Here are a few questions that have/may come up, and some answers. They may not be good answers, but they are answers nonetheless.
"I've been using the Chrome browser for a while and there's suddenly no audio? What's the deal?
We have a web page just for this situation - read more by going to the "Fixing Chrome" page.
"What is that "= kHz" button in the tuning bar used for?"
In the "old days" with analog VFOs hams just plopped down
anywhere on HF "close" to the intended frequency - which made sense
since few dials were accurate to much better than 1 kHz. These days, where
nearly everyone has a digitally-synthesized transceiver that is actually both
stable and accurate in terms of frequency, most hams - at least in the
U.S. - seem to have taken to setting their frequency dial to
"something.00" kHz (or, occasionally, "something.50").
Why? It could be OCD, or it could just be that it's easier
to remember a "whole kHz" frequency that ends with zeros. Because
of this tendency I added the "= kHz" button to "snap" the tuning to the
nearest even kHz ("something.50" will round UP) because most
stations will be there, anyway - and it prevents you from needing to
click your mouse a bunch of times to dial it in. If you are using
SSB and tuning in a station that is at "something.50" kHz you can still
use "= kHz" - just hit the "- -" or "+ +" key and you will be stepped
down or up 0.5 kHz, which is still fewer steps than clicking the
button a bunch of times or directly typing in the frequency.
"If I zoom in tightly on the location of the Northern Utah WebSDR on the map on the bottom of the page at the WebSDR.org web site
I see that there are several different WebSDRs, each in a different
location on the map, very close to each other. What's the deal?"
This map uses the "grid square" information to show the
locations of the WebSDRs, but since the servers at the Northern Utah
WebSDR are all in the same place, only one of those markers would
appear - and which server, exactly, showed up on the map seemed to be
entirely random. To spread them out, only the "Yellow" WebSDR's
location is correct, with the other WebSDR(s) being one "sub-grid" off
from the main server. While zoomed out, you will still see only
one, but you will see all of them if you zoom in far enough..
"What are those light, horizontal bands that appear across whole waterfall?"
Those are most likely static crashes - and that's what distant
lightning, propagated on HF like other signals - looks like and because
it is a burst of white noise it covers a wide range of frequencies at
once. The "brightness" of the crash on the waterfall is indicative if its relative
signal strength where "white" means that it is pretty strong!
Because it can be a strong,
broadband signal not even fancy DSP can do a lot about it, but this
WebSDR has a noise blanker that helps to clip the level of this noise
and allow a faster AGC recovery than would otherwise occur.
Propagated lightning static tends to be worse on the lower bands
(160, 80/75, 40) and is notably weaker on the higher bands.
During the winter there are fewer thunderstorms across North
America and this is less common, but in the summer there are times where the bands are
constantly barraged with this type of noise.
often use a WebSDR when on a round table or net - but it's a pain to
mute the WebSDR when I transmit. Is there another way?"
The most obvious way to mute the receiver is with the "Mute"
button near the volume control on the WebSDR. If you click this,
it actually stops the audio at the WebSDR, reducing its processor load
and network bandwidth. While this is preferred as it saves
bandwidth, there are other ways to quickly mute the audio:
Many "multimedia" keyboards have a button on them - usually
along the top row - that, when pressed, will toggle the speaker audio on
and off. These buttons/keys often have a symbol that looks like a speaker with a diagonal line through it.
Some newer browsers (recent versions of Chrome and Firefox)
have, in their tab along the top of the screen, a very small speaker
icon when they are at a site that has embedded audio. You can
click on that speaker icon on the tab to mute the audio, at which point
the icon will switch to a speaker with a diagonal line through it - but remember that you muted it that way when you want to hear the audio again!
Muting using this tab may be more convenient since the speaker
icon can be visible even if you have hidden the window with the WebSDR.
On your computer/operating system it may be possible set up a shortcut or "hot" key to mute/un-mute the audio.
Turn down/off your computer speaker.
