KiwiSDR FAQ - Northern Utah WebSDR

The KiwiSDRs at the Northern Utah WebSDR
Frequently-asked questions

Important:
If you are doing general listening on the HF amateur bands, please use the normal WebSDR receivers instead of the KiwiSDRs: The normal WebSDRs' receivers are generally better, anyway!

Looking for information on WSPR reports from the Northern Utah WebSDR? Click here.

If you plan to use the KiwiSDR - or other KiwiSDRs around the world - please review the KiwiSDR FAQ (link) for more general information.

Supporting the Northern Utah WebSDR:

"I've found the entire Northern Utah SDR system to be very useful for my HF operating - how can I support it?"

You can find out how to donate $$$ to help keep this WebSDR system online by going here : Any amount is appreciated - large or small. While we have some ads on the page, these provide enough to pay the power bill - but not much more, so we need to come up with extra $$$ to fully cover things like rent and maintaining the equipment or getting additional gear for upgrades.

"Hey dude - what's with the ads?"

There are recurring expenses such as site rental and electricity to name but two reasons for doing so. You can read more about the rationale for doing this here.

"Why are you doing this, and who is paying the bills?"

The reasons for having WebSDR systems are stated on the "About" page. In short, to provide a service to the amateur radio community and anyone else who is interested in the HF spectrum.
At the present time, the cost of the equipment and ongoing expense is being borne by a small number of individuals who have donated time, money and materials to get the system off the ground. Going forward, recurring expenses such as electrical power (we are the only users at this site!) and additional needed for maintenance and upgrades will continue.
We now have a way to donate $$$ to help keep this WebSDR system online by going here : Any amount is appreciated - large or small.
We also have what we hope are minimally-intrusive ads that we hope will cover at least some of recurring the expenses - For more info, please see the "Why Ads" article.

Why the KiwiSDR?

"Why do you have KiwiSDRs in addition to the WebSDR?"

Unlike the WebSDR, the KiwiSDR is capable of tuning continuously from (nearly) DC to 30 MHz, covering all HF amateur bands, shortwave broadcast bands and those in between.

"If the KiwiSDR is 'better', I should be using it instead of the 'normal' WebSDRs, right?"

Actually, even though they are using exactly the same antenna(s) as the normal WebSDR system, their performance is inferior to most of the individual amateur band receivers on the WebSDR system. This is because the "narrowband", "high performance" WebSDR receivers use high-quality 16-bit A/D converters and narrow-band RF filters on their front-end which improves their effective sensitivity and makes them far more resistant to overload and noise degradation in the face of other strong signals on the band and lightning crashes.
The KiwiSDR uses "only" a 14 bit A/D converter - and that "sees" the entire HF spectrum which means that strong signals in, say, the 31 meter shortwave band can cause subtle degradation everywhere else. What's worse than that is lightning static that often appears from across the country on the lower bands (e.g. 160, 80, 40 meters) that can simply overload the A/D converter, causing that same "crash" to appear all across the HF spectrum - even though it really doesn't do that!

"Which is better for ham radio usage - the KiwiSDR or the normal WebSDR?"

For the reasons noted above, the KiwiSDR is better for things like round-tables on most amateur bands: It can be slightly more sensitive, more resistant to nearby signals, and more resistant to out-of-band static crashes. In the opinion of many, the WebSDR just sounds slightly "better".
The KiwiSDR can, at most, handle 8 users - and some of those user "slots" are permanently occupied by WSPR decoders tuned to various bands as can be seen by clicking on the "Users" tab. In contrast, the WebSDR systems can handle well north of 60 users at once.
The audio delay on the normal WebSDR is only a fraction of a second while the audio delay on the KiwiSDR is around 1 second, making it harder to participate in round-tables!
Note: If we see too many people "sitting" on the KiwiSDR when they normal WebSDR would be better, we will consider taking action to prevent this - so please don't do it!

Operating the KiwiSDR and various issues:

"The KiwiSDR just kicked me off - why?"

To prevent "squatting" or other abuse, there is a maximum 30 minute time limit per session of the KiwiSDR and a maximum of 90 minutes per user during each 24 hour period.

"How the hell do you tune this thing?"

The easiest way to tune the receiver is to select the mode first (e.g. USB, LSB, AM) and then enter the frequency in kHz (including decimal places) in the bar in the upper-left corner of the pop-up on the right edge of the screen.
You can also click on the waterfall display, the frequency bar, or in the white (blank) area just above it - but note that the frequency to which it will tune will be in the center of the receive passband as defined by the yellow brackets.
On some frequencies above the frequency bar you will see labels: Clicking on those will tune the receiver to the frequency and mode defined by that label. (Users cannot change these labels.)

Somewhat annoyingly, after you click to tune, your mouse cursor may drag the frequency around. Click ONCE to change the cursor back to normal to stop this.

