Northern Utah WebSDR server
Latest News and current issues
Recent events and resolved issues:
19 April, 2018. Comments:
The "630M-AM-120M" band has been shifted up slightly, now
covering only down to about 519 kHz. This was done because there
is now a dedicated 630 meter band receiver.
The "60M-49M" band has been shifted up, now starting at about
4700 kHz and covering to just above 6700 kHz. This was done
because there are (probably)
more signals of interest 6600-6700 kHz range than there were down
around 4500 kHz - although I don't know offhand what those would be...
We have enabled ads on the WebSDRs - trying to keep them as
unobtrusive as possible - to help offset the "fixed" expenses related
to operating a WebSDR, such as power and site rental. One
side-effect is that in some cases, they slightly delay the loading of
the web page. To read more about why we did this, go the "Why ads?" article.
17 April, 2018. Comments:
Bands on individual servers are now in order of lowest to
highest frequency rather than by "high performance" receivers first and
then increasing frequency.
The S-meter/waterfall gain settings on 40 meters that had been
adjusted to compensate for the effects of the high-pass filter have
been restored to their original values.
A/D converter gain values on the 630 meter receive system were adjusted to provide better overall signal range.
Minor name changes of several bands for better consistency.
15 April, 2018. Comments:
Resolved issue: The high-pass filter was rebuilt. This is used to block low-frequency (<25 kHz)
energy picked up by the antenna in the form of electrostatic coupling
that was causing problems at low receive frequencies - being
particularly noticeable on the AM broadcast band as mains-induced hum.
The original filter was found to have a broad, shallow "notch" at
around 40 meters that had reduced signals by about an S-unit.
Resolved issue: One of the sources of an intermittent problem where intermodulation distortion from
AM broadcast would appear and disappear is believed to have been
solved. This was probably due to a flaky solder connection in the
"wideband" branch of the signal path where one or more of the notch
filters used to reduce the signal level from strong, local stations
would occasionally fail.
Upgrade - 15 Meters: The
15 meter amateur and the 13 meter shortwave broadcast bands
have been added to the "Green" server. This uses a relatively
low-performance RTL-SDR dongle preceded with a custom-built,
tightly-filtered frequency converter, but it was verified that just
will hear the ionospheric noise floor when the band is closed.
Upgrade - 2 meters: A south-pointing, 5-element 2 Meter Yagi is now being used for 2 meter
reception. This Yagi points toward the Salt Lake City metro area where
there is the greatest concentration of repeaters.
Upgrade: The "Blue" server has been added, providing a few additional bands.
Change: 2 meter coverage has been moved to the new "Blue" server.
Upgrade - 6 Meters: The bottom 1 MHz of 6 meters has been added, covered on the
"Blue" server in preparation for the upcoming sporadic-E season.
The antenna for this band is not yet properly mounted so it does
not (yet) work very well.
Upgrade - 630 Meters. The
630 Meter amateur band has been added to the "Blue" server.
This receiver covers from about 389 to 484 kHz, allowing some NDB
(Non-Directional Beacons) to be heard - particularly at night.
Like 160 meters, the 630 meter band is mostly a "winter" band
owing to the crescendo of static that accompanies the summer season.
While this band is also covered on the "630M-AM-160M" band on the
"Yellow" server, this receiver has much better performance. Note
that this band can, at times, be badly affected by the intermittent
powerline noise and intermod/antenna issues that we are experiencing.
11 April, 2018.Notice: There are/will be some occasional outages over the next week or so as our ISP does some equipment upgrades.
Power Line noise:
There is an intermittent power
line related noise that occasionally shows up - and we are working to
resolve this issue - but the system's noise blanker seems to be able to
remove most of it. This noise is typically the worst on 80/75
meters, but it seems to disappear at night as the band opens up and the
ionospheric noise submerges it.
Audio/system drop-outs: There have occasionally been periods where the audio will drop
and/or the waterfall will freeze briefly. This is due to
occasional network drop-outs/queuing and may have several causes - some
of which have already been addressed. This issue is being
analyzed and worked as it appears, but most of them are likely to be due to your network and/or computer getting busy for brief periods - see "Miscellaneous Quirks", below for some causes and work-arounds.
A "pop" in the audio and an accompanying change in signal level: There appears to be an intermittent cross-connection on the
antenna between a feed and guy wire that can cause noise in the received signals and levels to
fluctuate during very windy periods on site - particularly on the
lower (160, 80/75 and the 630M-AM-160M) bands. A similar-sounding - but unrelated - issue (described below) exists with the AM demodulator. Occasionally, this seems to be accompanied by an increase in
intermodulation distortion from AM broadcast band signals - a problem
that can affect the 75 Meter and lower-frequency bands.