Rig some sort of relay keyed by your rig's PTT output that mutes your computer speaker(s). For a brief article describing one way in which this may be done, clickhere.
"People report that they hear an echo on my signal, even though I turn down my speaker. What's the deal?"
Of course, if you are transmitting and your computer is on the WebSDR and you can hear your own signal, some of the audio from your computer will make its way into your microphone - and it will
be heard, even if the volume is quite low: You should either mute
your audio completely, or wear headphones - although audio can "leak"
out of many headphones and still be heard because the microphone will
probably be near your head!
If you have connected your rig to your computer to run "sound
card" modes like FT-8, RTTY, SSTV, JT-9 or many others it may be that
your "speaker output" is always
getting to your radio. Some radios (possibly including the Elecraft K3) seem to pass some of this audio
through, even when one is not in a "digital" mode which means that if
you are listening to a WebSDR, your computer audio may be getting into your rig directly and then being transmitted.
The best way to avoid this - and to avoid other issues (such as transmitting email notifications, system sounds - or music) over the air is to use a separate sound card that is dedicated ONLY to
digital mods: This "other" sound card could be another device
plugged into your computer's internal expansion bus, or it could be a
USB device such as an
external sound card or a rig interface such as a SignaLink.
having computer system audio being sent to that "other" sound card you
won't get that echo or be embarrassed when your computer's audio gets
blasted across the 20 meter FT-8 subband. It happens all of the time to others - don't let it happen to you!
"What's the deal with 'high performance receivers'? Are there 'low performance' receivers?"
There are two classes of receivers on the Northern Utah WebSDR:
The "High Performance" receivers that are relatively
narrow-banded (96 or 192 kHz wide) that use high-performance sound cards and QSD (Quadrature Sampling Detector)
mixers that can handle both weak and strong signals at the same time as
they use the same sort of hardware found in high-performance HF rigs.
Those that are not "high performance" receiver use inexpensive
"RTL-SDR" dongles. The dongles are attractive in that they are
very cheap ($4-$80, depending on features - the ones we use are $20 each)
and can cover up to about 2 MHz of spectrum at once - but this comes at
a cost in performance: They have only 8 bit A/D converters which
means that if you adjust them to receive weak signals, strong signals
will badly overload them while adjusting for strong signals means that
it's likely that they won't hear weak ones. With proper filtering
and precise level adjustment one can get closer to a happy medium, but
their use is inevitably a trade-off. It's because they are so
cheap and relatively broadbanded that they are an attractive way to get
"some" coverage over large frequency ranges with generally-acceptable
performance. In several cases, even though we could cover 2 MHz of bandwidth, we only cover 1 MHz - as in the case of the
31M-30M and the 15M-13M bands. This was done because there wasn't
anything of particular interest immediately outside this 1 MHz
frequency range, the receivers work slightly better with reduced coverage and running them at "only" 1 MHz bandwidth reduces processor loading.
"What is that "buz-buz-buz-buz" that I keep hearing every few minutes?"
We have no idea - it may be some sort of ocean wave
or ionospheric profiler. It seems to be audible on some band
nearly everywhere in the world.
"Speaking of "buz-buz", what's the deal with the beehive in the logo?"
Utah is known as the "Beehive State", the idea being that the
beehive is a symbol of industry as used in the "highly productive and
busy" sense. A suspiciously similar-looking beehive - complete
with bees flying about - may be seen on the great seal of the state of
Somewhat amusingly, it is illegal in the state of Utah to
use a skep - that traditional-looking dome-shaped beehive. The
reason for this seems to be because these structures originally did not have
"movable frames to all the hive’s parts so that access to the
hive can be had without difficulty" and that harvesting honey from them
often required destruction of the hive and/or the need to kill many bees.
The antenna? Bees have not passed any HOA restrictions on
putting Yagis on their beehives as they are naturally equipped
with their own antennae and doing so would not be in their own
interest, so they are all set up for the HF bands! Maybe they are causing the "buz-buz-buz-buz"!