If you click and hold the left mouse button on the waterfall, frequency bar or the area above with the labels, you can drag the waterfall back and forth on the screen.

"I somehow dragged the yellow passband brackets around and now my (USB/LSB/AM) mode doesn't work right. How do I 'fix' that?"

If you have somehow changed the passband setting for a mode, it will remain "changed" during your current session. Because this is so easy to do by accident, there's a simple way to fix it:

Hold the SHIFT key down while Right-Clicking on the waterfall or frequency bar. In the options that show up you will see "restore passband" and click on that to "fix" your mode filtering.

On some browsers you'll get a dialog box from the browser itself. I'm not quite sure how to dismiss this without also making the dialog box go away other than selecting something like "copy".
To make the box (from the KiwiSDR) go away (that is, if you don't want to pick anything) hit the ESCape key or left-click once somewhere on the waterfall display.

"I used to see a waterfall for the whole HF spectrum, but I don't see it now. What's the deal?"

It takes a lot of powerful hardware to "inhale" all of the HF spectrum at once and process it: Were it done only with a computer, the fastest PC around may not even be able to do it unless it also used a fancy graphics card's GPU cores as well! The "other" way to do this is to use FPGAs (which are versatile programmable logic devices) in which one can "program" specialized hardware that is very good at this task - and the KiwiSDR has one of those. Because its resources are limited, in addition to being able to receive signals, this FPGA also has to function as a GPS receiver and it is what produces the data for the waterfall display.

"Are there several KiwiSDRs?"

Yes, there are three KiwiSDRs on site - the "main" one being found at kiwisdr1.utahsdr.org. If you connect to KiwiSDR1 and it is "full", you will automatically be forwarded to another Kiwi with available receiver slots - if they are available..
There are other public KiwiSDR system across the world: Go to the sdr.hu site for more information.

"Who is user 'NorthernUtahWebSDR_KiwiWSPR' and why is it hogging the user slots?"

There is another computer on site ("websdr3" - the blue one, actually) that is making audio-only connections to the KiwiSDR so that WSPR transmissions on the frequencies you see associated with that user may be decoded. By using this method, there is lower processor loading on theKiwiSDR itself doesn't do the processor-intensive WSPR decodes and the "other" decoder does a better job with weaker signals. Because the other computer is local, it doesn't require any Internet bandwidth.
Because it is an audio-only slot, it doesn't "hog" any of the "full-bandwidth" waterfall slots.

"I could swear that I connected to 'kiwiwspr1.utahsdr.org' but I ended up on "kiwiwspr2" instead - why's that?"

When at maximum user capacity the KiwiSDRs have the ability to redirect the user's computer elsewhere - and in this case, when KiwiWSPR1 is full, it will automatically direct users to KiwiSDR2 which will likely have a "free" slot.
Because these KiwiSDRs are operated in "8 channel" mode, only the first 2 channels will have a full-spectrum waterfall display available to them. For this reason 6 of the channels on KiwiSDR1 are occupied with the "audio only" slots (mentioned above) which will cause the 3rd user to end up on KiwiSDR2 where he/she will get a full-spectrum waterfall.

Remember: If you are listening to amateur-band frequencies, Please use the "normal" WebSDRs, instead as they can handle many dozen simultaneous users!

Features of the KiwiSDR:

"I hear that the KiwiSDR has some fancy features. What can you tell me about them?"

The KiwiSDR has a number of additional features that are available under the "Extension" drop-down tab. Very briefly, these include:

cw_decoder - A built-in Morse decoder. This is a relatively new addition and is likely to be greatly improved as time goes on. The key to making this work is to zoom in on the signal to be decoded and dragging the bandpass filter's edges to make the filter as narrow as possible. This extension also includes a "threshold" graph and the received tones should be near the top. The "cleaner" (e.g. less noisy) the signal, the more space there will be between the CW tone at the top and the noise (random dots) lower down in the graph. The threshold value should be set such that it's "comfortably below" the CW notes at the top - but this threshold gets narrow and narrow the noisy the signal gets and also the wider the bandpass filter is. Read the KiwiFAQ for more information.
devl - A "development" tab that may or may not have any options. (They usually do not...)
fax - This can be used to receive and display HF FAX transmissions in the browser. Within the tabs are lists of stations that may or may not be transmitting and you may or may not even have propagation to those stations. The map will slowly appear on the screen when properly tuned in.

