiwiSDRs has not been a secret for many years. To even a casual reader of the forum this has been obvious. Personally I have been aware of this and felt John was trustworthy and him having root access to a host on my private network and being able to help with troubleshooting had acceptable risk/benefit ratio.  

What seems new is simply the high level publicity of this fact. Perhaps I'm being naive but the only new risk I see here is that the announcement may trigger increased hacking attempts.  Hopefully the changes in v .461 have/will mitigate these risks.  

Does anyone know of an instance where this 'vulnerability' has been exploited? Am I being silly with this perspective?

Glenn n6gn


On 2021-07-16 13:55, Carol KP4MD wrote:

"On Wednesday, users learned that for years, their devices had been equipped with a backdoor that allowed the KiwiSDR creator—and possibly others—to log in to the devices with administrative system rights. The remote admin could then make configuration changes and access data not just for the KiwiSDR but in many cases to the Raspberry Pi, BeagleBone Black, or other computing devices the SDR hardware is connected to." 

The full story is at https://arstechnica.com/gadgets/2021/07/for-years-a-backdoor-in-popular-kiwisdr-product-gave-root-to-project-developer/


Backdoor in KiwiSDR

Carol KP4MD
 

"On Wednesday, users learned that for years, their devices had been equipped with a backdoor that allowed the KiwiSDR creator—and possibly others—to log in to the devices with administrative system rights. The remote admin could then make configuration changes and access data not just for the KiwiSDR but in many cases to the Raspberry Pi, BeagleBone Black, or other computing devices the SDR hardware is connected to." 

The full story is at https://arstechnica.com/gadgets/2021/07/for-years-a-backdoor-in-popular-kiwisdr-product-gave-root-to-project-developer/


Re: WSPRdaemon and KiwiSDR Channels

Mike Donnachie
 

Thanks for the prompt reply Rob, I did that and it solved the problem straightaway.

Thanks again !

Mike MM0EFJ



On Thu, Jul 15, 2021 at 9:04 PM Rob Robinett <rob@...> wrote:
On the Kiwi's Admin->Control page change the 'Number of simultaneous channels available for connection by non-Kiwi apps' setting to 8.
The Kiwi will first assign wsprdeamon rx sessions to currently free audio-only channels so that if there are free channels for regular listeners the will be the waterfall channels


Re: WSPRdaemon and KiwiSDR Channels

Rob Robinett
 

On the Kiwi's Admin->Control page change the 'Number of simultaneous channels available for connection by non-Kiwi apps' setting to 8.
The Kiwi will first assign wsprdeamon rx sessions to currently free audio-only channels so that if there are free channels for regular listeners the will be the waterfall channels


WSPRdaemon and KiwiSDR Channels

Mike Donnachie
 

I have set up my Kiwi SDR for 8 channels.
I have set the config file on WSPRDaemon for up to 6 channels.
However WSPRDaemon is only telling the Kiwi to do 4 channels.
I wonder what I have configured incorrectly, the Kiwi or WSPRDaemon ?


Re: New to the list

VE3VXO
 

Hell of an antique!  I still use mine daily as a band monitor and for casual SWL. It's just so convenient!

---------- Original Message ----------
From: Rob Robinett <rob@...>
Date: July 15, 2021 at 2:38 PM

Hi Joe,

You could join our Wednesday 16:00 UTC Zoom call and ask Ulli and others who have extensive experience with the LOG.

You don't need to apologize for trying the RaspberrySDR. Both the KiwiSDR board and the BBG as host are getting to be almost antiques, so I too invested in a close because it covers 6M.

I hope John Seamons soon wants to refresh the Kiwi HW!

Rob


Re: New to the list

Rob Robinett
 

Hi Joe,

You could join our Wednesday 16:00 UTC Zoom call and ask Ulli and others who have extensive experience with the LOG.

You don't need to apologize for trying the RaspberrySDR.  Both the KiwiSDR board and the BBG as host are getting to be almost antiques, so I too invested in a close because it covers 6M.

I hope John Seamons soon wants to refresh the Kiwi HW!