"What are those "sweeping things" that I see between 4.5 and 6.5 MHz (and maybe other places) - especially at night?"
We think that those are coastal wave profile radars used to
analyze the ocean swells. A Wikipedia article on these types of
systems - and links to more information - may be found here: https://en.wikipedia.org/wiki/Wave_radar
waterfall/words on the page take up only a small portion of my giant
monitor and/or it's all too small for my eyes and I want to make
everything bigger - how do I do this?"
Many browsers have a "magnify" feature that allows one to
"embiggen" a web page and everything on it. On most browsers this
is done by pressing and holding the "ctrl" and then hitting "+" (plus)
key. For this you can use the "+" key on your numerical keypad,
or you can use the "+" key that shares the "=" (equals)
key next to the backspace - but that one will require that you hit
"shift" as well to access the "+". To reduce the size, use the
"ctrl" and "-" (minus) keys in the same way, or, on many browsers, you can use "ctrl" and then "0" (the number zero)
to reset back to normal. Most modern browsers will associate this
setting to that particular web site and its pages and leave the other
web pages as they were.
"Why do I hear signals belonging to hams outside some of the ham bands? Are they actually transmitting there?"
This is a spurious (image)
response due to the way sound cards work. For example, at a
sampling rate of 192 kHz the highest frequency that can be accurately
represented is half this - 96 kHz at the Nyquist limit.
Frequencies above this will "wrap around" and move down, away
from 96 kHz. The sound cards contain low-pass filters that help
prevent this, but they aren't perfect "brick wall" which means that
they will respond increasingly weakly at the input frequency goes above
the Nyquist limit - but they aren't completely gone. To work
around this adjacent bands have a bit of overlap so that one can get
away from this response. Examples of this spurious response are
on 20 meters where a strong signal on, say, 14190 may also appear
around 14000 - 192 kHz below. In radios that use sound cards as
their input devices (e.g. most modern Elecraft transceivers)
this is avoided by only "looking" at signals that are well away from
the "edges" of the input bandwidth response where the Nyquist filter's
attenuation is stronger.
"Why are 160 and 630 meter meters covered on two separate receivers?"
You may have noticed that there is not only receiver marked as "160M", but another one marked "630M-AM-160M" that also
includes the 160 adn 630 meter band. When the Northern Utah WebSDR was
originally put online there wasn't enough equipment on-hand to cover
more than the bottom 96 kHz or so of the 160 meter band and the
remainder of the band had to be covered by the lower-performance "630M-AM-160M" receiver.
Since then, we've increased the coverage to include the bottom
192 kHz of the 160 meter band, so it's almost completely covered, but there was
no real reason to change the "630M-AM-160M" - which also includes the
120 meter "tropical" shortwave broadcasting band and 2.5 MHz WWV/H.
Anyway, Murphy's law says that if you really
need to listen to something on 160 meters, it will be in that top 8 kHz
or so that the "main" 160 meter band isn't covering. The
dedicated 630 meter receiver offers superior performance over the
incidental coverage on the "630M-AM-160M" receiver.
"What's the difference between '75' and '80' meters - isn't that the same band?"
Both "75" and "80" refer to the 3.5-4.0 MHz amateur band - and
the reference is somewhat hsitorical: Decades ago, only the upper
half (or so) of the band was available for phone operation (in the U.S.)
and if one does the math, the top end of the band - 4.0 MHz - comes out
at exactly 75 meters. The distinction was that "75 meters"
referred to the phone portion and "80 meters" referred to the CW
portion. More recently, phone operation for U.S. (Extra class) amateurs
has been extended to 3.6 MHz - a wavelength of 83 meters.
Although historical, the convention remains: "75" meters is
the top 1/3-12 of the band whereas the rest of the band is "80" meters.