Occasional shifts in baseline RF signal levels:
It was noted that signal levels would occasionally shift by
6-10dB across the board. It is suspected that there is an
intermittent connection in an RF jumper cable: A brief site visit
was made where connections were shaken and after several brief
drop-outs, the signal levels remained solid. The various
connectors/jumpers involved will be closely inspected during the next
site visit. This problem is related to that mentioned above and can be observed during windy periods.
There is an "image" problem on the "20CW" receiver:
Images about the center frequency on this receiver are not as
strongly attenuated as they should be which means that an "I/Q
Calibration session" is on the to-do list for the next site visit.
Occasional outages: We are working to
"neaten up" the installation so we occasionally have to take something
off line to dress a cable, replace a connector, "permanentize" an
installation. Tasks like this will cause outages of several
minutes duration. Some work is also being done at one or more of
the interim sites that provide the Internet connection that
occasionally result in outages.
Miscellaneous quirks (e.g. "It's supposed to be that way!"):
If the WebSDR is not on an active window on YOUR computer: If the WebSDR is not the currently active
window on your desktop, the computer will give it lower priority and
this will make audio drop-outs/waterfall freezes more common. The
same thing can happen if your computer is "busy" doing something else,
such as other programs, updates, incoming emails, etc. The same is likely true
with other platforms (phone, Mac, etc.)The first thing that you should do if you experience drop-outs is to switch to the window running the WebSDR. Don't forget that your own
Internet connection/ISP can result in drop-out issues as well. It
has been observed that on a typical Windows machine, if the processor
utilization is over 65-70%, you may experience occasional drop-outs due
to delays in the operating system providing processor time to the code
that produces the audio and draws the waterfall.
Waterfall not updating when you switch to another window: When the waterfall is not visible (that is, you have switched to a window and moved the one with the WebSDR in the background)
it will stop - which makes sense if you can't see it. What this
means is that when you switch back to where the waterfall is again
visible there will often be a clear line of demarcation between what
the signals were when you switched away and when you switched back.
Occasional burst of noise across the band correlated with strong signals:
This is sometimes the result of the noise blanker that is active
on all bands being triggered by the peaks of the strongest signal(s) on
the band. This effect is most easily spotted on 40 meters during
the daytime where there is one signal that is extremely strong - often
on the leading edge at the beginning of a transmission - and the band
is otherwise quiet. This effect should not be confused with other
things that cause similar-looking artifacts, such as static crashes
from distant lighting storms or brief signals from ionospheric and
ocean wave profilers.
When listening to AM, a sudden "pop" in the audio: It's not actually supposed to do this, but there a "quirk" (bug?)
in the AM demodulator that can cause this to happen, occasionally.
It seems to happen mainly when the signal level changes very
quickly due to QSB (fading)
but is less likely to happen on very steady signals or those with only
very slow QSB. The only "fix" for this - if it becomes annoying -
is to listen on USB or LSB and zero-beat the carrier.
The bands on the "other" server aren't visible to me unless I go to that "other" server: It is this way because there are two independent WebSDR servers.
If you notice some issues that are unrelated to those listed abovefeel free to use the contact info on the About
page to let us know about it. "Less-recent" events and resolved issues:
7 April, 2018. There
was an extended power
failure in the general area of the
WebSDR, caused by a pole fire, that resulted in an outage that
lasted significantly longer than a UPS powering one of the microwave
hops providing Internet connectivity could. Whether or not this
had anything to do with our intermittent
power line noise remains to be seen. This outage provided the
opportunity to reconfigure the power system to mitigate the
aforementioned power issues at the "next" site along the network.
5 April, 2018. Comments:
Upgrade: The original wireless link antenna used to provide connectivity to the WebSDR site was upgraded from its original 12" (25cm) to a 24" (50cm)
antenna, providing better link margin. This resulted in a pair of
outages that totaled 10-15 minutes in the morning between 1130 and
Upgrade: There is a UPS/power supply issue at the "next" site along
the network from the WebSDR and brief power bumps at this site will
cause a 3-5 minute outage. This will be fixed (which will, itself cause a 3-5 minute outage) in the next several weeks.
While on site today it was observed that the known-marginal north deadman on the other antenna tower (a log-periodic beam)
had pulled completely out of the ground, leaving the guy completely
slack. The already-in-process plan to replace these deadmen has
been delayed due to equipment problems of the person we have engaged to
repair this; In the meantime, the north guy wire has been (temporarily!)
attached to a large truck. There is no visible evidence of
antenna/tower damage. All three deadmen will be replaced, but
because the strongest winds are out of the north, this is the one that
is the most critical.