Rob


On Thu, Jul 15, 2021 at 10:49 AM VE3VXO <ve3vxo@...> wrote:
That's interesting.  I tried modelling several different variations but for the phased pair I found that deviating from the corner driven diamond shape resulted in degredation to the pattern either in the RDF or degrading the low elevation response.

Before this thread is done I just wanted to rspond to you Glenn on your good points about supporting the original design and the ongoing development which I do take seriously.  Please remember I do already have a genuine KiwiSDR bought through Seed Studio so I have given financial support to the designer already.  It was hard to get at the time and for us canucks with worthless currency the price differential is substantial so that might be a deciding factor for some folks.  For me right now, as you now understand I'm trying to go for something very specific leveraging the ability to run more code on the cpu and avoid ground loops for one and also have something simple and compact that is easy to deploy in a remote location with no internet while logging spots to a file for later upload, and the original kiwiSDR won't do latent uploads although I did request this as a feature for consideration twice on the valentfx forum in the time since I've owned one and there was no response to it whatsoever.  If my original KiwiSDR could simply run as a reporter without web connectivity and upload when the web is available I wouldn't be considering any other option at all. So it looks like this newer design might be the better choice for me in this particular instance. I hope so, time will tell.

Joe



--
Rob Robinett
AI6VN
mobile: +1 650 218 8896


Re: New to the list

VE3VXO
 

That's interesting.  I tried modelling several different variations but for the phased pair I found that deviating from the corner driven diamond shape resulted in degredation to the pattern either in the RDF or degrading the low elevation response.

Before this thread is done I just wanted to rspond to you Glenn on your good points about supporting the original design and the ongoing development which I do take seriously.  Please remember I do already have a genuine KiwiSDR bought through Seed Studio so I have given financial support to the designer already.  It was hard to get at the time and for us canucks with worthless currency the price differential is substantial so that might be a deciding factor for some folks.  For me right now, as you now understand I'm trying to go for something very specific leveraging the ability to run more code on the cpu and avoid ground loops for one and also have something simple and compact that is easy to deploy in a remote location with no internet while logging spots to a file for later upload, and the original kiwiSDR won't do latent uploads although I did request this as a feature for consideration twice on the valentfx forum in the time since I've owned one and there was no response to it whatsoever.  If my original KiwiSDR could simply run as a reporter without web connectivity and upload when the web is available I wouldn't be considering any other option at all. So it looks like this newer design might be the better choice for me in this particular instance. I hope so, time will tell.

Joe


Re: New to the list

Rob Robinett
 

Ulli ON5KQ has suggested that moving the feed point of a LOG by a few feet can move the null direction and minimize RFI pickup.

On Thu, Jul 15, 2021 at 3:59 AM VE3VXO <ve3vxo@...> wrote:

Yes well, it may be a while but I will certainly do so.  This started out with me trying to use a phased pair of LoG antennas to improve reception of europeans on 160m to my tiny noisy suburban lot without towers and huge antennas.  KK5JY suggests a phased pair of LoG's can give a cardioid pattern with a broad backside null.  I am getting some deep nulling but in an unexpected direction and it doesn't appear that the pattern is what I had hoped and I'm guessing local conductive objects and maybe the TX antenna are destroying the patten of the pair.  Or maybe something else is messing with me like the fact that the antennas are sitting on a high K dielectric which means that the effective separation distance isn't the same as the physical separation??  So getting out in the clear might help clear this up (pun intended).  Hopefully I can plow through setting all this up before 160m season is upon us.  One thing I have wished for is that in setting up the search terms for the map one could specify the TX power level of the spotted stations which would help with making the map more representative of the antenna pattern.  There are a lot of factors along the path and at the TX end that can play havoc with what I am trying to do obviously but now that I see the power of these newer data analysis tools I think there may be something to the idea at least I should give it a try.

Thanks for your help and encouragement guys....Joe

---------- Original Message ----------
From: Rob Robinett <rob@...>
Date: July 14, 2021 at 11:06 PM

Joe,

Please report your results!

Rob



--
Rob Robinett
AI6VN
mobile: +1 650 218 8896

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