On this WebSDR the designation of "75 PH" ( for 75 meter phone)
conveniently takes advantage of this nomencalture, referring to the top
portion of the band with "80 PH" being the middle portion and "80 CW"
being the bottom of the band - although this last segment also includes
the very bottom portion of the phone allocation.
sitting here listening and I hear a "twit" sound across the frequency as if
someone just tuned their transmitter's dial up the band quickly while keyed down. Who's doing that?"
These are ionosondes - a sort of chirp radar that
is used to analyze the composition of the ionosphere. These
sweeping transmitters - along with synchronized receivers - function as
radars that can determine the height and density of the ionosphere, and
with similar devices at other frequencies (you can find them all over the HF spectrum)the quality of the refractive properties and the MUF (Maximum Usable Frequency)
can be dynamically tracked. By sweeping the frequency, the delay
in the time that it takes the signal to go up and back down from the ionosphere means that the return
signal will be at a slightly different frequency than that of the transmitter
which will have moved frequency in that time, so the difference in
frequency between the transmitted frequency and the return is
indicative of the total path length.
Here are a few web sites that have information about/from those systems:
another station really close to the frequency on which I'm listening -
how do I filter it so that I can hear what's going on where I'm
If you own a radio made within the past 30 years you probably
have a "Passband Tuning" or "IF Shift" control that allows you to move
your filter back and forth. If you own a modern receiver you can
adjust the high and low sides of your filter independently to narrow
your bandwidth at the top or bottom end of the voice channel on which
you are listening to reduce that edge of the passband to remove some of
the adjacent-channel interference. On this WebSDR, there are
several ways to do this:
Select the "Narrow" version of the mode that you are using (e.g. LSB-nrw, USB-nrw).
Click on the "narrower" button to reduce your overall receive bandwidth bandwidth (there are actually two different buttons that do this...)
Under the "Passband Tuning" section use the "<<IF
Shift<<" or ">>IF Shift>>" buttons to "slide" your
passband up or down, away from the interfering signal.
Use the "<<Low PBT", ">>Low PBT" to slide the
low-frequency end of your receive passband down or up, depending on
which sideband you are using.
Use the "<<High PBT", ">>High PBT" to slide the high-frequency
end of your receive passband down or up, depending on which sideband
you are using.
On the screen, grab the low or high end "skirts" the passband with the mouse (e.g. hover the cursor over it then press-and-hold the left-mouse button while dragging it) to change the passband. It is recommended that you zoom in before doing this!
If you click any of the "USB" or the "LSB" buttons after
setting a custom bandwidth that it will reset them to the default
"There is a loud tone (carrier) on the frequency where I'm listening - What is that?"
Some of our amateur bands - notably 40 meters above 7200 kHz
and large chunks of the 80/75 meter bands are used for international
shortwave broadcasting in other parts of the world and shortwave being,
well, shortwave, we can often hear those signals - particularly at
night or early morning in North America. To a degree, you can remove this tone by
clicking the "autonotch" button near the volume control - but this will
remove only the carrier, not the modulation (speech, music.)At
other times you will hear short-duration carriers while people tune up
or, unfortunately, due to the occasional jamming. It is recommended
that you NOT
use this "Autonotch" feature when receiving CW signals as this will dutifully remove them!
"How do I engage a noise blanker or noise reduction on the WebSDR?"
It's no secret that noise reduction works best on periodic
noise such as the "buzz" of a powerline but works less-well on the
"white" noise of a quiet band where signals are simply weak and really
doesn't work at all when signals overlap. In an ideal situation,
a WebSDR uses a quiet receive site so that the majority of the noise
that it receives is "white" noise - so a noise reduction system would arguably be less effective.
Having said that, there is a noise blanker that is always active on this WebSDR (and not controllable by the user) to deal with the occasional power line noise that pops up: We're working with the power company to mitigate this.
about a noise reduction? At this time, there is no additional
noise reduction feature available on this WebSDR - mostly because
adding this would increase the processor loading and reduce the number
of simultaneous users/bands that could be supported. It is
possible to route the audio that you are receiving through a noise reduction program that is on your
computer: In short, one uses a program such as "Virtual Audio
Cable" to route the audio to a program like "MMDSP" and then to your
speaker - although a cable from the output of one sound card and into another sound card (on the same or different computer)
can work in a pinch. There are articles on the Internet on how to
do this - and it is admittedly awkward, but it does work.