There will probably be a black bar somewhere in the picture with the contents on either side. To manually synchronize the FAX transmission place your mouse's cursor in the middle of that black bar and while holding the SHIFT key, click the left mouse button.
You will have to re-synchronize when you tune to another station - and probably when the FAX transmissions from a given station stop and resume.
Read the KiwiFAQ for more information.

fsk - This is the same as RTTY, or RadioTeletype. The various settings allow both Baudot and ASCII to be decoded but the precise configuration for these modes is beyond the scope of this document. Read the KiwiFAQ for more information.
ibp scan - On certain frequencies in the upper HF bands are CW beacons located across the world that transmit on a particular schedule, enabling one to quickly determine if the band is open: This extension facilitates monitoring of these beacons. Read the KiwiFAQ for more information.
integrate - This sets up a second audio-only waterfall that allows one to integrate over time, potentially allowing persistent weak signals to be made more visible. Read the KiwiFAQ for more information.
iq display - Almost every SDR uses "I" and "Q" signals to recover the signals and in this mode, the amplitude of those signals are displayed on a phasor scope with the "I" in one axis and "Q" in the other. If you tune in an AM signal zero beat you can see this "spin" depending on the frequency error. The box that pops up has various filtering and phase-locking options. Read the KiwiFAQ for more information.
lms filter - The KiwiSDR has some noise reduction and notch filter capabilities that are still a work in progress available under the "Audio" tab in the right-hand window. This selection brings up some "knobs and buttons" that directly affect how well these filters do/don't work. Read the KiwiFAQ for more information.
loran c - In some parts of the world (Russia, parts of Europe and Asia, east coast of the U.S.) there are Loran C stations still in operation - or undergoing testing with new technology that may result in the system being rebuilt as an "un-jammable" augment to GPS. This extension allows analysis of the signals from these stations. Read the KiwiFAQ for more information.
navtex - This is an information service used to pass along traffic to ships at sea. Because of its naval use and the low frequencies involved, you may not ever "hear" anything unless you have an antenna that works well at these frequencies and you live near-ish a coastline. Read the KiwiFAQ for more information.
S_Meter - This provides a graphical analysis of the S-meter readings. This may be used to track the fading of the station to which you are tuned or, if they are "local", it may help facilitate that other station's antenna testing. Read the KiwiFAQ for more information.
TDoA - This allows coordination with other KiwiSDRs to help determine the geographical location of signals being received. At the present time, it takes a 30 second snapshot of the signal in question and uses this, along with a digital recording pulled from other selected stations (at least 3 are needed for an unambiguous fix) that can also hear this same station to calculate the likely location (to within a few 10s of miles/km at best): This means that if you have any hope of determining a station's location, it must be audible to all other stations that you have selected, the transmission must be more or less continuous over the 30 second period and that it must be the only station that was transmitting at this time. DO NOT expect decent or consistent results from this system until you get practice and have a better understanding of how it works. In addition to the HELP button on this screen, please read the KiwiFAQ for more information. Nils, DK8OK has written about how to use the TDOA extension in a .PDF that may be found HERE - be sure to check it out if you use the TDOA.
WSPR - Before you use a KiwiSDR for WSPR reception, please read the information at the Northern Utah WSPRNET page. This brings up a window where one can select a band on which you can park a WSPR decoder to decode any signals that might be there with the results posted to wsprnet.org. Because WSPR reception/processing is handled via an external machine (see below), WSPR reception/reporting via these KiwiSDRs should not be used. While WSPR logging/reporting is done at the Northern Utah WebSDR, we are not using the built-in WSPR decoder to do it. Read the KiwiFAQ for more information about using the WSPR decoder built into the KiwiSDR.

"In the stats I see reference to a GPS receiver. What's that for?"

Because the KiwiSDR uses a fairly powerful FPGA, it was easy to add an inexpensive GPS "front end" chip and implement "simulated" GPS receiver hardware/software on the FPGA. This allows the KiwiSDR to not only determine its precise location, but it also allows it to precisely set its "dial" frequency and have an accurate time-of day clock.
It is this accurate clock that allows the KiwiSDR to participate with others in the TDoA ("direction finding") function by precisely time-stamping the sound recordings that are processed - along with those of other receivers - to determine the signals' likely locations.
The GPS clock is also used for WSPR reception which requires a precise clock along with frequency stability and accuracy.
The results of the GPS receiver's operation (location, timing, etc) are not available to the casual user.

Yet again:

The KiwiSDRs have many more features than can possibly be covered here - please read the Quick start guide (link) and follow some of the links within for more information than you probably want.

For more detailed information about the Kiwi's TDOA (direction finding") extension, check out the .PDF on DK8OK's blog page.

For more general questions about HF and the things you will hear, go to the WebSDR FAQ page.

Additional information:

For general information about this WebSDR system - including contact info - go to the about page.

For the latest news about this system and current issues, visit the latest news page.

For technical information about this system, go to the technical info page .

For more information about the WebSDR project in general - including information about other WebSDR servers worldwide and additional technical information - go to http://www.websdr.org

Back to the Northern Utah WebSDR