Under investigation: There is an intermittent issue where there are spurious 160 and
80/75 meter signals - most notably on 1940, 3480, 3600, 3750, 3870,
3920 and 3960 kHz, many of these seeming to involve a mix between 1160
kHz and other stations. For the most part these spurious signals
disappear at night when some sources of the signals reduce power as
well as the ionospheric noise on these bands increase. The
source of this problem is believed to be a problem with one of the
filter elements designed to reduce the levels of the AM broadcast band
signals. When this is at its worst the "630M-AM-160M" receiver may be unusable due to overload.
Resolved issue: It was discovered that, somehow, the sound card used for the
"10M BCN" had reconfigured itself, switching the receiver audio away
from the active input. This was fixed for good - I hope!
27 March, 2018. Comments:
Resolved issue: It was discovered that the "10M BCN" receiver intended to cover (most of)
the 10 meter "beacon" subband from 28.200-28.300 MHz was actually
centered on 28.350. This receiver was retuned to a center frequency of
28.245 MHz (this frequency chosen to include the NCXDF beacons at 28.200 MHz) and immediately several beacons - including the "K7EMX" beacon located about 70 miles (112km) in Salt Lake and another beacon in Texas (K5AB at 28.280 MHz) - were heard, indicating that the receiver is now working properly.
Resolved issue: It
was noticed that the "= kHz" button doesn't work correctly when the CW
mode is active. The problem had to do with the fact that unlike
other mode where the indicated frequency is that of the carrier (or suppressed carrier on SSB) the indicated frequency when using a CW mode is that of the center of the passband
- or 750 Hz. Because of this offset, the "= kHz" button caused the
frequency to jump, being rounded using that 750 Hz offset: After this
offset was taken into account in the code, this problem was fixed.
24 March, 2018. Comments:
Resolved issue: A
brief site visit by Mike for the installation of a high-pass
module on the main antenna feed which got rid of the AC mains related
"hum" on signals received on the AM broadcast band receiver. This
problem is believed to be related to the pick-up of AM mains
electrostatic fields from the antenna causing modulation of the
magnetic properties of an input RF transformer and/or the modulation of
one of the signal amplifiers. This module provides a
DC path-to-ground for the antenna as well as two (moderate) levels of lightning protection via gas discharge tubes.
It was noticed that a stray resonance in the added filter seems
to have caused approximately 1 S-unit of reduction in signals on 40
meters - but there is little or no actual loss of system sensitivity
owing designed-in signal margins. The filter will be modified
during the next site visit.
Resolved issue: Extra gain was added in the "10M BCN"
receiver's signal path. Although there are two low-power 10 meter
beacons known to be active in the Salt Lake area, neither one can be heard on this
receiver - but this is not unexpected as propagation would be only via
groundwave (which is rather poor on 10 meters, anyway) and the distance is simply too great to hear them.
21 March, 2018. Comments:
Under investigation: It was noted that the RF levels on all HF bands were shifting
randomly over the day by as much as 12 dB. A brief site visit was
made by Mike who lives near the site and he shook the cables/connectors
between the RF rack and the antenna - we may
have found an intermittent RF connection on a jumper cable: This
will be investigated further on the next "full" site visit.
The 10M BCN band was added at the time of this visit. We had an extra "Softrock Ensbemble II" receiver on-hand (it had been the "75PH" receiver prior to the recent upgrade)
which was reconfigured, putting it approximately in the middle of the
10 meter beacon subband. All that was available was the 96 ksps
sound card on the servers' motherboard - and this receiver lacks a
stage of RF amplification so it is going to be somewhat deaf, but it
should hear 10 meter beacons during even moderate band openings.
19 March, 2018. Comments:
Resolved issue: There was a "hummy" spur that drifts about on the 40PH band. The cause of this was unknown - and the symptoms were a bit perplexing: It was not super strong (only about "S-9") and weirdly, its image (equidistant from the 7221kHz center frequency) was only 6-10dB weaker. If this spur were on-frequency I would have expected that would have been much
stronger than it was and also that the image would be 40+dB weaker.
The implication of this was that this spur is probably far
off-frequency and what we were seeing was a rather weak spurious response
from that (very-strong!)off-frequency
signal. The signal path contains a large number of
filter elements and there are several post-filter RF amplifiers
and it is likely that one of these had "broken into song": The
amplifier design that is used should
have been unconditionally stable, but all bets are off when Murphy is
involved! The "fix" was to add some 2dB resitive attenuators to the outputs of these signal amplifiers.
Upgrade: The opportunity was also taken to add an amplifier stage to the
recently-added 17 meter receiver, allowing it to hear the background
Under investigation: The TCI 530 antenna was given the "shake test" and it was
verified that there is, in fact, some sort of intermittent connection.