"Can I use the WebSDR to receive digital modes like FT-8 or WSPR?"
Because of resource and complexity limitations, the WebSDR currently has no built-in decoder for these modes, but it is
possible for you to route the audio that you are getting from the
WebSDR into a program that does the decoding. As with the noise
reduction mentioned above, it would be necessary for you to somehow
"pipe" your receive audio into the decoding program - with with a
program like "Virtual Audio Cable" or with a hard cable.
issue is that because of the nature of the Internet and the way your
computer processes sound, there may be occasional drop-outs and/or
changes in the delay between when the signal hits the WebSDR's antenna
and it comes out of your computer: While this may be an annoyance
on modes like CW or PSK31 where characters can be missed, this change
in timing can completely mess up the reception of WSPR, JT-9 and FT-8
transmissions, either degrading them or completely wrecking their
Finally, remember that any mode that requires
tight clock synchronization (like WSPR, FT-8, JT-9, etc.) can also be affected if the overall delay across the network and in your computer is too great.
"Why don't you cover from 0-30 MHz all in one swath?"
This is a bit of a technical challenge to accomplish, requiring what is still exotic hardware (very fast A/D converter, a very fast processor platform such as a multi-core graphics card or dedicated hardware like an FPGA) and
without a "front end" using a GPU or FPGA this task is arguably beyond
the capability of almost any multi-core, multi-GHz computer that is
currently available. Such
hardware, while commercially available, is still quite expensive - as
in the thousands of dollars. Because of this, the support by the
WebSDR program is largely for acquisition methods that use relatively
inexpensive, consumer-grade, off-the-shelf hardware like sound cards or RTL-SDR dongles.
are less-expensive devices - such as the KiwiSDR that can
cover 0-30 MHz that FPGAs for their "heavy lifting" but these can
only support a handful of users at once.
Finally, any RF
acquisition system that "inhales" the entire band from 0-30 MHz all at
once - even if it uses a 16 bit A/D converter (most don't!) - can have significant
issues related to signal dynamics: If it is adjusted to "hear"
the weakest (sub-microvolt) signals,
it will likely overload on stronger signals elsewhere in the
RF spectrum. In the case of a "direct sampling" radio like the
Icom IC-7300 or IC-7610 they get around this by having filters
that lets only a
small "window" of spectrum through at once along with dynamic gain
control: Neither of these may be done if you have many users at
random frequencies scattered across the entire HF
"Why do I keep hearing WWV/H in several places on the "60-49M" receiver?"
This receiver uses an inexpensive "RTL-SDR" dongle which, with only 8 bits of A/D has rather limited dynamic range (in the 40-50dB range)making it prone to overload on very strong signals. The "WWV" problem, interestingly is not due to overload, but because there is too little RF
getting to the receiver input. For example, with just 8 bits
of A/D, one can have signals of +/- 127 or so - but during the daytime
when the band is quiet the A/D converter is only "tickling" A/D
readings of +/-2 to +/-4, which is equivalent of having an A/D
converter with only 2-3 bits!
The result of this is intermodulation distortion, which is why
WWV is appearing in several places. The only reason that it isn't
worse than it is is due to the fact that the post-A/D sample rate is
2048ksps so the effective A/D resolution is improved due to
oversampling and the presence of noise - but this can only go so far to
help the situation.
The work-around (aside from getting a "better" receiver)
would be to increase the antenna RF into the receiver a bit - but this
is a delicate task: Too much signal and the receiver overloads -
so the proper balance that will suit widely varying signal conditions is
difficult to find on a receiver with dynamic range issues.
Interestingly, it takes quite a bit A/D clipping (e.g. hitting full scale)
to have a significant effect on overall performance so it's a bit
better to put a little bit of excess signal into a receiver like this than it
is to put too little. Finding the best balance between
"underload" and "overload" takes a bit of ongoing work and
experimentation and continuing vigilance.
"Why does the 31-30M receiver work fine at times and not others?"
the "60-49M" receiver, this uses an RTL-SDR dongle - also with limited
range. At the time of installation the RF input level was adjusted on
a "best guess" basis - but we figured that experience would soon show
us if this setting was too high or too low. Clearly, there are times -
when the 31M shortwave broadcast band is filled with high-power
broadcast signals that the setting was "too high." In time we'll do
further analysis and tweaking - and if there is enough interest,
possibly implement a separate, high-performance receiver just for the
30 meter amateur band.
"What are those (faint) lines that I see on 160 and 80/75 meters during the day?"
During daylight hours the 160 and 80/75 meter bands can be
extremely quiet which means that very low-level signals can start to
appear. On these bands some lines - usually faint - often show up
and these are due to intermodulation products of AM broadcast stations.
This effect is likely due to nonlinear junctions that intercept
the energy, mix together and then re-radiate and this could be from
long runs of rusty and/or corroded metal such as runs of barbed-wire
fence (of which there is a lot near the antenna!) or imperfect connections on the antenna itself and/or its supporting structure.
At night these signals tend to disappear, probably due to a
combination of many of the AM broadcast stations that run 50kW during
the day lowering their power at night, but more likely due to the fact
that these bands get much noisier at night owing the reduction of
ionospheric absorption, the greater number of signals and the fact that
noise from all over can be more easily propagated to the receive
"Why are there several servers rather than all bands being on the same server?"
WebSDR software is designed to allow only up to 8 bands at once, so
additional bands must be hosted on another server. Using affordable
acquisition hardware (e.g. plug-in sound cards, various USB devices)
there are also definite, practical limiters on the number of these
devices that may be connected to the computer at once. Having
multiple servers also allows lower-performance (and less-expensive)
computer hardware to be used. As it turns out, we have access to
a large number of PC of modest computing power, so we are inclined to
"Where is 'Yooo-Tah' anyway?"
'dunno - it's somewhere west of Denver and northeast of Los Angeles. I
think that there's a big lake, a lot of seagulls, and some strange people that live
there that make it hard to find beer. Oh, there are mountains, too...
"How about more bands. I want more bands!"
The first priority was to support the "lower" bands such
and 40 meters as they are the most popular and useful on a WebSDR
system. In these days of lower sunspot activity the higher
bands (20, 17, 15, 12, 10 meters)
are hit and miss - particularly toward the 10 meter end of the spectrum - and as such,
the "lower" of these higher-frequency bands are being added first,
based on time, resources, and, to a lesser degree, the likelihood of
being open. As noted below, this system is entirely supported by
volunteers so there is a limit on time and expense that may be borne.
"Some WebSDRs have a 'chat' function, but not this WebSDR - why is that?"
Past experience by other WebSDR operators have shown that while
the "chat" function can be well used, but a small number of people
tend to use it as a platform for abuse: Such is the nature of the
Internet... (Have you actually met people, and are you really suprised about this??? Really???)
"I read about this site in Utah - you are using the large, steerable antenna there, right?"
There are two antennas on this site: A large log-periodic
beam antenna and a larger, omnidirectional wire antenna on a taller
tower that is not as easily seen, either from the highway or via Google
Earth - and we are using the wire antenna. The log-periodic beam
is not being used: It is pointed due East and it is not
steerable, and it never was. Owing to issues with this antenna
and its tower, there are no current plans to use this antenna with the
WebSDR - but who knows what will happen in the future?
"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.
At some point in the near future we'll provide a mechanism for
donations, but we're still working on the best way to do
that. If you have any questions/comments about this you may find
contact information on the "About" page.
For general information about this WebSDR system - including contact info - go to the
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