There is strong evidance that one of the active antenna elements is close
enough to touch a guy wire when the antenna is vibrating due
Experimentally, 2-meter coverage was added to the system. At this time the antenna is not very good, so effective system sensitivity is quite poor. This site is approx. 70 miles (112km)
north of Salt Lake City so the signals from the repeaters in the metro
area are a bit weak with the current configuration. We are will
be making some improvements to the antenna system which may make it
more useful, but whether or not 2 meter coverage will be a permanent
part of this system remains to be seen.
18 March, 2018. Significant system upgrades/modifications:
Upgraded power: A
UPS with a built-in ferroresonant transformer was added to clean up the
power and provide continued operation in the event of brief outages.
Upgrade - 160M: Levels were readjusted and this receiver retuned and moved to a 192 ksps card to cover nearly 96% of the 160 meter band.
Upgrade - 80CW-80PH-75PH: A "triple" receive module was constructed that cumulatively provides complete coverage of the 80/75 meter bands.
Addition - 80CW: The the aforementioned module, this band was added, completing coverage of the entire 80/75 meter amateur band.
Resolved issue - 75PH: The sound card was modified (the "Aux" input was made available on the rear panel of the Asus Xonar DX)
to allow gain adjustment and the audio levels were properly set to fix the
problem where the sensitivity at the extreme edges of the band was
reduced by 10-15dB.
Upgrade - 40CW:
This band was moved to a 192ksps card and the center frequency
re-tuned, now providing coverage to the entire 40 meter amateur band.
Tweak - 60-49M: Levels adjusted, improving weak-signal performance - particularly during the daytime.
Upgrade - WebSDR Server #2 (Green) was added, providing:
dual high-performance 20-meter receiver module which, with a pair of
192ksps sound cards provides full coverage of 20 meters.
The change to higher-performance, narrow-band receivers resulted
in the loss of the (incidental) reception of the 22 meter shortwave broadcast band.
17M: The 96 ksps sound card that had previously been used for 40CW was installed in this server. Redeploying the original 80PH
receiver allows nearly 96% coverage of the 17 meter band. At the
time of installation it was noted that this receiver was slightly deaf,
so an amplifier will be added to its signal path during the next site
30-31M: Coverage of the 31 Meter shortwave broadcast and the 30 Meter amateur bands was added using a (low performance) RTL-SDR Dongle.
12 March, 2018.
There are some ongoing upgrades to the network infrastructure
that provides connectivity to the WebSDR. Because of this work,
there will be occasional network outages - typically of 4-10 minutes
4 March, 2018. A
modification was made to the code to "brighten" the waterfalls,
particularly during the times of day when the bands were "dead".
At about this time additional "Passband Tuning"
controls were added as well.
28 February, 2018.
This webSDR was moved to its designated site - an old HF research
site near the town of Corinne, Utah, about 70 miles (94km)
Salt Lake City. The antenna at this site is a TCI-530, an
omnidirectional Log-Periodic antenna - the same model as that used at the KFS
Web Site at Half-Moon Bay, CA. Now that we have the initial
we will work to improve the overall receiver performance, add more
bands and do more performance tweaks. While the person in charge
of the data networks lives fairly close to the site, the one in charge
of the RF infrastructure lives about 70 miles (and a 75 minute drive)away - a fact that can sometimes complicate dealing with the latter types of problems.
The system was down for several hours while some of the
critical components were "racked up" - that is, removed from their
temporary location (scattered
across a workbench)
and mounted/wired on shelves in an equipment rack. This
is not yet complete and a few more brief outages will occur in the next
several days while things are "permanentized."
The tentative date for installation of this system at its
"permanent" site is
28 February, 2018. When this happens, this system will be
for several hours as it is relocated and installed with subsequent
debugging of the computer, RF subsystems and the network. The IP address will change at
but there will be another server at the address of the old one that
will inform those users who land there, giving the new address and
prompting them to update their bookmarks. This "informational" server will be
online for a few weeks before being turned off.
The hard drives on the system started throwing errors were replaced with Solid State
drives, necessitating a complete rebuild of the operating system.
This process took some time and the system was unavailable
during for about a day.
7 Feburary, 2018:
The 40 meter receive system was reconfigured: A
custom-built dual 40 meter receiver module was used to replace the two
"Softrock Ensemble II" units that, together, had covered 40 meters.
The Softrock Ensemble II units were then reconfigured to provide
coverage of the bottom 96 kHz of the 160 meter band and chunk of the
"80 meter" phone band.
2018: This WebSDR server was first made public from a testing location
near Salt Lake City, Utah,
U.S.A. and was used to test software/hardware
configurations prior to the
installation at a quiet receiver site in Northern Utah. This location was somewhat "RF
noisy" with the amount of noise varying
wildly at times, so it didn't hear particularly
well - but it still did better than many home installations.
For general information about this WebSDR system - including contact info - go to the